阅读说明：本技术 一种注聚井洗井装置及洗井方法 (Polymer injection well washing device and well washing method ) 是由 吏锋兵 屈人伟 韩保锋 雷兵 张清波 王志刚 蔡微微 李志华 王金生 于 2021-08-20 设计创作，主要内容包括：本发明涉及油田注入井井筒清洗技术领域,特别涉及一种注聚井洗井装置及洗井方法。其装置包括洗井池,所述的洗井池通过高压管线分7别连接套管闸门和油管闸门,洗井池包括接收池、循环剪切池和存放池,本发明的一种注聚井洗井装置及洗井方法,通过科学合理的洗井方法,解除井筒炮眼附近的老化聚合物堵塞,恢复注聚井注入能力。同时将洗出的老化聚合物通过经济高效的物理剪切、粉碎方法,达到回注或调剖的要求,用于回注或调剖。这样既能减轻环保压力,又可用于调剖,改善注聚效果的同时又实现废弃物循环利用,符合油田绿色低碳、可持续发展的要求。(The invention relates to the technical field of cleaning of wellshafts of injection wells of oil fields, in particular to a polymer injection well cleaning device and a well cleaning method. The device comprises a well washing pool, wherein the well washing pool is respectively connected with a casing pipe gate and an oil pipe gate through a high-pressure pipeline 7 and comprises a receiving pool, a circulating shearing pool and a storage pool. Meanwhile, the washed aged polymer meets the requirements of reinjection or profile control by an economical and efficient physical shearing and crushing method and is used for reinjection or profile control. Therefore, the method can reduce the environmental protection pressure, can be used for profile control, improves the polymer injection effect, realizes the recycling of wastes, and meets the requirements of green, low carbon and sustainable development of oil fields.)

1. The polymer injection well washing device comprises a well washing pool, wherein the well washing pool is respectively connected with a sleeve pipe gate and an oil pipe gate through a high-pressure pipeline, and is characterized in that the well washing pool comprises a receiving pool, a circulating shearing pool and a storage pool, the receiving pool is used for receiving downhole eluate, a submersible pump is installed in the receiving pool and injects a washing water solution with the downhole eluate in the receiving pool into the circulating shearing pool, a rotary shearing pump and a rod pump are arranged in the circulating shearing pool, the rod pump injects the sheared washing water solution into the storage pool through a pipeline, and the storage pool is internally provided with the rod pump and is used for pumping the washing water solution in the storage pool into a sewage tank truck and pulling the washing water solution to a profile control well for profile control.

2. The polymer injection well washing device according to claim 1, wherein three sets of rotary shear pumps are connected in series in the circulating shear tank.

3. The polymer injection well washing device according to claim 1, wherein a flow meter and a pressure gauge are arranged on the high-pressure pipeline.

4. A polymer injection well flushing method comprises the following steps:

A. stopping injecting the polymer mother liquor, and injecting the oil field water for 1-2 days;

B. cleaning the polymer;

C. injecting the flowback liquid after well washing into a well washing pool through a high-pressure pipeline for polymer treatment, wherein the pasty liquid after the polymer treatment is used for profile control;

D. after the well washing is finished, oil field water is injected for 1-2 days;

E. the polymer is injected normally.

5. The polymer injection well flushing method according to claim 4, wherein the step B specifically comprises:

b1, cleaning residual polymer and attached polymer in the pipe column by circulating flushing of oil field water;

b2, circulation cleaning polymer attached in the well bore and aging polymer near the blast hole.

