阅读说明：本技术 一种抗碱水泥浆堵漏方法 (Alkali-resistant cement slurry plugging method ) 是由 李山岭 吴巴特尔 杨帆 王上行 李守刚 刘二明 李华伟 于 2021-05-27 设计创作，主要内容包括：本发明公开了一种抗碱水泥浆堵漏方法,包括以下步骤；步骤一、首先分析井内涌水化学成分,依据其成分,利用井下涌出的碱卤,室内调制堵漏抗碱水泥浆配方并通过测试,后通过计算需要的堵漏抗碱水泥浆量,现场储存一定量的井下碱卤,以备调制抗碱水泥浆所需,观测涌水静压力,后测量井内泥浆比重,计算涌水地层压力,推算配重泥浆比重,依据井深和井径。本发明不仅为冒水治涌提供了方法,而且彻底解决了资源开采受限问题,改变了天然碱开采压裂水溶采矿工艺的局限性,保证了水泥浆自身的纯净性,增加了水泥浆胶结强度,增强堵漏水泥浆凝结后的刚性,保证成井率,也减少由此带来的环保压力。(The invention discloses an alkali-resistant cement slurry plugging method, which comprises the following steps of; firstly, analyzing chemical components of water burst in a well, utilizing alkali brine gushed out from the well according to the components, preparing a formula of the leakage-blocking alkali-resistant cement slurry indoors, testing, calculating the required amount of the leakage-blocking alkali-resistant cement slurry, storing a certain amount of alkali brine in the well on site for preparing the alkali-resistant cement slurry, observing the water burst static pressure, measuring the specific gravity of the slurry in the well, calculating the pressure of a water burst stratum, calculating the specific gravity of the weighted slurry, and calculating the specific gravity of the weighted slurry according to the depth and the diameter of the well. The invention not only provides a method for controlling the gushing of the water bleeding, but also thoroughly solves the problem of limited resource exploitation, changes the limitation of the natural alkali exploitation fracturing water-soluble mining process, ensures the purity of the cement paste, increases the cementing strength of the cement paste, enhances the rigidity of the coagulated plugging cement paste, ensures the well forming rate, and reduces the environmental protection pressure caused by the method.)

1. An alkali-resistant cement slurry plugging method is characterized in that: comprises the following steps; firstly, analyzing chemical components of water burst in a well, utilizing alkali brine gushed out from the well according to the components, preparing a formula of the leakage-stopping alkali-resistant cement slurry indoors, testing, calculating the required amount of the leakage-stopping alkali-resistant cement slurry, storing a certain amount of alkali brine in the well on site to prepare for the requirement of preparing the alkali-resistant cement slurry, observing the water burst static pressure, measuring the specific gravity of the slurry in the well, calculating the pressure of a water burst stratum, calculating the specific gravity of the weight-balancing slurry, calculating the volume of the weight-balancing slurry according to the depth and the diameter of the well, preparing the slurry, injecting the slurry into the well, establishing circulation when the pressure in the well is balanced, keeping the activity of the slurry in the well, inserting a pipe string to about 50 meters above a leakage loss layer, injecting the leakage-stopping cement slurry, completing well injection, lifting the pipe string after slurry replacement, then closing the well and waiting for coagulation, detecting plugs and cleaning after 72 hours, and checking the quality of the leakage stoppage; step two, the viscosity of the proportioning slurry is high, the proportioning slurry is not easy to lose water, the specific gravity is uniform, the specific gravity is unchanged after circulation is established, the pressure in the well is balanced, and unbalance is not easy to occur; step three, the pipe string can be lifted completely or only 500 meters, so that the distance between the liquid level of the plugging cement slurry and the bottom end of the pipe string is 300 meters, and the standard of not inserting a flagpole is met; and step four, finally, sealing the well and waiting for setting, wherein the specific gravity of the alkali-resistant cement slurry is generally far greater than that of the proportioning slurry, after the materials are injected, the pressure in the whole shaft is greater than the pressure of the stratum, the whole liquid column is in a slow descending process, the alkali-resistant cement slurry can slowly enter a preset leakage layer along with the action of gravity, the operation is slow due to no external force, the loss of the cement slurry is reduced, the wellhead is sealed to form a vacuum column along with the descending of the liquid column, when the vacuum column reaches a certain length, the bottom hole pressure reaches balance, and at the moment, the pressure in the well is reduced along with the solidification of the alkali-resistant cement slurry to form an underbalanced state, so that the cement at the lower part has a certain adsorption effect, the loss is avoided, and the leakage blocking effect is improved to the maximum extent.

2. The alkali-resistant cement slurry plugging method according to claim 1, characterized in that: the commonly used retarder in the preparation process of the plugging alkali-resistant cement paste is mostly organic acid retarder or polymer retarder.

Technical Field

The invention belongs to the technical field of natural alkali drilling casing well cementation, and particularly relates to an alkali-resistant cement slurry plugging method.

