Information project for oil and gas industry workers and students of oil and gas educational institutions. How to read dynamometer charts Shn consists of
General information
The most common method of oil production is the use of sucker rod pumping units (Fig. 1). The flow rate of wells equipped with SRP ranges from several hundred kilograms to several tens of tons. Pumps are lowered to a depth of several hundred meters to 2000 meters (in some cases up to 3000 m).
SHSNU equipment includes:
Ground equipment.
Fountain fittings.
Wellhead piping.
Rocking machine.
underground equipment.
Pump and compressor pipes.
Pump rods.
Rod well pump.
Various protective devices(gas or sand anchor, filter, etc.)
In a well equipped with a pumping station, fluid is supplied by a deep plunger pump, which is driven by a special drive (pumping machine) by means of a rod string. The pumping unit converts the rotational movement of the electric motor into the reciprocating movement of the rod suspension.
Pumping units - individual mechanical drive SHSN (Table 19).
Table 19
|
Pumping unit |
Number of moves balancer in min. |
Weight, kg |
Reducer |
|
SKD4-2,1-1400 |
|||
|
SKD6-2.5-2800 |
|||
|
SKD8-3,0-4000 |
|||
|
SKD10-3.5-5600 |
|||
|
SKD12-3,0-5600 |
In the code of the machine - rocking chairs of the SKD type, for example SKD78-3-4000, it is indicated: letters - the rocking machine is deaxial, 8 - the maximum allowable load P max on the balancer head at the point of suspension of the rods in tons (1t = 10 kN); 3 - the longest stroke of the wellhead rod in m; 4000 - the highest permissible torque M kr max on the driven shaft of the gearbox in kgf / m (1 kgf / m \u003d 10 -2 kN m).
The pumping unit (Fig. 20) is an individual drive of the borehole pump.
Table 20
|
Pumping unit |
Mouth rod length, m |
Number of rocker swings, min |
Electric motor power, kW |
Weight, kg |
|
|
SKS8-3,0-4000 |
|||||
|
PNSh 60-2,1-25 |
|||||
The main elements of the SC are a frame (21), a rack (8) with a balancer (13), two cranks (15) with two connecting rods (14), a gearbox (16), a V-belt drive (18), an electric motor (19) and a control unit, which is connected to the field power transmission line.
The frame is made of profiled rolled metal in the form of two skids interconnected by crossbars. All the main components of the SC are attached to the frame.
The post is made of profiled rolled steel of a four-leg design with transverse links.
The balancer consists of an arc head (10) and a balancer body (13) of a single block design.
The balancer support creates an articulated connection of the balancer with the crosshead and connecting rods.
The traverse is designed to connect the balancer with two connecting rods operating in parallel.
The connecting rod is a steel tubular billet, which is pressed against the pin at one end, and pivotally against the crosshead at the other.
The crank converts the rotational movement of the driven shaft of the gearbox into a vertical reciprocating movement of the rod string.
The reducer is designed to reduce the speed transmitted from the electric motor to the cranks of the pumping unit. The reducer is two-stage, with a cylindrical chevron gear.
The brake (22) is made in the form of two pads attached to the gearbox.
V-belt transmission connects the electric motor and gearbox and consists of V-belts, a gearbox pulley and a set of quick-change pulleys.
The electric motor is asynchronous, three-phase with increased starting torque, short-circuited, in a closed version.
The rotary slide (23) under the electric motor is used for quick change and tensioning of the V-belts.
The wellhead rod hanger is designed to connect the wellhead rod (7) with the SC. It consists of a rope suspension (12) and upper and lower traverses (9).
To seal the wellhead stock, the X-mas tree is equipped with a stuffing box. The wellhead rod is connected by means of a rod string to the plunger of a deep rod pump.
Downhole rod pumps (OST 26-26-06-86) are reliable and economical production equipment for oil wells, widely used for the selection of reservoir fluid (a mixture of oil, water and gas).
Indicators for the normal operation of rod pumps:
temperature of the pumped liquid - no more than 130 C
water cut of the pumped liquid - no more than 99%
fluid viscosity - no more than 0.025 Pa_s
mineralization of water - up to 10 mg/l
maximum concentration of mechanical impurities - up to 1.3 g/l
concentration of hydrogen sulfide - no more than 50 mg/l
pH value of produced water (pH) 4.2-8
The pump works as follows. When the plunger moves upwards, a vacuum is created in the intervalve space of the cylinder, due to which the suction valve opens (the ball rises from the seat) and the cylinder is filled with the discharge valve closed. With the subsequent downward stroke of the plunger, the intervalve volume is compressed, the discharge valve opens, and the liquid that enters the cylinder flows into the area above the plunger with the suction valve closed. Movements up and down periodically made by the plunger ensure pumping of the reservoir fluid and its injection onto the earth's surface.
Downhole rod pumps are a single-acting vertical single-stage and single-plunger design with a solid fixed cylinder, a movable metal plunger, discharge and suction valves.
· Details of the pump are made of the high-alloyed and special steels and alloys;
· Thick-walled pump cylinder with chrome coating and nitriding 70 HRC, cylinder length 4200mm;
· Plunger made of carbon steel with chrome coating and nitriding 67-71 HRC of the outer surface;
· Non-straightness of the pump 0,08mm on a length of 1000mm;
· The surface roughness of the cylinder and plunger is 0.2 microns;
· Valve couples from material like stellite or tungsten carbide;
On the lower (outer) side of the pump, a pipe thread is cut for hanging a "tail" or additional equipment (filter, HPJ, etc.)
· In the upper part of the pump (not plug-in), a branch pipe 0.5 m long is screwed in with a coupling for working with keys and an elevator when lowering it into the well.
SRPs are produced in two types:
Plug-in
HB1 - plug-in borehole pump with a solid cylinder and an upper locking support.