6. The polymer-injected well washing method according to claim 5, wherein the step B2 specifically comprises:

b21, and a formation micro-leakage well-flushing stage:

controlling the water quantity from the well mouth to be larger than that of the outlet, and adjusting the water quantity of the inlet to be 7m³H, controlling the water quantity at the outlet to be less than 7m³H, reverse circulation well washing for 30min, and the water quality to be discharged does not contain polymerAfter the mud and the sand are mixed, when the water quantity at the outlet is unchanged and the well washing pressure is constant, entering the next well washing stage;

b22, and a stratum micro-jet well-flushing stage:

controlling the water inflow of the well mouth to be less than the water amount of the outlet, and adjusting the water amount of the inlet to be 7m³H, controlling the water outlet quantity to be more than 7m³H; the flow rates at the outlet are respectively 7.5 m, 8.0 m and 8.5m³Flushing each well for 30min at the flow rate of/h, and entering the next well flushing stage when the water quantity at the outlet is unchanged and the well flushing pressure is constant;

b23, balance well washing stage:

at the stage, the outlet water quantity and the stratum discharge quantity are unchanged, the well flushing pressure is prolonged along with the well flushing time, and the well flushing pressure is slowly reduced; when the well washing pressure is reduced to be within 2MPa, the next stage is carried out;

b24, repeating the well washing stage:

repeating the steps B22 and B23, wherein the repetition times depend on the amount of the polymer spitted out from the stratum; when the polymer discharged from the stratum is less and less or even no, and when the water quantity at the outlet and the discharge quantity of the stratum are not changed, the well flushing pressure is prolonged along with the well flushing time, and the well flushing pressure is slowly reduced; when the well washing pressure is reduced to be within 2MPa, the next stage is carried out;

b25, stable well washing stage:

keeping stratum micro-leakage, controlling the water inflow quantity of the wellhead to be larger than the water quantity of the outlet, and adjusting the water quantity of the inlet to be 7m³H, controlling the water quantity at the outlet to be less than 7m³And h, performing reverse circulation well washing for 30min, and finishing well washing after the water at the outlet does not contain polymers and silt.

7. The polymer injection well washing method as claimed in claim 4, wherein in the step C, the polymer is treated by precipitating, filtering and crushing the washed polymer clot in a well washing tank to form a paste, and then the paste is sent to a water injection well needing to adjust the water absorption profile to be used as a profile control agent.

Technical Field

The invention relates to the technical field of cleaning of wellshafts of injection wells of oil fields, in particular to a polymer injection well cleaning device and a well cleaning method.

Background

The principle of polymer flooding for improving recovery efficiency is a technology for improving displacement efficiency by improving oil-water fluidity ratio and enlarging swept volume so as to improve oil recovery speed. Since the lead test of polymer injection was developed in 1990, more than 20 blocks of island oil fields were put into polymer injection development, and polymer injection becomes a mature technology for improving recovery efficiency, and is popularized and applied at home and abroad at present. With the prolonging of polymer injection time, the injection difficulty caused by the polymer blockage problem is increased, which is mainly reflected in that the injection speed and strength are reduced, so that the liquid supply of an oil well is poor, the number of low-liquid wells of the oil well is increased, and the polymer drive effect is seriously restricted. The method adopts the measures of operating and replacing the tubular column aiming at the polymer injection blocked well, but still has the problems of short effective period, high cost and incapability of effectively treating the polymer returned by well washing, and partial wells can only be shut down. Flushing is a relatively cost effective way to plug injection wells, including water injection or polymer injection wells.

The existing well washing mode is mainly used for washing a water injection well and mainly comprises 4 types of well washing vehicle well washing, fixed flow well washing, movable pipeline well washing and tank car well washing, and the essence of the 4 types of methods is that a circulation flow is additionally established to treat well washing return liquid, so that a blockage in the return liquid can not enter a shaft, and the shaft is cleaned. But also has disadvantages. Firstly, without proper means, the outlet pressure control is not stable, which is very easy to cause the formation pressure excitation to form formation sand flow back spitting. Secondly, a proper well washing flow method is not formed, the operation process is more empirical, and the well washing effect is not obviously unstable. Thirdly, the aging polymer of the return liquid has no environment-friendly, economical and efficient disposal means, and the well washing is discontinuous and poor in well washing effect due to the fact that the polymer is only loaded by a tank truck.

