阅读说明：本技术 一种加快可溶桥塞溶解速率的方法 (Method for accelerating dissolution rate of soluble bridge plug ) 是由 陈强 慕立俊 赵振峰 李宪文 张矿生 唐梅荣 杜现飞 白晓虎 马兵 李晓燕 于 2019-09-11 设计创作，主要内容包括：本发明涉及石油开采领域,具体涉及一种加快可溶桥塞溶解速率的方法,通过金属可溶球为双层结构,包括可溶性金属和填充物,填充物为填充物球体,填充物球体外部包裹可溶性金属形成一个双层的实心球体,可溶球溶解后,填充物会加快可溶桥塞的溶解,且极大加快可溶桥塞溶解速率,从而减少焖井时间,降低压后井筒处理难度,降低压后井筒处理成本,提高井生产时率。(The invention relates to the field of oil exploitation, in particular to a method for accelerating the dissolution rate of a soluble bridge plug.)

1. A method for increasing the rate of dissolution of a soluble bridge plug, comprising: the method for accelerating the dissolution rate of the soluble bridge plug comprises the following steps:

the method comprises the following steps: in the multi-stage fracturing operation process of the horizontal well, after fracturing of a lower perforation (5) stage, blowout is not performed, a cable is used for connecting a perforation gun, a soluble bridge plug putting tool and a soluble bridge plug for pumping, igniting and putting, hole punching (4) operation is performed at the upper stage at the same time, and after the putting of the soluble bridge plug and the perforation continuous operation are successfully completed, a metal soluble ball (7) is put on the soluble bridge plug (5) in a shaft (6) for fracturing operation;

step two: on the basis of the first step, pulling out a cable and a soluble bridge plug putting tool, carrying out normal fracturing construction according to a construction design pump injection program, stopping a pump and closing a well after fracturing operation is finished, and strictly forbidding open flow operation at the moment;

step three: pumping a potassium chloride solution with the volume of 1.2 times and the concentration of 2.0 percent into the corresponding shaft (6) of the last stage in the displacement stage of the last stage of fracturing of the whole well on the basis of the second step;

step four: on the basis of the third step, except the last stage of fracturing section, sequentially repeating the first step and the second step of all other bridge-shooting continuous-working fracturing sections, and repeating the first step, the second step and the third step of the last stage of fracturing until all designed fracturing sections finish fracturing operation, and then closing the well for 24 hours;

step five: on the basis of the fourth step, after the well is closed for 24 hours after the well is pressed, open flow operation is started, and open flow is controlled by adopting a 4mm oil nozzle;

the first blowout amount is 1/3 volume liquid amount corresponding to the volume of the shaft at the depth of the last stage of fracturing section, and the well is closed for 12 hours after blowout;

then carrying out secondary open flow operation, controlling open flow by adopting a 4mm oil nozzle, wherein the open flow is 1/3 volume liquid amount of the volume of the shaft corresponding to the depth of the last stage of fracturing section, and shutting down the well for 12 hours after open flow;

and finally, carrying out tertiary open flow operation, and controlling open flow by adopting a 4mm oil nozzle, wherein the open flow is 1/3 volume liquid amount of the volume of the shaft (6) corresponding to the depth of the last stage of fracturing section, closing the shaft for 12 hours after open flow, the whole shaft is in a closed state, a liquid column in the shaft (6) and the soluble bridge plug (3) have no relative displacement, potassium chloride or sodium chloride particles in the soluble ball for accelerating the dissolution rate of the soluble bridge plug (3) are dissolved in situ, the content of chloride ions around the soluble bridge plug (3) is gradually increased, and the dissolution rate of the soluble bridge plug (3) is accelerated.

2. The method of claim 1, wherein the method comprises the steps of: and after the operation in the fifth step is completely finished, starting to adopt a conventional continuous open flow operation mode until the wellhead condition meets the requirement of cleaning the shaft (6) by the lower oil pipe, and starting to clean the shaft (6), namely washing sand and completing the well.

3. The method of claim 1, wherein the method comprises the steps of: the continuous shut-in time after the pressing is 24 hours, the intermittent shut-in is carried out for 3 times after the continuous shut-in, the total intermittent shut-in time is 36 hours, and the accumulated shut-in time after the pressing is 60 hours.