Non-inserted (pipe)
NN2B - non-plug-in borehole pump with a solid cylinder and a drain valve.
Currently mainly used
Non-inserted pumps of the NN-2B type with a conditional size (plunger diameter) of 32, 44, 57 and 68 mm, as well as
· plug-in pumps NV1B -28, NV1B - 32, NV1B - 44 and NV1B - 57mm with upper lock support.
The symbol includes:
pump type;
execution on the cylinder;
conditional size (plunger diameter) of the pump;
plunger stroke in mm reduced by 100 times;
pump head in m reduced by 100 times;
landing group;
performance in terms of resistance to the environment;
design features;
Examples of pump symbols:
NV1BP - 44-18-12-2-I OST26-16-06-86 - plug-in pump, cylinder type B (thick-walled, sleeveless, solid), for operation with a high sand content (more than 1.3 g / l.) , nominal size (diameter) 44 mm, plunger stroke 1800 mm, head 1200 m, 2 landing groups and wear-resistant to aggressive environment - I.
1 - lock; 2 - stock; 3 - emphasis; 4 - locknut; 5 - plunger cage; 6 - cylinder; 7 - plunger; 8 - discharge valve; 9 - suction valve
NN2B-57-30-12-1 OST 26-16-06-86 - non-plug-in pump, cylinder B design (thick-walled, sleeveless, solid), nominal size (diameter) 57mm, plunger stroke 3000mm, head 1200m, 1 group landing, normal execution on resistance to the pumped-out environment.
1 - cylinder; 2 - stock; 3 - plunger cage; 4 - plunger; 5 - discharge valve; 6 - catcher rod; 7 - suction valve; 8 - cone saddle;
Rod pumps according to OST 26-16-06-86 corresponds to ST - SEV 4355-83, GOST 6444-86.
Table number 21.
|
Pump version |
Conditional dimensions (mm) |
Rod thread (mm) |
Plunger stroke length (mm) |
|
44/28,57/32,70/44 |
|||
Pump type:
HB1 - plug-in with a lock at the top
HB2 - plug-in with a lock at the bottom
NN - non-inserted without catcher
HH1 - non-pluggable with a gripping rod
НН2 - non-inserted with catcher
B - sleeveless pump cylinder
C - pump cylinder with bushings
Pump classification according to design features- Areas of use.
T - with a hollow (tubular) rod, providing liquid lifting through the channel of the hollow rod column
A - with a coupling device (auto coupler) (only for HH) providing coupling of the rod string with the pump plunger.
D1 - single-stage, two-plunger - providing the creation of a hydraulic heavy bottom.
D2 - two-stage, two-plunger - providing two-stage compression of the pumped liquid
U - with an unloaded cylinder (only for HH2) that ensures the removal of a cyclic load from the cylinder during operation.
In the assembled pump, the plunger lubricated with spindle oil should move smoothly and without jamming along the entire length of the cylinder, depending on the landing group indicated in table No. 22.
Plunger displacement force in the pump cylinder (maximum)
Table number 22.
The fit of the plunger in the pump cylinder is characterized by the limiting gaps (per diameter) between the plunger and the cylinder. Depending on the limiting clearances, the pumps are produced in the following landing groups:
"0" group - up to 0.045mm.
"1" group - from 0.020 to 0.070mm
"2" group - from 0.070 to 0.120mm
"3" group - from 0.120 to 0.170mm
Plunger seating groups in the pump cylinder according to the API (American Petroleum Institute) standard.
Table number 23.
|
landing group |
Gap range (mm). |
Input control of rod pumps
Upon receipt of the SRP at NGDU, the pumps undergo incoming control. Entrance control is carried out by the service of the chief mechanic.
Quality and completeness check
· Checking the quality and completeness is carried out in the workshop for the repair of SRP after their transfer from NGDU to Neftepromremont LLC in accordance with the transfer certificate.
· Checking the quality and completeness of the pumps is carried out by competent specialists of NPR LLC, if necessary, in the presence of a representative of the oil and gas production department (owner of the SRP) and a representative of the manufacturer (if serious defects are found) with the preparation of an appropriate bilateral act.
· It is allowed to carry out acceptance of pumps for quality unilaterally with the consent of the manufacturer.
· On the day the pumps are accepted, an act is drawn up, which is signed by all persons participating in the quality control. Attached is a copy of the invoice. The act is approved by the chief engineer of NPR LLC.
· During the quality control of the SRP for external defects, the number indicated in the passport is compared with the actual number stamped on the sub of the bushing cylinder and on the bore of the solid - sleeveless cylinder. In the absence of a factory passport, the actual number of the pump is recorded.
Pumps are rejected in the following cases:
· in case of failure of the plunger to pass into the cylinder (for non-plug-in pumps), connected to a branch pipe made of tubing with a length of at least 1200 mm;
· in case of discrepancy between the number of the plunger and its size indicated in the passport with the actual one, if the number does not match, but the size of the plunger matches, the actual data is entered into the operational passport;
In case of violation of the integrity of the chrome plating coating (delamination, risks, cracks, etc.);
if at least one used part is found in the pump;
if a curvature or curvature of the pump cylinder is detected;
if traces of rough treatment of the surfaces of the cylinder and plunger are found after chromium plating;
· Before sending the SRP to the well, the main components of the pump and the smoothness of the plunger in the cylinder are checked by external inspection.
· In the presence of a jam, jerks, knocks, or the impossibility of passing the plunger along the entire length of the cylinder, the pump is rejected.
· In plug-in pumps, the condition of the support cone, the quality of the assembly, the fastening of the threaded connections and the quality of the seating surface of the lock support are additionally checked. The plunger of the plug-in pump is removed for revision after unscrewing the stop nipple.
· The tightness of the cylinder assembly with the suction valve and the plunger with the delivery valve, for plug-in pumps, assembled with a locking support, is checked by pressing spindle oil at a temperature of 20 C to a pressure of P = 150 atm.