Background

At present, for mining of ore beds of deeply buried soluble salts (trona, mirabilite, rock salt and the like), a drilling water-soluble mining method is adopted at home and abroad, namely, drilling a drill bit to a target layer through a drill rod by using drilling equipment, then putting a production casing pipe and a central pipe into a well to complete the construction process of a new well, injecting water into the central pipe or the casing pipe, injecting an injection agent into an underground resource layer, dissolving resources, and enabling a dissolved solution to become original brine to return to the earth surface, namely, completing a mining process. However, with the continuous deep mining, a large amount of injection agent is injected into the ground under high pressure, so that the original stable formation stress state and the underground stress balance are broken, the formations filled with high-pressure water become hidden troubles of future mining areas, once the blocks and the layers are drilled, a large amount of alkali-containing brine water gushes (or leaks) phenomenon occurs, and the gushing water layers need to be blocked in order to form a well.

The main components of the natural alkali brine are Na2CO3 and NaHCO3, and the substances have stronger coagulation promoting effect on a cement slurry system due to the existence of ionizable CO 32-and HCO 3-; the alkali halide is electrolyte, the cement paste is colloid, and the colloid is rapidly precipitated when meeting the electrolyte. The natural alkali halide enters a conventional cement paste system to promote the cement paste to flocculate, and the injected cement paste has no strength after solidification, so that the plugging cannot be successful.

In order to solve the contradiction, from the viewpoint of influence of alkali halide on cement paste, alkali halide emitted from the stratum is used for proportioning the cement paste, and the problem of alkali resistance and stability of the cement paste is used for offsetting or avoiding the problem, so that solidification of the cement paste is effectively guaranteed.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the alkali-resistant cement paste plugging method which ensures the purity of cement paste, increases the cementing strength of the cement paste, enhances the rigidity of the plugging cement paste after being coagulated and ensures the well forming rate.

In order to achieve the design purpose, the technical scheme adopted by the invention is as follows: an alkali-resistant cement slurry plugging method comprises the following steps:

firstly, analyzing chemical components of water burst in a well, utilizing alkali brine gushed out from the well according to the components, preparing a formula of the leakage-stopping alkali-resistant cement slurry indoors, testing, calculating the required amount of the leakage-stopping alkali-resistant cement slurry, storing a certain amount of alkali brine in the well on site to prepare for the requirement of preparing the alkali-resistant cement slurry, observing the water burst static pressure, measuring the specific gravity of the slurry in the well, calculating the pressure of a water burst stratum, calculating the specific gravity of the weight-balancing slurry, calculating the volume of the weight-balancing slurry according to the depth and the diameter of the well, preparing the slurry, injecting the slurry into the well, establishing circulation when the pressure in the well is balanced, keeping the activity of the slurry in the well, inserting a pipe string to about 50 meters above a leakage loss layer, injecting the leakage-stopping cement slurry, completing well injection, lifting the pipe string after slurry replacement, then closing the well and waiting for coagulation, detecting plugs and cleaning after 72 hours, and checking the quality of the leakage stoppage;

step two, the viscosity of the proportioning slurry is high, the proportioning slurry is not easy to lose water, the specific gravity is uniform, the specific gravity is unchanged after circulation is established, the pressure in the well is balanced, and unbalance is not easy to occur;

step three, the pipe string can be lifted completely or only 500 meters, so that the distance between the liquid level of the plugging cement slurry and the bottom end of the pipe string is 300 meters, and the standard of not inserting a flagpole is met;

and step four, finally, sealing the well and waiting for setting, wherein the specific gravity of the alkali-resistant cement slurry is generally far greater than that of the proportioning slurry, after the materials are injected, the pressure in the whole shaft is greater than the pressure of the stratum, the whole liquid column is in a slow descending process, the alkali-resistant cement slurry can slowly enter a preset leakage layer along with the action of gravity, the operation is slow due to no external force, the loss of the cement slurry is reduced, the wellhead is sealed to form a vacuum column along with the descending of the liquid column, when the vacuum column reaches a certain length, the bottom hole pressure reaches balance, and at the moment, the pressure in the well is reduced along with the solidification of the alkali-resistant cement slurry to form an underbalanced state, so that the cement at the lower part has a certain adsorption effect, the loss is avoided, and the leakage blocking effect is improved to the maximum extent.

The commonly used retarder in the preparation process of the plugging alkali-resistant cement paste is mostly organic acid retarder or polymer retarder, and the following cement paste performance table is prepared by using alkali water with certain concentration at 70 ℃ (50% alkali water):

the invention has the beneficial effects that: the commonly used retarder in the preparation process of the plugging alkali-resistant cement paste is mostly organic acid retarder or polymer retarder, and the retarder is generally provided with H⁺，H⁺Will react with CO in the alkaline water₃ ^2-H in the acidic retarder reacts to generate water and carbon dioxide gas in the process of preparing medicine water⁺And CO in alkaline water₃ ^2-Consumption of the retarder is reduced, and on one hand, the retarding effect of the retarder is reduced; on the other hand, CO in the medicine water₃ ^2-The ion balance between the ion source and underground alkaline water cannot be achieved; the invention can prepare the cement paste by using alkali-containing brine which overflows from a well according to the underground condition, and uses starch macromolecular inert materials to shield the influence of related ions on cement under an alkaline environment, so that the formula cement paste has alkali resistance, thereby achieving the aim of cement paste solidification. The invention not only provides a method for controlling the gushing of the water bleeding, but also thoroughly solves the problem of limited resource exploitation, changes the limitation of the natural alkali exploitation fracturing water-soluble mining process, ensures the purity of the cement paste, increases the cementing strength of the cement paste, enhances the rigidity of the coagulated plugging cement paste, ensures the well forming rate, and reduces the environmental-friendly pressure caused by the methodForce.