In addition, the return is primarily aged polymer, for which disposal is generally chemically degraded with a depolymerizing agent. Preparing a working solution with a certain concentration from a depolymerizing agent, injecting the working solution into a stratum by using a pump truck, closing a well under the stratum condition, reacting for a period of time, washing the well, and normally injecting the polymer. The depolymerizing agent is generally a strong oxidant and has certain dangerousness, particularly, after the depolymerizing agent reacts with a polymer, a byproduct is generally generated with oxygen, if natural gas exists at the bottom of a well, the oxygen is mixed with the natural gas and is exploded when the concentration of the natural gas exceeds a certain concentration, and potential safety hazards are brought to production. The chemical degradation polymer has high investment cost except risk, and the current depolymerizing agent develops towards the direction of biodegradation and slow reaction. In general, there is currently no more efficient disposal solution for how to dispose of aged polymer that is returned from a field wash.

The production of aged polymer occurs in oil and water wells. The polymer aged on the water well is mainly a certain amount of fish eyes generated during the dispersion and curing of the polymer and the polymerization reaction products of the polymer solution crosslinking reaction products and residual monomers in the polymer caused by the high-valence metal ions injected into the water. After the products are dehydrated, plugs with high strength, large elasticity and large particle size are formed and are gathered near blastholes for a long time to cause polymer blockage, so that the injection capability is reduced or injection is stopped, and the injection polymerization effect is influenced. In addition, because of the high permeability strips of the oil-water well, the aged polymer can migrate along the high permeability strips to the vicinity of the blast hole of the oil well and accumulate and even enter the pump barrel, thereby causing the liquid supply capacity to be reduced or the well to be stopped. These aged polymers are currently difficult to reinject and cannot be discharged outside, which not only affects production, but also causes environmental protection pressure.

The Daqing oil field provides a polymer injection well washing standard, namely a polymer injection well washing method. The method aims to remove polymer blockage near pipelines, mineshafts and blastholes and improve the viscosity and injection quality of well heads in a step-by-step and sectional well washing mode. The method comprises the following steps: firstly, stopping injecting mother liquor, and changing water injection to ensure subsequent water consumption; in the second step, residual polymer in the trunk line and polymer attached to the pipeline are washed by oil field water; thirdly, emptying the bottom pressure of the well to ensure the safety of well washing, and discharging oil layer pollutants in the near-wellbore region by using pressure drop; fourthly, removing the pollutants returned from the bottom of the well in one step, and removing the pollutants attached to the blast hole and the four walls of the oil pipe; the fifth step is to restore the normal polymer injection. However, this approach does not address the problem of controlling the well-flushing process and disposing of the returning aged polymer in a targeted manner.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a polymer injection well washing device and a well washing method, which can relieve aged polymer blockage near a borehole blasthole and recover the injection capacity of a polymer injection well. Meanwhile, the washed aged polymer meets the requirements of reinjection or profile control by an economical and efficient physical shearing and crushing method and is used for reinjection or profile control.

The technical scheme adopted by the invention is as follows:

a polymer injection well washing device comprises a well washing pool, wherein the well washing pool is respectively connected with a sleeve pipe gate and an oil pipe gate through a high-pressure pipeline and comprises a receiving pool, a circulating shearing pool and a storage pool, the receiving pool is used for receiving bottom hole eluate, a submersible pump is installed in the receiving pool and injects a washing water solution with the bottom hole eluate in the receiving pool into the circulating shearing pool, a rotary shearing pump and a rod pump are arranged in the circulating shearing pool, the rod pump injects the sheared washing water solution into the storage pool through a pipeline, and the rod pump is arranged in the storage pool and is used for pumping the washing water solution in the storage pool into a sewage tank truck and pulling the washing water solution to a profile control well for profile control.