· After checking the completeness and quality of the SRP, an operating passport of the pump is issued to NPR LLC, where data on the date of the check, the results of pressure testing and configuration are entered.
Transportation of SRP to the well
· Rod pumps are delivered to the well on a commercial self-loader PS-0.5, equipped with a rotary hydraulic crane with a lifting capacity of 5 tons, or on any other vehicle that provides loading and unloading and transportation of rod pumps without bending them. To protect the pumps from clogging, special screw plugs (caps) must be installed in the end couplings; for plug-in pumps, the locking support must be protected from damage.
· During transportation, the SRP are installed on the platform of the vehicle in an inclined position, secured from possible movement with special clamps with screw clamps.
· At the well, the pump is unloaded using universal slings and grabs with a crane and placed on a clean horizontal place on 3-4 wooden strips or on walkways. It is strictly forbidden to roll the pump from the platform to the ground, lay it on pipes, rods, wellhead fittings or install it in an inclined position.
Pumps lifted from the well are delivered to NPR LLC also for vehicles intended for transportation of SRP with rigid fastening. Disassembly of the pump on the well is prohibited.
Organization of work during the repair of wells equipped with USP
The wells equipped with USHGN are put into repair on the conclusion of the technological service of the oil field and on the basis of measures on the need for underground repairs.
The reason for the rise of the CSR is the reduction or cessation of supply. The cause of the malfunction must be determined in advance according to the dynamometer chart taken before lifting and noted in the operational passport signed by the oil field technologist.
In the column reason for refusal, the general entry “no filing” is not allowed. The final decision on the change of the SRP is made by the technologist of the TsDNG and a mark in the operational passport. The rigging crew gets on the well to lift the SRP in the presence of a fully completed operational certificate.
The required order and scope of work at wells equipped with CCPPs is formed when drawing up a schedule for the movement of underground well workover teams of OGPD, which is attended by representatives of services and workshops of NGDU (TsITS, PTO, TsDNG, TsNIPR, TsPRS).
The schedule for the movement of brigades of the PRS (KRS) is approved by the chief engineer of the NGDU.
For wells from a frequently repaired well stock (3 or more CSP failures in a rolling year), a separate work plan is drawn up, which is agreed upon by the oil field, TsPRS, LTTND, and when considering the schedule, these wells are included in the movement of crews.
The scope of work is determined based on
study of the operating mode of the failed CPP,
causes of failures of previous installations,
well characteristics,
type of work (change of SHRP, commissioning after drilling, transfer to SHRP)
· gauging of the production string (in the presence of puffs, landings in the process of tripping the equipment of the CSP equipment), it is recommended to lower the template to a depth of 150m above the perforation interval, the diameter of the template is 120mm and the length is 9m;
Scraping of the production casing (when tightening and not passing the template during tripping, hydraulic or mechanical scraper to the depth of the template descent, followed by flushing the wellbore (carried out at least once every three years or when commissioning from inactivity - more than 3 years);
The definition of the current bottom hole is made at the request of the oil field:
after cleaning the bottomhole with a bailer, washing;
· after the accident, “flights” of the USHPU to the bottom of the well;
· in case of frequent failures of the USHGN associated with the ingress of sand, mechanical impurities, paraffin into the pump;
· after work on the development of the formation or work on cleaning the bottomhole formation zone;
Bottomhole cleaning, well flushing:
· after carrying out hydrochloric acid treatments, other treatments of the bottomhole zone;
· according to the results of measuring the current bottomhole of the well;
Workover technology for wells equipped with USP
Repair of wells equipped with SRPs is carried out by specialized repair teams in accordance with the work plan and in accordance with the Rules of Conduct repair work and other regulations.
· Before killing the well, the static level H st and formation pressure R pl are measured. Based on the results of the measurement, the oil field makes a decision on killing or repair without killing (in accordance with the list of wells agreed with UZSO GGTN).
· Killing of wells is carried out in accordance with the instructions for killing wells equipped with USP pumps, which are in force at OAO Tomskneft VNK.
The oilfield is responsible for the reliability of information about the preparedness of the well for killing.
· Killing results are documented in an act indicating the type of killing fluid, its volume, density, pressure and cycles during killing. The act is signed by the killing foreman, transferred to the drilling team and stored together with the start-up documentation for the workover of the well.
· The crew starts the workover of the well only if there is a work plan (work order) approved and agreed by the TsDNG and TsPRS, as well as a fully completed operational passport for the USHPU. The oil field technologist is responsible for the quality of filling out the passport.
Before a well is repaired, it is necessary to carry out the following preparatory work:
§ fix the polished rod with a special clamp;
§ dismantle the rope suspension;
§ tilt the head of the balancer.
After carrying out repair work on the well, the TRS team, in the presence of a representative of the CDNG, must call for the supply and pressurize the tubing with a pump, drawing up an act on the acceptance of the well from repair. With tightness of the tubing and stable operation of the pump, the pumping machine is put into operation.
§ The foreman of the PRS team (KRS) fills out the SRP operational passport indicating all the parameters of the layout of the lowered underground equipment (tubing diameter, rods and number, presence and number of centralizers, filter, HPU, etc.)
The act of handing over the well from repair is signed after 72 hours of non-failure operation of the SRP by a representative of the oil field. The basis for signing the act on the delivery of the well from the repair is the measurement of the well flow rate and the dynamometer record taken after the well was launched. The operating certificate of the SRP is attached to the well repair certificate, which must be kept together with the certificate, and during subsequent repairs, be transferred to the TsPRS with filling in the data on the operation of the pump.
Launch of wells equipped with USP
2 hours before the start of the well, the TRS team confirms the application to call the representative of the oil field. The application is transferred to the dispatcher or oil field technologist.
