阅读说明：本技术 一种应用暂堵剂判断二氧化碳地质封存泄漏点的方法 (Method for judging carbon dioxide geological sequestration leakage point by using temporary plugging agent ) 是由 张钰园 温庆志 张东晓 杨富康 于 2020-06-08 设计创作，主要内容包括：本发明提供了一种应用暂堵剂判断二氧化碳地质封存泄漏点的方法,本发明主要通过向初步定位的CO<Sub>2</Sub>泄漏点中注入暂堵剂进行暂堵,监测注入暂堵剂前后泄漏点的监测指标,如果暂堵后相对于暂堵前的指标变化,说明暂堵位置是泄漏点,如果监测指标没有变化,说明暂堵位置不是泄漏点,重新定位CO<Sub>2</Sub>泄漏；本发明可以有效的提高封堵效率与准确性,防止错误的堵塞有生产价值的油气孔道；若封堵无效,暂堵剂会在一段时间后自行降解,不会对地层造成伤害。(The invention provides a method for judging a carbon dioxide geological sealing leakage point by using a temporary plugging agent, which mainly comprises the step of determining the preliminarily positioned CO 2 Injecting a temporary plugging agent into the leakage point for temporary plugging, monitoring the monitoring indexes of the leakage point before and after the temporary plugging agent is injected, if the indexes before temporary plugging are changed relative to the indexes before temporary plugging after temporary plugging, indicating that the temporary plugging position is the leakage point, if the monitoring indexes are not changed, indicating that the temporary plugging position is not the leakage point, repositioning CO 2 Leakage; the invention can effectively improve the plugging efficiency and accuracy and prevent the mistaken plugging of oil-gas pore channels with production value; if the plugging is ineffective, the temporary plugging agent can be automatically degraded after a period of time, and the stratum cannot be damaged.)

1. A method for judging a carbon dioxide geological sequestration leakage point by using a temporary plugging agent comprises the following steps:

1) to preliminary location of CO₂Injecting temporary plugging agent into the leakage point for temporary plugging;

2) monitoring the monitoring indexes of the leakage points before and after the temporary plugging agent is injected in the step 1), wherein the monitoring indexes change relative to the monitoring indexes before the temporary plugging after the temporary plugging, and the temporary plugging position is the leakage point; after temporary plugging, the monitoring index is unchanged relative to that before temporary plugging, which indicates that the position of temporary plugging is not a leakage point, and the CO is repositioned₂And (4) leakage points.

2. The method of claim 1, wherein the step 1) of preliminarily locating the CO₂The monitoring technology of the leakage point is one or more than two of seismic imaging technology, pressure monitoring technology and geochemical parameter monitoring technology.

3. The method according to claim 1, wherein the CO in the step 1)₂The leak point of (a) is a abandoned well or a producing well.

4. The method according to claim 1, wherein the monitoring index in step 2) is CO₂And (4) concentration.

5. The method of any one of claims 1 to 4 applied to geological sequestration of carbon dioxide.

6. The method of claim 5 for geological sequestration of carbon dioxide, wherein CO is produced in abandoned or recovered wells₂Sealing and storing.

Technical Field

The invention relates to a method for judging a carbon dioxide geological sequestration leakage point by using a temporary plugging agent, belonging to the field of carbon dioxide geological sequestration.