Three groups of rotary shearing pumps are connected in series in the circulating shearing pool.

The high-pressure pipeline is provided with a flowmeter and a pressure gauge.

A polymer injection well flushing method comprises the following steps:

A. stopping injecting the polymer mother liquor, and injecting the oil field water for 1-2 days;

B. cleaning the polymer;

C. injecting the flowback liquid after well washing into a well washing pool through a high-pressure pipeline for polymer treatment, wherein the pasty liquid after the polymer treatment is used for profile control;

D. after the well washing is finished, oil field water is injected for 1-2 days;

E. the polymer is injected normally.

The step B specifically comprises the following steps:

b1, cleaning residual polymer and attached polymer in the pipe column by circulating flushing of oil field water;

b2, circulation cleaning polymer attached in the well bore and aging polymer near the blast hole.

Step B2 specifically includes:

b21, and a formation micro-leakage well-flushing stage:

controlling the water quantity from the well mouth to be larger than that of the outlet, and adjusting the water quantity of the inlet to be 7m³H, controlling the water quantity at the outlet to be less than 7m³The reverse circulation well washing is carried out for 30min, and after the water quality at the outlet does not contain polymers and silt, the next well washing stage is carried out when the water quantity at the outlet is unchanged and the well washing pressure is constant;

b22, and a stratum micro-jet well-flushing stage:

controlling the water inflow of the well mouth to be less than the water amount of the outlet, and adjusting the water amount of the inlet to be 7m³H, controlling the water outlet quantity to be more than 7m³H; the flow rates at the outlet are respectively 7.5 m, 8.0 m and 8.5m³Flushing each well for 30min at the flow rate of/h, and entering the next well flushing stage when the water quantity at the outlet is unchanged and the well flushing pressure is constant;

b23, balance well washing stage:

at the stage, the outlet water quantity and the stratum discharge quantity are unchanged, the well flushing pressure is prolonged along with the well flushing time, and the well flushing pressure is slowly reduced; when the well washing pressure is reduced to be within 2MPa, the next stage is carried out;

b24, repeating the well washing stage

The steps B22 and B23 are repeated, and the number of the repeated steps depends on the amount of the polymer spitted out from the stratum. When the polymer discharged from the stratum is less and less or even no, and when the water quantity at the outlet and the discharge quantity of the stratum are not changed, the well flushing pressure is prolonged along with the well flushing time, and the well flushing pressure is slowly reduced; when the well washing pressure is reduced to be within 2MPa, the next stage is carried out;

b25, stable well washing stage:

keeping stratum micro-leakage, controlling the water inflow quantity of the wellhead to be larger than the water quantity of the outlet, and adjusting the water quantity of the inlet to be 7m³H, controlling the water quantity at the outlet to be less than 7m³And h, performing reverse circulation well washing for 30min, and finishing well washing after the water at the outlet does not contain polymers and silt.

In the step C, the concrete method for treating the polymer is that the washed polymer clot is precipitated, filtered and crushed in a well washing pool to form pasty liquid, and then the pasty liquid is sent to a water injection well needing to adjust the water absorption profile to be used as a profile control agent.

The technical scheme provided by the invention has the beneficial effects that:

the invention provides a polymer injection well washing device and a polymer injection well washing method. Meanwhile, the washed aged polymer meets the requirements of reinjection or profile control by an economical and efficient physical shearing and crushing method and is used for reinjection or profile control. Therefore, the method can reduce the environmental protection pressure, can be used for profile control, improves the polymer injection effect, realizes the recycling of wastes, and meets the requirements of green, low carbon and sustainable development of oil fields.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a flow chart of a method of a polymer injection well flushing device and a well flushing method according to the present invention;

FIG. 2 is a flow chart of a polymer degradation method of a polymer injection well flushing device and a well flushing method according to the present invention;

FIG. 3 is a schematic structural diagram of a well washing pool of the polymer injection well washing device and the well washing method of the invention;