Reception of wells equipped with CSP from repair is carried out around the clock. On the first shift by the foreman of the TsPRS (KRS) and the foreman of the oil field (or persons replacing them), on the second shift by the senior operator of the PRS and the senior operator of the oil field.
Before starting a well with a USP, check the serviceability of surface equipment:
o at the wellhead - a check valve and gate valves, an echo sounding pipe with free access to it, a sampling valve on the flow line, etc.;
o operability of the Sputnik group metering unit;
o tightness of tubing and SUSG;
The well is launched and put into the mode of the equipped CPP by the oil and gas production operator.
The oil production operator performs all the necessary operations with the wellhead fittings, manifold, AGZU "Sputnik", provides control over the amount of flow from the well and transfers data to the oilfield dispatcher (technologist).
Control over the change in the liquid level in the annulus and dynamometering of wells is carried out by the research operator or the operator of oil production (at least once a day, measurement of Нdin, Рs, and dynamometering).
Responsibility for putting the wells on the regime, timely shutdown of the pumping unit during abnormal modes, or launching when the equipment is not ready (malfunction of the Sputnik AGZU, leakage of gate valves, a non-return valve on the annulus, etc.) is borne by the technological service of the oil field and the foreman of the production team. The decision on how to bring the pump to the mode or stop the pump to eliminate the identified problems is made by the leading technologist of the oil field.
· Before pressure testing of the well, determine the flow, assemble the wellhead stuffing box (SUSG) with a polished rod, install a pressure gauge on the manifold line (scale no more than 100 atm.).
· By reciprocating swinging of the rods with the help of a lifting unit, increase the pressure on the manifold line according to the pressure gauge - 30 atm.
· Monitor the pressure drop on the manometer when the annular valve is open.
USHGN is considered serviceable if, during pressure testing, the pump raises the pressure to 30 atm. and when the swing stops, the pressure drop does not exceed 5 atm. in 15 minutes. At the same time, there should be no gas and liquid leaks in the lower stuffing box and X-mas tree connections.
· After crimping, the polished rod is connected to the suspension traverse and the rocking machine is put into operation.
· Within 2 hours after the launch, the survey operator or the d / n operator needs to measure the well flow rate, the liquid level in the annulus and perform a dynamometer. In the case of a low (high) plunger fit, impact of the upper rod coupling on the SUSG, the PRS team re-adjusts the plunger fit.
· All documents on the well are signed by the foreman and technologist of the oilfield after 72 hours of trouble-free operation of underground equipment, provided that all the remarks of the oilfield, indicated when accepting the well from repair, are eliminated.
When accepting a well from a workover, the following requirements are imposed on the equipment of the SHSNU and the territory of the well:
With the extreme lower position of the head of the balancer, the distance between the traverse of the stuffing rod suspension or the rod holder and the wellhead stuffing box should be no more than 200 mm.
Flange connections of X-mas trees and wellhead piping must be tight and have a complete set of fasteners.
The wellhead and the territory of the well and the SRP equipment must be cleaned of oil contamination, and the territory of the well cluster must be cleared of pipes, rods and equipment used in the workover of the well.
Bringing wells equipped with CSP to production
The purpose of the operation to bring the well from the CPP to the mode is to ensure the pump's operability in the initial period of putting the well into operation after repair.
Before launching a well equipped with USP
check the readiness of ground equipment,
measure the static level and
· run the installation.
In the operational passport, note the time of the appearance of the filing.
Measure the flow of the well (Qzh) using the AGZU "Sputnik", compare it with the theoretical performance of the lowered pump; then a dynamogram is taken and a sample of the liquid is taken.
In the initial period after the launch of the CPP, regular monitoring of the feed rate and the rate of decrease in the dynamic level is carried out. It is not allowed to pump the level lower than 200m above the pump intake.
When the well is put into operation, the frequency of measurements is H dyn. and Q w should be determined by the technological service for each well individually.
The value of the dynamic level in the well and the performance of the CPP is determined using an echo sounder and a dynamograph.
AT winter time, in cases of a long shutdown of the well for inflow, measures should be taken to prevent freezing of the reservoir.
The time of bringing to the mode is determined for each well individually.
The well is considered to be put into operation if the results of 3 measurements of the dynamic level performed with an interval of at least 1 hour are close in value at a constant productivity.
The executor of work on bringing the well to the regime with the CSP (the production operator or the operator for the study) shall transmit information to the oilfield dispatcher on a shift basis.
After bringing the well to the mode with USHGN, after 1 day, perform
Measurement of the dynamic level H dyn.,
well productivity Q w,
· Sampling of fluids for watering of products and content of mech. impurities
remove the dynamometer.
Fill in the appropriate columns of the operational passport for the CCPP to put it into operation, if necessary, with the attachment of supporting documents (dynamograms, measurement results, etc.).
Operation of wells with USP
· After bringing the well to the steady state, the oil field submits an application for work on additional balancing of the pumping unit.
· Within two days from the moment of launching the CPP, the oil field controls its work. In the future, control over the operation of the well is carried out by dynamometers, measurements of fluid production, wellhead pressures and dynamic level.
· During the first two weeks of operation of the CPP, the oilfield conducts a set of studies on the well in order to determine the optimal operating mode of the lowered pump.
· Any change in operating modes of a well equipped with a CSP should be justified by calculations. The oil field technologist is responsible for timely calculations and systematic changes in the operating mode of the CPP.
The permanent commission for the investigation of premature failures of the USPPP investigates the causes of failures of pumps with an operating time of up to 100 days.