Background

Over the past century, atmospheric carbon dioxide levels have risen by over 39%, with global average air temperatures rising by about 0.8 ℃. Global concern over greenhouse gas emissions has motivated the capture and sequestration of carbon dioxide in geological reservoirs: (CCUS) has been of considerable research interest. The carbon dioxide sequestration sites are mainly abandoned or depleted oil and gas reservoirs, coal beds with deeper depths or smaller thicknesses and undevelopable deep brine layers. In the actual process of carbon dioxide sequestration, a widely existing problem is that carbon dioxide may leak from underground storage points to the near surface and then enter the atmosphere, exacerbating the greenhouse effect. CO according to the 2006 IPCC national greenhouse gas List guide, CO₂There are mainly 4 possible ways in which leaks may occur during geological sequestration: (1) through reservoir cover rock leakage, CO2 breaks through the restriction of the capillary force of the cover rock and leaks through the pores of the low-permeability shale, gypsum and other cover rock; (2) through fracture networks and fault leaks in geological formations, if the cap layer is dense, faults or fractures present in the formation may affect the integrity of the cap layer resulting in CO₂Leakage of (2); (3) disposal of leaks by unclosing producing, abandoned and injection wells in oil fields, abandoned wellbores are considered to be a more hazardous leak path, and plugging is poor or due to corrosion of cement and casing, CO is enhanced₂The rate of leakage; (4) after injection, the original regional underground water power system is changed, leakage is caused through the hydrokinetic system of the reservoir and the surrounding rock, and the leakage modes mainly include lateral leakage, loss through a cover layer, leakage through a shaft and the like. Where plugged and abandoned wells are the channels with the greatest risk of leakage, CO₂The leakage path is schematically shown in FIG. 1.

Some researchers are considering CO₂On the basis of geological storage safety, the method proposes that the geochemical indexes related to carbon dioxide leakage by taking atmosphere, soil, water and stratum as objects are monitored for CO₂And (4) carrying out pre-perfusion background value monitoring, perfusion period control monitoring and post-closure monitoring on geological storage. At present, CO does not deal with₂A mature system for sealing leakage with only a small amount of CO₂The way of dealing with the leakage problem during the sealing process was studied. Chinese patent document CN104726079A (application No. 201510039361.1) discloses a CO₂The gas-sensitive chemical plugging agent comprises the following components in percentage by mass: partially hydrolyzed polyacrylamide with mass content of 0.1-1 percent; 0.3-1% of phenolic aldehyde crosslinking agent relative to the mass ratio of the partially hydrolyzed polyacrylamide aqueous solution; 0.01-0.1% of montmorillonite; 0.1-0.3% thiourea deoxidant and 0.01-0.5% alkali; the rest is water. CO encountering leakage₂Gelling, precipitation or curing reactions occur during the plugging of the leakage paths, but the plugs formed in this way are permanent and have the problem that the plugging location is uncertain, which can lead to irreversible large losses if a plugging location error occurs during the plugging process. Zhang Yuyuan et al, in Energy Science and Engineering journal, A novel targeted plugging and applying gel used as a differentiating agent in fracturing. The temporary plugging agent combines the advantages of a viscous fluid diverting agent and a solid particle diverting agent, the viscous fluid diverting agent can enter deep parts of narrow cracks, and the plugging effect is good; the solid particle diverting agent has higher strength and higher bearing capacity. The high-strength degradable plugging agent is composed of two water-soluble particles and a high-strength degradable fiber, wherein the two particles are respectively dissolved to form viscous fluid, and a certain amount of fiber is carried to be injected into the underground in a fluid form, so that the viscous fluid can enter deep parts of fine cracks, and the viscous fluid is converted into solid plugging with certain strength which is adaptive to the shapes of the cracks after a period of time. Compared with the common viscous fluid diverting agent, the temporary plugging agent has higher strength and stronger pressure bearing capacity; compared with the common solid particle diverting agent, the diverting agent has the advantages of adapting to the shape and the size of the crack.

Current research on geological sequestration is mainly focused on CO₂In the sequestration and monitoring technologies of, and in CO₂The gas leakage in the sealing process is a common problem, normal oil and gas channels can be blocked due to the wrong sealing position by using the common sealing agent for sealing, and the stratum can be irreversibly damaged due to the permanence and the persistence of sealing by using the common sealing agent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for judging a carbon dioxide geological sealing leakage point by using a temporary plugging agent.