FIG. 4 is a comparative diagram of the well flushing effect of the polymer injection well flushing device and the well flushing method of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example one

The embodiment provides a polymer injection well washing device, which comprises a well washing pool, wherein the well washing pool is respectively connected with a casing pipe gate and an oil pipe gate through a high-pressure pipeline, as shown in figure 3, the well washing pool comprises a receiving pool 1, a circulating shearing pool 2 and a storage pool 3, the receiving pool 1 is used for receiving eluate at the bottom of a well, a submersible pump 4 is installed in the receiving pool, the submersible pump 4 is used for injecting washing water solution with the eluate at the bottom of the well into the circulating shearing pool 2, a rotary shearing pump 5 and a rod pump 6 are arranged in the circulating shearing pool 2, the rod pump 6 is used for injecting the sheared washing water solution into the storage pool 3 through a pipeline, and a rod pump 7 is arranged in the storage pool and is used for pumping the washing water solution in the storage pool into a sewage tank truck and pulling the washing water solution to a profile control well for profile control.

Three groups of rotary shearing pumps 5 are connected in series in the circulating shearing pool 2.

The polymer injection well washing device of the embodiment consists of a well washing manifold and a polymer processing unit. The well-flushing manifold mainly comprises a tee joint, a quick connector, a high-pressure pipeline, a flowmeter and a pressure gauge. One end of each of the two high-pressure pipelines is connected to the casing gate and the tubing gate, and the other end of each of the two high-pressure pipelines is connected to the wellhead quick connector of the well-flushing tank. Selecting a well washing mode according to the injection condition of the polymer injection well: a backwash well or a forward wash well.

The polymer processing unit, namely a well washing tank, mainly comprises a receiving tank 1, a circulating shearing tank 2 and a storage tank 3. The receiving tank receives mainly the bottom well eluate, and a flow rate of 30m is placed in the tank³A submersible pump 4 for pumping the washed aqueous solution of the washed aged polymer to the circulating shear cell 2 by a transfer pump 4.

After the polymer is sheared for a certain time in the second circulating shearing pool 2 provided with three tandem rotary shearing pumps 5, the aged polymer with the grain diameter smaller than 1-2mm is conveyed to the storage pool 3, namely the third pool by a rod pump 6 in the circulating pool. And when the qualified aged polymer to be treated reaches a certain amount, conveying the polymer to a sewage tank truck through a rod pump 7, and drawing the polymer to a profile control well for profile control.

Example two:

as shown in fig. 1 and 2, the present embodiment provides a polymer injection well flushing method, which includes the following technical means:

before construction: and (4) checking original data information, implementing the water absorption capacity and the starting pressure of each layer, and determining the economic well-flushing displacement range.

1. Determining the liquid volume in the well bore, wherein the depth under the oil pipe is 660 meters generally, the inner diameter of the casing is 124mm, the outer diameter of the oil pipe is 73mm, and the inner diameter of the oil pipe is 62mm,

the first step is as follows: stopping injecting the mother liquid, and injecting the water in the oil field for two days. Thoroughly removing residual polymer in the pipeline and polymer attached on the pipeline;

a second part: cleaning polymer attached to the wellbore and aged polymer near the blasthole. The process is divided into five steps, namely a stratum micro-leakage stage, a stratum micro-spraying stage, a balanced well washing stage, a repeated well washing stage and a stable well washing stage, and water quantity and pressure of an inlet and an outlet in the well washing process need to be measured simultaneously. The flow meter and the pressure gauge on the water supply pipeline at the wellhead are used for monitoring the water supply quantity and the water supply pressure at the inlet and displaying the water quantity at the outlet through the liquid level meter in the pool. The water inflow requirement of the wellhead is not less than 6m³H, generally controlled at 7-8m³And about/h.