Periodicity of control over the work of wells with USP
Table No. 24
|
Controlled parameter |
Control method |
Frequency of control |
|
1. Boom loads and feed |
Dynamometer |
After starting the well and putting it into operation When changing the operating mode Before PRS Current control at least 2 times a month. |
|
Fluid flow rate measurement from one temporary mark of the level. |
According to AGZU counters and wavemeters. |
After launch and output to the mode of wells. When changing the operating mode. Before PRS. |
|
Liquid sampling for water cut (%) |
After the well to the mode. When changing the operating mode. Current control at least 1 time per month. |
|
|
4. Sampling at EHF |
After starting and bringing the well to the mode. 4.2. Current control at least 1 time per month. |
Operational data must be entered in a timely manner in the operational passport of the USHPU, the oilfield technologist is responsible for filling out the passport.
Most of the production well stock of oil companies is equipped with sucker rod pumping units. Control of the operation of rod pumps is carried out, as is known, by means of dynamometers. That is, by removing the diagram of the change in the load on the wellhead rod when it moves up and down.
The skill of reading dynamometer charts, the ability to interpret them correctly is necessary for both the specialists of the technological service of an oil producing enterprise and the specialists of the geological service.
For process engineers, dynamometer charts help in making decisions about the need current repair well (TRS) or, for example, the need for hot treatment of the well to remove paraffin deposits without the involvement of the TRS team.
Geological service specialists need the ability to read dynamometer charts as the very first step in the analysis of the reasons for the decrease in the flow rate of a production well. If the dynamogram is "working", then it's not the pump. This means that we can proceed to the search for "geological" reasons for the decline in production.
Theoretical dynamogram
Before proceeding to the analysis of real dynamometer charts, it is necessary to understand the theoretical dynamometer chart.
As is known, dynamogram- this is a diagram of the change in the load on the wellhead rod, depending on its stroke. Theoretical dynamogram- this is such an idealized dynamometer chart that does not take into account the friction forces, inertial and dynamic effects that occur in real conditions. Due to such effects, the straight lines of the theoretical dynamometer turn into wavy lines characteristic of the real one. Also, in the theoretical dynamometer chart, the rod pump cylinder is assumed to be completely filled, that is, the pump delivery coefficient is 1, which never happens in real conditions (the pump delivery coefficient is usually less than one).
The theoretical dynamogram has the shape of a parallelogram (Figure 1).
Figure 1. Theoretical dynamogram
Figure 2. Schematic of SRP
Dot BUT on the dynamogram, this is the lowest position of the pump plunger. Line segment AB- upward stroke of the polished rod. In this case, deformation (stretching) of the rods occurs, but the pump plunger is still in its lowest position. Line segment BC- upward stroke of the polished rod and plunger of the pump.
Dot C- extreme upper position of the pump plunger. Line segment CD- stroke down polished rod. In this case, the deformation (compression) of the rods occurs, but the pump plunger is still in its uppermost position. Line segment DA- down stroke polished rod and pump plunger
In general, nothing complicated. The left part of the dynamogram characterizes the operation of the pump when the plunger is in the lower position and, accordingly, the operation of the suction valve of the pump. The right part of the dynamogram shows the operation of the pump when the plunger is in the upper position and, accordingly, the operation of the discharge valve of the pump.
Having on hand a dynamogram of the operation of the pump, it is possible to calculate the flow rate of the well fluid. The dynamograph, with which dynamograms are taken, also provides information on the number of swings (per minute) of the pumping unit and the length of the plunger stroke. Knowing which pump is lowered into the well, it is not difficult to calculate the flow rate. Formula for calculation theoretical liquid flow rate:
Q t = 1440 · π /4 · D² · L · N
where
Q t- liquid flow rate (theoretical), m 3 / day
D– plunger diameter, m
L– stroke length, m
N- number of swings, swing / min.
The length of the stroke and the number of swings, as I said, are given to us by the dynamograph together with the dynamometer. The plunger diameter is usually listed in the pump name. For example, for the pump NGN-2-44, the plunger diameter is 44 mm, for NGN-2-57, respectively, 57 mm.
In order to receive actual well fluid flow rate, it is necessary to multiply the result obtained by the formula by the pump delivery coefficient ( η ), which, as we already know, is always less than unity.
Examples of real dynamometers
Actual dynamometer charts come in a huge number of shapes and varieties. It will not be possible to consider all of them here, I will give only a few typical examples:
Influence of gas, incomplete filling of the plunger
Both valves not working
Breakage or lapel rods
Plunger exit from the pump cylinder
Paraffin deposits
Before finishing the article, let's consider one more question:
How often are dynamograms taken?
The policy of various oil companies regarding the frequency of taking dynamograms may differ. But, as a rule, dynamograms are taken once a month on an ordinary, uncomplicated well stock.
If necessary, dynamograms are taken more often (for example, once a week) on a well stock complicated by frequent paraffin deposits. Also, dynamometers are removed if there are appropriate indications (as they say medical workers). For example, with a decrease in the flow rate of the well fluid, with an increase in the dynamic level, after changing the operating parameters of the rod pump (stroke length, number of swings), and others.
If geological and technical measures (GTO) were carried out on the well, then after the well is launched, until it enters the mode, dynamometer charts are taken, as a rule, daily. The same can be said about new wells launched from drilling.
Rod downhole pumping units (SHSNU) are designed to lift reservoir fluid from a well to the surface.
Over 70% of the operating well stock is equipped with downhole pumps. With their help, about 30% of oil is produced in the country.
At present, SHSNU, as a rule, is used in wells with a flow rate of up to 30 ... 40 m 3 of fluid per day, less often up to 50 m 3 at average suspension depths of 1000 ... 1500 m. m 3 / day.
In some cases, pump suspension can be used to a depth of 3000 m.
The drive is designed to convert the engine energy into reciprocating motion of the sucker rod string.
Rod borehole pumping unit includes:
a) ground equipment - pumping unit (SK), wellhead equipment, control unit;
b) underground equipment - tubing (tubing), pumping rods (SHN), sucker rod pump (SHSN) and various protective devices that improve the operation of the installation in difficult conditions.