Drawings

FIG. 1 is a schematic representation of the cured hardness of a 70 deg.C (50% alkaline water) cement slurry of the present invention as a function of time.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. As shown in fig. 1: an alkali-resistant cement slurry plugging method comprises the following steps:

firstly, analyzing chemical components of water burst in a well, utilizing alkali brine gushed out from the well according to the components, preparing a formula of the leakage-stopping alkali-resistant cement slurry indoors, testing, calculating the required amount of the leakage-stopping alkali-resistant cement slurry, storing a certain amount of alkali brine in the well on site to prepare for the requirement of preparing the alkali-resistant cement slurry, observing the water burst static pressure, measuring the specific gravity of the slurry in the well, calculating the pressure of a water burst stratum, calculating the specific gravity of the weight-balancing slurry, calculating the volume of the weight-balancing slurry according to the depth and the diameter of the well, preparing the slurry, injecting the slurry into the well, establishing circulation when the pressure in the well is balanced, keeping the activity of the slurry in the well, inserting a pipe string to about 50 meters above a leakage loss layer, injecting the leakage-stopping cement slurry, completing well injection, lifting the pipe string after slurry replacement, then closing the well and waiting for coagulation, detecting plugs and cleaning after 72 hours, and checking the quality of the leakage stoppage;

step two, the viscosity of the proportioning slurry is high, the proportioning slurry is not easy to lose water, the specific gravity is uniform, the specific gravity is unchanged after circulation is established, the pressure in the well is balanced, and unbalance is not easy to occur;

step three, the pipe string can be lifted completely or only 500 meters, so that the distance between the liquid level of the plugging cement slurry and the bottom end of the pipe string is 300 meters, and the standard of not inserting a flagpole is met;

and step four, finally, sealing the well and waiting for setting, wherein the specific gravity of the alkali-resistant cement slurry is generally far greater than that of the proportioning slurry, after the materials are injected, the pressure in the whole shaft is greater than the pressure of the stratum, the whole liquid column is in a slow descending process, the alkali-resistant cement slurry can slowly enter a preset leakage layer along with the action of gravity, the operation is slow due to no external force, the loss of the cement slurry is reduced, the wellhead is sealed to form a vacuum column along with the descending of the liquid column, when the vacuum column reaches a certain length, the bottom hole pressure reaches balance, and at the moment, the pressure in the well is reduced along with the solidification of the alkali-resistant cement slurry to form an underbalanced state, so that the cement at the lower part has a certain adsorption effect, the loss is avoided, and the leakage blocking effect is improved to the maximum extent.

Example 1:

(1) after a water inrush layer is found, recording the position of the water inrush layer in detail, observing the water inrush amount, estimating the size of a possible dissolution cavity or crack, closing a wellhead, installing a pressure gauge, observing the static pressure of the wellhead, measuring the specific gravity of the slurry in the well, calculating the pressure of the water inrush layer, proportioning the specific gravity of the pressure-weighted slurry according to the specific gravity, generally speaking, the specific gravity of the actual proportioning pressure-weighted slurry is slightly higher than the calculated value, the increment is about 0.1-0.3 g/l, calculating the volume of the slurry in the shaft, taking the volume as the volume of the proportioning pressure-weighted slurry, and generally increasing the surplus by 20%;

(2) after the balance weight mud is modulated, the mud can be injected into the shaft, the mud can be directly injected from the wellhead, or can be injected to a certain depth through a pipe insertion, and finally, the mud at the wellhead does not upwelle any more, so that the balance is achieved; the plugging pipe string is put to the 300 m position on the upper part of the leakage layer to establish slurry circulation, the slurry activity is maintained after 20 minutes of circulation, the rear pipe string continues to go down to the 50 m position on the leakage layer, alkali-resistant cement slurry starts to be injected, and the injection amount of the alkali-resistant cement slurry is based on the estimated thickness and the plugging radius of the leakage layer and is preferably 30 square;

(3) replacing the alkali-resistant cement slurry after the injection of the alkali-resistant cement slurry is finished, preventing the inner of the pipe string from being blocked, lifting the pipe string 500 meters or completely out, quickly injecting the slurry replacing the volume of the pipe string, sealing the well, waiting for setting, slowly descending the liquid column in the well due to the high specific gravity of the leaking stoppage cement slurry, sealing the upper wellhead to form partial vacuum, and gradually forming an underbalance state;

(4) and opening the wellhead after waiting for solidification for 72 hours, taking out the residual pipe string, probing the plug and sweeping the plug, and checking the plugging quality.