4. The method of claim 1, wherein the method comprises the steps of: the metal soluble ball (7) in the first step comprises soluble metal (1) and filler (2), the filler (2) is a filler ball, and the soluble metal (1) is wrapped outside the filler ball to form a double-layer solid ball.

5. The method of claim 4, wherein the dissolution rate of the soluble bridge plug is increased by: the radius of the sphere of the filler (2) is smaller than that of the metal soluble sphere (7).

6. The method of claim 4, wherein the dissolution rate of the soluble bridge plug is increased by: the filler (2) is sodium chloride or potassium chloride granules.

7. The method of claim 5, wherein the method further comprises the step of: the filler (2) is potassium chloride.

Technical Field

The invention relates to the field of oil exploitation, in particular to a method for accelerating the dissolution rate of a soluble bridge plug.

Background

The unconventional oil and gas resources in China are rich and mainly distributed in basins such as Ordos, Sichuan, Songliao, Bohai Bay and Quaszec, and exploration evaluation research results show that the total resource amount of the compact oil only reaches 110-135 hundred million tons. With the continuous progress of exploration and development technologies, particularly breakthrough of horizontal well volume fracturing technologies, unconventional oil and gas resource development has been performed pilot tests and made a series of major breakthrough in oil fields such as Changqing oil field, Daqing oil field and Tuha oil field, and the horizontal well soluble bridge plug volume fracturing technology has become the main process technology of unconventional reservoir transformation at present.

Parameters such as the salinity of formation water, the temperature of the formation, the stewing time and the like have obvious influence on the dissolution rate of the soluble bridge plug. In the practical application process of the soluble bridge plug volume fracturing process in a mine field, the soluble bridge plug is insufficiently dissolved due to regional differences of the parameters, so that the working procedures of shaft cleaning, drilling and grinding and the like must be carried out again, the production efficiency of a horizontal well is reduced, the well completion cost is increased, and the application effect of the soluble bridge plug volume fracturing process is greatly influenced. At present, the main methods for accelerating the dissolution of the bridge plug are to prolong the soaking time and adopt a potassium chloride solution in the pumping process of the soluble ball. The disadvantage of prolonging the soaking time is that the well production time rate is influenced; the potassium chloride solution pump ball is adopted to generate potassium chloride solution displacement in the fracturing process, so that the insufficient contact between the potassium chloride solution used as the dissolution promoting solution and the soluble bridge plug is caused to influence the dissolution promoting effect. The soluble bridge plug also consumes a large amount of the chloride ion content of the liquid in the well bore during the dissolution process, and the dissolution rate is reduced under the condition that other parameters are unchanged.

Soluble metal materials adopted by the conventional soluble bridge plug tool are sensitive to formation temperature, formation water mineralization degree, well stewing time and the like. The higher the temperature, the higher the mineralization of the formation water and the longer the soaking time, the better the dissolving effect of the soluble bridge plug. The acceleration of the rate of dissolution of the soluble bridge plug is considered from the three parameters above. Firstly, the difficulty of manual stratum temperature intervention is large; secondly, the soaking time is strictly limited to improve the production efficiency of the well, and the soaking time is not suitable to be too long. Thus, human intervention to the degree of mineralization of the liquid in contact with the soluble bridge plug is considered to increase the rate of dissolution of the soluble bridge plug. In the process of preparing the soluble ball, soluble metal is adopted to wrap sodium chloride or potassium chloride particles, the contained potassium chloride or sodium chloride particles can be dissolved in the formation temperature and the wellbore solution, and a large amount of chloride ions are automatically released in situ, so that the soluble ball has the function of accelerating the dissolution rate of the soluble bridge plug after being dissolved.

Disclosure of Invention

The method overcomes the defects of the prior art, provides a method for accelerating the dissolution rate of the soluble bridge plug, has the characteristic of accelerating the dissolution rate of the soluble bridge plug while meeting the normal construction of the volume fracturing of the soluble bridge plug of the horizontal well, and has the advantages of reducing the operation cost, improving the shaft treatment operation efficiency and improving the production time rate of the well.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

a method for increasing the dissolution rate of a soluble bridge plug, said method comprising the steps of:

the method comprises the following steps: in the multi-stage fracturing operation process of the horizontal well, after fracturing of a lower perforation section, blowout is not performed, a cable is used for connecting a perforating gun, a soluble bridge plug putting tool and a soluble bridge plug for pumping, igniting and putting, meanwhile, the upper-stage perforating operation is performed, and after the putting of the soluble bridge plug and the perforating continuous operation are successfully completed, a metal soluble ball is put on the soluble bridge plug in a shaft for fracturing operation;

step two: on the basis of the first step, pulling out a cable and a soluble bridge plug putting tool, carrying out normal fracturing construction according to a construction design pump injection program, stopping a pump and closing a well after fracturing operation is finished, and strictly forbidding open flow operation at the moment;

step three: pumping a potassium chloride solution with the volume of 1.2 times and the concentration of 2.0 percent of that of the corresponding shaft of the last stage in the displacement stage of the last stage of fracturing of the whole well on the basis of the second step;

step four: on the basis of the third step, except the last stage of fracturing section, sequentially repeating the first step and the second step of all other bridge-shooting continuous-working fracturing sections, and repeating the first step, the second step and the third step of the last stage of fracturing until all designed fracturing sections finish fracturing operation, and then closing the well for 24 hours;

step five: on the basis of the fourth step, after the well is closed for 24 hours after the well is pressed, open flow operation is started, and open flow is controlled by adopting a 4mm oil nozzle;

the first blowout amount is 1/3 volume liquid amount corresponding to the volume of the shaft at the depth of the last stage of fracturing section, and the well is closed for 12 hours after blowout;

then carrying out secondary open flow operation, controlling open flow by adopting a 4mm oil nozzle, wherein the open flow is 1/3 volume liquid amount of the volume of the shaft corresponding to the depth of the last stage of fracturing section, and shutting down the well for 12 hours after open flow;

and finally, carrying out tertiary open flow operation, and controlling open flow by adopting a 4mm oil nozzle, wherein the open flow is 1/3 volume liquid amount corresponding to the volume of the shaft at the depth of the last stage of fracturing section, closing the well for 12 hours after open flow, the whole well is in a well closing state, a liquid column in the shaft and a soluble bridge plug have no relative displacement, potassium chloride or sodium chloride particles in a soluble ball for accelerating the dissolution rate of the soluble bridge plug are dissolved in situ, the content of chloride ions around the soluble bridge plug is gradually increased, and the dissolution rate of the soluble bridge plug is accelerated.

And after the operation in the fifth step is completely finished, starting to adopt a conventional continuous open flow operation mode until the wellhead condition meets the requirement of cleaning the shaft by the lower oil pipe, and starting to perform shaft cleaning operation, namely sand washing and well completion.

The continuous shut-in time after the pressing is 24 hours, the intermittent shut-in is carried out for 3 times after the continuous shut-in, the total intermittent shut-in time is 36 hours, and the accumulated shut-in time after the pressing is 60 hours.

The metal soluble ball in the first step comprises soluble metal and filler, the filler is a filler ball body, and the soluble metal is wrapped outside the filler ball body to form a double-layer solid ball body.

The radius of the filler sphere is smaller than that of the metal soluble sphere.

The filler is sodium chloride or potassium chloride particles.

The filler is potassium chloride.

The invention has the beneficial effects that:

compared with the prior art, the invention comprises the following steps:

1. the well shut-in time is greatly reduced, the soluble ball can greatly accelerate the dissolution rate of the soluble bridge plug, so that the dissolution of solid particle residues of the soluble bridge plug in a shaft is reduced, the treatment complexity of the shaft is reduced, the treatment efficiency of the shaft is increased, the treatment cost of the shaft is saved, and the production time rate of the well is improved.

2. The soluble ball for accelerating the dissolution rate of the soluble bridge plug has the advantages of simple design, easily obtained raw materials, simple preparation process and low cost.

3. After the soluble ball for accelerating the dissolution rate of the soluble bridge plug is dissolved, the solid particle residues in a shaft cannot be increased, the shaft cannot be accumulated with additional solid particles, and stratum pollution cannot be caused.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic cross-sectional view of a metal soluble sphere of the present invention.

Fig. 2 is a schematic diagram of the position structure of the metal soluble ball in the well bore.

In the figure: 1-soluble metal, 2-filler, 3-soluble bridge plug, 4-upper perforation segment, 5-lower perforation segment, 6-pitshaft and 7-metal soluble ball.

Detailed Description