(1) In the stratum micro-leakage well-flushing stage, controlling a wellhead) to enable the water inflow amount to be larger than the water outlet amount. Adjusting the water inlet amount to 7m³/hLeft and right, the water quantity of the outlet is controlled to be less than 7m³And h, performing reverse circulation well flushing for about 30min, and entering the next well flushing stage when the outlet water quantity is unchanged and the well flushing pressure is constant after the outlet water quality does not contain polymers and silt.

(2) And in the stratum micro-jet well washing stage, controlling the water inflow amount of a well mouth to be smaller than the water amount of an outlet. Adjusting the water inlet amount to 7m³About/h, the outlet water amount is controlled to be more than 7m³H is used as the reference value. The flow rates at the outlet are 7.5, 8.0 and 8.5m respectively³And each well is washed for about 30min at the flow rate of/h. And determining the well flushing time and the outlet water quantity according to the content of the polymer and the silt in the outlet water. And when the water quantity at the outlet is unchanged and the well washing pressure is constant, entering the next well washing stage.

(3) And (5) balancing a well washing stage. In this stage, the outlet water volume and the stratum discharge volume are not changed. The well washing pressure is slowly reduced along with the prolonging of the well washing time. When the well flushing pressure is reduced to be within 2MPa, the outlet aged polymer is less and less, and the next stage is shifted to when the feeling is not good.

(4) Repeated well flushing stages

The steps B22 and B23 are repeated, and the number of the repeated steps depends on the amount of the polymer spitted out from the stratum. When the polymer discharged from the stratum is less and less or even no, and when the water quantity at the outlet and the discharge quantity of the stratum are not changed, the well flushing pressure is prolonged along with the well flushing time, and the well flushing pressure is slowly reduced; when the well washing pressure is reduced to be within 2MPa, the next stage is carried out;

(5) and (3) stabilizing the well washing stage: maintaining formation microleakage. Controlling the water quantity at the wellhead to be larger than that at the outlet. Adjusting the water inlet amount to 7m³About/h, the outlet water amount is controlled to be less than 7m³And h, performing reverse circulation well washing for about 30min, and finishing well washing after the water at the outlet does not contain polymers and silt.

The third step: and after the well washing is finished, injecting water for 1-2 days, and then recovering normal polymer injection.

The aged polymer treatment flow was as follows:

the process principle is as follows: a closed loop is formed by the polymer injection station, a wellhead, a well washing pool and a reinjection well. The single-injection produced water of the polymer injection station cleans a pipe column, a shaft and a near wellbore area of the high-oil-pressure polymer injection well, flushes out polymer clots, removes blockage and realizes high-efficiency polymer injection by reducing oil pressure. And precipitating, filtering and crushing the washed polymer clot in a well washing pool to form paste liquid, and conveying the paste liquid to a reinjection well for reinjection. The well-flushing pool has a volume of 15m3 and is divided into three parts: the device comprises a flow-back liquid receiving unit (receiving tank 1), a circulating shearing unit (circulating shearing tank 2) and a storage unit (storage tank 3).

As shown in figure 4, the effect before and after the polymer injection well is washed is compared.

After the pipe column is replaced in 7 months in 2018, the pump is started to inject the polymer dry pressure of 13.7MPa, and the oil pressure of 13MPa can only be alternately injected. In 10 months in 2020, the oil pressure and the dry pressure are balanced, the pump is stopped, the single injection is adopted, the water flushing of the pipe column is ineffective, and the well is closed and the injection is stopped.

And in 2021, in 25 days at 4 months, performing polymer injection well immovable pipe column well flushing unblocking construction, in 26 days at 4 months, starting a pump to inject polymer, and completing injection allocation at the oil pressure of 11.6 Mpa.

Change of main index after well flushing

The method is applied to the well washing construction of the four polymer injection wells. After washing, the oil pressure is reduced (the average is reduced by 1-3MPa), the injection amount is completed, the injection energy consumption is reduced, and the oil well liquid level is increased and the daily oil is increased.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.