Rice. 1. Rod downhole pumping unit:
1 - foundation; 2 - frame; 3 - electric motor; 4 - cylinder; 5 - crank; b - cargo; 7 - connecting rod; 8 - cargo; 9 - rack; 10 - balancer; 11 - mechanism for fixing the head of the balancer; 12 - balancer head; 13 - rope suspension; 14 - polished rod;
15 - wellhead equipment; 16 - casing string; 17- pumping and compressor pipes; 18 - column of rods; 19 - deep pump; 20 - gas anchor; 21 - polished rod seal; 22 - pipe coupling; 23 - rod coupling; 24 - deep pump cylinder; 25 - pump plunger; 26 - discharge valve; 27 - suction valve.
A pump cylinder is lowered into the well on the tubing string under the liquid level. Then, on the pump rods, a piston (plunger) is lowered into the tubing, which is installed in the pump cylinder. The plunger has one or two valves that open only upwards, called pop-up valves. The upper end of the rods is attached to the head of the rocker balancer. To direct fluid from the tubing to the oil pipeline and prevent its spill, a tee is installed at the wellhead and a stuffing box above it, through which the stuffing box is passed.
Upper stem, called a polished rod, is passed through the stuffing box and connected to the head of the balancer of the pumping unit using a rope suspension and a traverse.
plunger pump is powered by a pumping unit, where the rotational motion received from the engine using a gearbox, a crank mechanism and a balancer is converted into a reciprocating motion transmitted to the rod pump plunger through the rod string.
When the plunger moves up under it, the pressure decreases, and the liquid from the annular space through the open suction valve enters the pump cylinder.
When the plunger moves down the suction valve closes, and the discharge valve opens, and the liquid from the cylinder passes into the riser pipes. With continuous operation of the pump, the liquid level in the tubing rises, the liquid reaches the wellhead and overflows through the tee into the flow line.
Drives PO "Uraltransmash"
Conventional designation of drives on the example of PShGNT4-1.5-1400:
PShGN - drive of sucker rod pumps;
T - the reducer is installed on the pedestal;
1.5 - the maximum stroke length of the wellhead rod is 1.5 m;
1400 - the highest allowable torque on the driven shaft of the gearbox;
Lecture No. 2
Purpose, types, design and marking of borehole
Rod pumps.
Downhole rod pumps are designed for pumping out from oil wells liquid with water cut up to 99%, temperature up to 130°C, hydrogen sulfide content not more than 50 mg/l, water salinity not more than 10 g/l.
Borehole pumps are of vertical single acting design with fixed cylinder, movable metal plunger and ball valves. Pumps are manufactured in the following types:
1) HB1 - plug-in with a lock at the top;
2) HB2 - plug-in with a lock at the bottom;
3) NN - non-inserted without catcher;
4) HH1 - non-inserted with a gripping rod;
5) HH2 - non-inserted with catcher
| Rice. 2. Non-inserted borehole pumps |
The HH1 pump consists of a cylinder, plunger, discharge and suction valves. In the upper part of the plunger there is a discharge valve and a rod with a sub for the rods.
A suction valve is freely suspended from the lower end of the plunger by means of a tip on the gripping rod. During operation, the valve is seated in the seat of the body. Hanging the suction valve from the plunger is necessary to drain the fluid from the tubing before lifting them, as well as to replace the valve without lifting the tubing. The presence of the gripping rod inside the plunger limits the length of its stroke, which in HH1 pumps does not exceed 0.9 m.
In the HH2C pump, unlike the HH1 pump, the discharge valve is installed at the lower end of the plunger. To remove the suction valve without lifting the tubing, a catcher (bayonet lock) is used, which is attached to the discharge valve seat. The catcher has two curly grooves for engagement. A spindle (short stem) with two thickened studs is screwed into the suction valve cage. After the suction valve is seated in the body seat, by turning the rod string 1-2 turns counterclockwise, the spindle studs slide along the catcher grooves and the suction valve is disconnected from the plunger. The capture is carried out after the plunger is seated on the spindle when the rod string is rotated clockwise.
The NNBA pump allows forced withdrawal of fluid from wells through tubing, the diameter of which is smaller than the diameter of the plunger.
This is achieved by its special design - the presence of an automatic coupler, including a coupler and a grip, and drain device. The assembled pump without a coupler is lowered into the well on the tubing. Then a hitch with a measuring rod is lowered on the bars. The clutch pushes the spool of the drain device down and engages with the grip attached to the plunger, while the drain hole closes. When lifting the pump, raise the rod string. At the same time, the gripper pushes the spool up, opening the drain hole. After that, the hitch is separated from the grip and the column of rods rises freely.
Insertion pump cylinder(see Fig. 3) is lowered inside the pipes on the column of rods and mounted on them using a special locking connection. This allows the insertion pump to be changed without running in and out of pipes. But with the same diameters of the plungers, the plug-in pump requires the use of tubing of a larger diameter.
Downhole pumps of NV1S version are designed for pumping low-viscosity liquid from oil wells.
The pump consists of a composite cylinder on the lower end of which a double suction valve is screwed, and on the upper end - a plunger lock movably located inside the cylinder, on the threaded ends of which are screwed: a double discharge valve from below, and a plunger cage from above. To connect the plunger to the pump rod string, the pump is equipped with a rod screwed onto the plunger cage and secured with a lock nut. In the bore of the upper sub of the cylinder there is a stop, resting on which the plunger ensures the downhole pump is torn off the support.
Downhole pumps NV1B. These pumps, in terms of purpose, design, and operating principle, are similar to pumps of the NV1S version and differ from them only in that the cylinder used is solid cylinders of the Central Bank version, which are characterized by increased strength, wear resistance and transportability compared to the cylinders of the TsS version.
Downhole pumps of the HB2 version have a field of application similar to that of the downhole pumps of the HB1 version, however, they can be lowered into wells to a greater depth.
| Rice. 3. Downhole pumps |
A stop nipple with a cone is screwed onto the suction valve. At the upper end of the cylinder there is a safety valve that prevents sand from settling in the cylinder when the pump is stopped.
A plunger with a pressure valve at the lower end and a plunger cage at the upper end is movably mounted inside the cylinder. To connect the pump plunger to the pump rod string, the pump is equipped with a rod screwed onto the plunger cage and locked with a lock nut.
A stop is located in the bore of the upper end of the cylinder.
The pump is lowered into the tubing string on the sucker rod string and fixed in the support by the lower part with the help of a thrust nipple with a cone. This fastening of the pump allows you to unload from pulsating loads.
This circumstance ensures its application at great depths of wells.
cylinders borehole pumps are produced in two versions:
® CB - one-piece (sleeveless), thick-walled;
® TsS - composite (sleeve).
The cylinder of the bush pump consists of a casing in which bushings are placed. The bushings are fixed in the casing with nuts.
The bushings are subjected to a variable internal hydraulic pressure caused by the pumped liquid column and a constant force resulting from the end compression of the working bushings. Bushings of all pumps with different internal diameters have the same length - 300 mm each.
The bushings of all pumps are made of three types: alloyed from steel grade 38HMYUA, steel from steel grades 45 and 40X, cast iron grades SCh26-48.
Alloy bushings are made only thin-walled, steel - thin-walled, with increased wall thickness and thick-walled, cast iron - thick-walled.
To increase the durability, the inner surface of the bushings is strengthened by physico-thermal methods: cast iron bushings are hardened with high-frequency currents, steel bushings are nitrided, cemented, nitrated. As a result of this treatment, the hardness of the surface layer is up to 80 HRc.
The machining of bushings consists of grinding and honing. The main requirements for machining are a high class of accuracy and cleanliness of the inner surface, as well as the perpendicularity of the ends to the axis of the bushings.
Macrogeometric deviations of the inner diameter of the sleeve should be no more than 0.03 mm. The flatness of the end surfaces must provide a uniform continuous spot on the paint of at least 2/3 of the bushing wall thickness.
Seamless cylinders are a long steel pipe, the inner surface of which is working. In this case, the pipe plays the role of both the cylinder and the casing at the same time. Such a design is devoid of such disadvantages as leakage between the ends of the working bushings, curvature of the cylinder axis. This increases the rigidity of the pump and makes it possible to use a large-diameter plunger with the same outer diameter compared to a sleeve pump.
Plunger deep pump is steel pipe with internal thread at the ends. For all pumps, the plunger length is constant and is 1200 mm. They are made of steel 45, 40X or 38HMYUA. According to the method of sealing the gap between the cylinder and the plunger, a distinction is made between fully metal and rubber-lined plungers. In a pair of metal plunger - cylinder, the seal is created by a normalized gap of great length, in rubberized ones - due to cuffs or rings made of elastomer or plastic.
Currently, plungers are used (Fig. 4):
a) with a smooth surface;
b) with annular grooves;
c) with a helical groove;
d) with annular grooves, a cylindrical bore and a beveled end in the upper part (“sand breeze”);
e) collar plungers;
e) rubberized plungers.
a - smooth (version G); b - with annular grooves (version K); c - with a helical groove (version B); g - type "sand shave" (version P); d - cuff, rubberized plunger; 1 - plunger body; 2 - self-sealing rubber ring; 3 - swelling rubber rings.
Sucker rods
Pump rods are designed to transfer reciprocating motion to the pump plunger (Fig. 5). Manufactured mainly from alloy steels round section diameter 16, 19, 22, 25 mm, length 8000 mm and shortened - 1000, 1200, 1500, 2000 and 3000 mm for both normal and corrosive operating conditions.
Rice. 5 - Sucker rod
Rod code - ШН-22 means: pump rod with a diameter of 22 mm. Steel grade - steel 40, 20N2M, 30KhMA, 15NZMA and 15Kh2NMF with a yield strength of 320 to 630 MPa. Sucker rods are used in the form of columns made up of individual rods connected by couplings.
Rod couplings are produced: connecting type MSH (Fig. 6) - for connecting rods of the same size and transfer type MSHP - for connecting rods of different diameters.
To connect the rods, couplings are used - MSH16, MSH19, MSH22, MSH25; the figure means the diameter of the connected rod along the body (mm). Ocher Machine-Building Plant JSC manufactures pump rods from uniaxially oriented fiberglass with a tensile strength of at least 800 MPa. The ends (nipples) of the rods are made of steel. Rod diameters 19, 22, 25 mm, length 8000 - 11000 mm.
Rice. 6 – Sucker rod coupling:
a - execution I; b – execution II
Advantages: 3-fold weight reduction of the rods, reduction of energy consumption by 18-20%, increased corrosion resistance with a high content of hydrogen sulfide, etc. Continuous rods "Korod" are used.
Oil production with rod pumps is the most common method of artificially lifting oil, which is explained by their simplicity, efficiency and reliability. At least two thirds of the existing production wells are operated by SRP units.
in front of others by mechanized methods oil production units have the following advantages:
- have a high efficiency;
- repair is possible directly at the fields;
- different drives can be used for prime movers;
- SRP units can be used in complicated operating conditions - in sand-producing wells, in the presence of paraffin in the produced oil, with a high GOR, when pumping out a corrosive liquid.
Rod pumps also have disadvantages. The main disadvantages include:
- limitation on the depth of the pump descent (the deeper, the higher the probability of rod breakage);
- low pump flow;
- restriction on the inclination of the wellbore and the intensity of its curvature (not applicable in deviated and horizontal wells, as well as in highly deviated vertical ones)
A deep-well rod pump in its simplest form (see figure on the right) consists of a plunger moving up and down a well-fitting cylinder. The plunger is provided check valve, which allows the liquid to flow up but not down. The non-return valve, also called a poppet valve, in modern pumps is usually a ball-and-seat valve. The second suction valve is a ball valve located at the bottom of the cylinder and also allows liquid to flow upwards but not downwards.
Rod pump refers to a positive displacement pump, the operation of which is provided by the reciprocating movement of the plunger with the help of a ground drive through a connecting body (rod string). The top bar is called polished stem, it passes through the stuffing box at the wellhead and is connected to the balance head of the pumping unit using a traverse and a flexible rope suspension.
The main units of the USHGN drive (pumping unit): frame, stand in the form of a truncated tetrahedral pyramid, 6 balancer with a swivel head, a traverse with connecting rods hinged to the balance bar, a gearbox with cranks and counterweights, are equipped with a set of interchangeable pulleys to change the number of swings. For quick change and tension of belts, the electric motor is mounted on a rotary slide.
Rod pumps are plug-in (NSV) and non-inserted (NSN).
Plug-in rod pumps are lowered into the well in assembled form. Beforehand, a special locking device is lowered into the well on the tubing, and the pump on the rods is lowered into the already lowered tubing. Accordingly, to change such a pump, it is not necessary to once again lower and raise the pipes.
Non-insert pumps are lowered semi-disassembled. First, the pump cylinder is lowered onto the tubing. And then a plunger with a check valve is lowered on the rods. Therefore, if it is necessary to replace such a pump, it is necessary to lift the plunger on the rods from the well first, and then the tubing with the cylinder.
Both types of pumps have their advantages and disadvantages. For each specific condition, the most suitable type is used. For example, subject to the content in oil a large number paraffin, it is preferable to use non-inserted pumps. Paraffin deposited on the tubing walls can block the possibility of lifting the plug pump plunger. For deep wells, it is preferable to use an insert pump to reduce the time required to trip the tubing when changing the pump.
In short, two main processes take place inside:
separation of gas from liquid- Ingress of gas into the pump may impair its operation. For this, gas separators are used (or a gas separator-disperser, or just a disperser, or a double gas separator, or even a double gas separator-disperser). In addition, for the normal operation of the pump, it is necessary to filter out the sand and solid impurities that are contained in the liquid.
rise of liquid to the surface- the pump consists of many impellers or impellers, which, rotating, impart acceleration to the liquid.
As I already wrote, electric centrifugal submersible pumps can be used in deep and inclined oil wells (and even in horizontal ones), in heavily watered wells, in wells with iodine-bromide waters, with high salinity of formation waters, for lifting hydrochloric and acid solutions. In addition, developed and produced electric centrifugal pumps for simultaneous-separate operation of several horizons in one well. Sometimes electric centrifugal pumps are also used to pump saline formation water into an oil reservoir in order to maintain reservoir pressure.
The assembled ESP looks like this:
After the liquid is raised to the surface, it must be prepared for transfer to the pipeline. The products coming from oil and gas wells are not, respectively, pure oil and gas. Formation water, associated (petroleum) gas, solid particles of mechanical impurities (rocks, hardened cement) come from wells along with oil.
Produced water is a highly mineralized medium with a salt content of up to 300 g/l. The formation water content in oil can reach 80%. Mineral water causes increased corrosive destruction of pipes, tanks; solid particles coming from the flow of oil from the well cause wear on pipelines and equipment. Associated (petroleum) gas is used as raw material and fuel. It is technically and economically expedient to subject oil to special treatment before it is fed into the main oil pipeline in order to desalt it, dehydrate it, degas it, and remove solid particles.
First, oil enters automated group metering units (AGZU). From each well, through an individual pipeline, oil is supplied to the AGZU along with gas and formation water. The AGZU takes into account the exact amount of oil coming from each well, as well as primary separation for the partial separation of formation water, oil gas and mechanical impurities with the direction of the separated gas through the gas pipeline to the GPP (gas processing plant).
All data on production - daily flow rate, pressure, etc. are recorded by operators in the cult house. Then these data are analyzed and taken into account when choosing a production mode.
By the way, readers, does anyone know why the cult house is called that?
Further, the oil partially separated from water and impurities is sent to the complex oil treatment unit (UKPN) for final purification and delivery to the main pipeline. However, in our case, the oil first passes to the booster pumping station (BPS).
As a rule, BPS are used in remote fields. The need to use booster pumping stations is due to the fact that often in such fields the energy of the oil and gas reservoir is not enough to transport the oil and gas mixture to the UKPN.
Booster pumping stations also perform the functions of separating oil from gas, cleaning gas from dropping liquid and subsequent separate transportation of hydrocarbons. The oil is pumped centrifugal pump, and the gas is under separation pressure. DNS differ in types depending on the ability to pass through various liquids. A full-cycle booster pumping station consists of a buffer tank, an oil leakage collection and pumping unit, a pumping unit itself, and a group of candles for emergency gas discharge.
In oilfields, after passing through group metering units, oil is taken into buffer tanks and, after separation, enters the buffer tank in order to ensure a uniform flow of oil to the transfer pump.
UKPN is a small plant where oil undergoes final preparation:
- Degassing(final separation of gas from oil)
- Dehydration(destruction of the water-oil emulsion formed during the lifting of products from the well and its transport to the UKPN)
- Desalting(removal of salts by adding fresh water and re-dehydration)
- stabilization(removal of light fractions in order to reduce oil losses during its further transportation)
For more effective preparation, chemical, thermochemical methods, as well as electrical dehydration and desalination are often used.
Prepared (commercial) oil is sent to the commodity park, which includes tanks of various capacities: from 1,000 m³ to 50,000 m³. Further, the oil is fed through the main pumping station to the main oil pipeline and sent for processing. But we'll talk about that in the next post :)
In previous releases:
How to drill your well? The Basics of Oil and Gas Drilling in One Post -