The invention selects a temporary plugging agent proposed by Zhang Yuyuan et al in 'A novel targeted plugging and fragmentation-adaptive gel used as a differentiating agent in fragmentation', summarizes the characteristics of the temporary plugging agent as follows: (1) self-adaptability: the diverter system is injected in a fluid form and can enter fractures of any shape and size to form plugging with certain strength; (2) plugging at fixed points: the time for converting the steering system from fluid to solid can be controlled by controlling the adding concentration and proportion of each component in the steering agent system, so that the timed positioning plugging is realized; (3) environmental protection and no toxicity: the components in the diverter system and degradation products thereof are nontoxic and harmless, so that the pollution to reservoir and underground water can be reduced; (4) self-cleaning: the degradation product of the diverting agent system is acidic, and can dissolve residual filter cakes at the bottom of the well, thereby realizing self-cleaning at the bottom of the well. The temporary plugging agent can realize the positioning plugging of cracks with various shapes and sizes by adjusting the parameters such as the concentration, the proportion and the like of each component of the temporary plugging agent, and can degrade automatically within a period of time.

The invention utilizes the temporary plugging agent to treat CO₂And (3) temporarily blocking the leakage position, monitoring related indexes at nearby monitoring points, and determining an accurate leakage point according to the change of the indexes of the monitoring points before and after temporary blocking so as to perform directional blocking.

The technical scheme involved in the invention is as follows;

the invention provides a method for judging a carbon dioxide geological sealing leakage point by using a temporary plugging agent, which comprises the following steps:

1) to preliminary location of CO₂Injecting temporary plugging agent into the leakage point for temporary plugging;

2) monitoring the monitoring indexes of the leakage points before and after the temporary plugging agent is injected in the step 1), wherein the monitoring indexes change relative to the monitoring indexes before the temporary plugging after the temporary plugging, and the temporary plugging position is the leakage point; after temporary plugging, the monitoring index is unchanged relative to that before temporary plugging, which indicates that the position of temporary plugging is not a leakage point, and CO is continuously repositioned₂And (4) leakage points.

The temporary plugging agent has the characteristic of self-degradation within a certain time.

Preferably according to the invention, step 1) is preliminary determinationPosition CO₂The monitoring technology of the leakage point is one or more than two of seismic imaging technology, pressure monitoring technology and geochemical parameter monitoring technology.

Preferably, according to the invention, the leak in step 1) is a abandoned well or a producing well.

According to the invention, preferably: the monitoring index in the step 2) is CO₂And (4) concentration.

The method is applied to geological storage of carbon dioxide.

Preferably, the method is applied to CO in abandoned wells or produced wells₂Sealing and storing.

The temporary plugging agent related in the technical scheme of the invention is 'A novel targeted plugging and profiling-adaptive gel used as a differentiating agent in profiling', and the authors are Yuyan Zhang, Qingzhi Wen, Dongxiao Zhang, Energy Science and Engineering, and the temporary plugging agent is disclosed in 12 months 12 in 2019 for the first time.

The invention relates to the technical scheme and has the beneficial effects

The research provides a method for judging carbon dioxide geological sealing leakage points by using a temporary plugging agent, the temporary plugging agent is used for temporarily plugging positions predicted to be possible to leak, the temporary plugging agent can control the positions for forming plugging by adjusting the concentration and the proportion of components, and is injected in a liquid form, so that solids with certain strength are gradually generated, and the method can adapt to plugging points with different shapes and sizes; CO at the site while injecting temporary plugging agent₂Monitoring the concentration, verifying whether the plugging is effective according to a monitoring result, if the plugging is effective, indicating the accuracy of the plugging position, and permanently plugging the position by using a permanent plugging material, so that the plugging efficiency and accuracy can be effectively improved, and the oil and gas pore passages with production values can be prevented from being blocked by mistake; if the plugging is ineffective, the temporary plugging agent can be automatically degraded after a period of time, and the stratum cannot be damaged.

Drawings

FIG. 1: CO2₂Schematic of leakage pathway

In the figure, a, leakage of reservoir cap rock, b, leakage of fault in geological structure, c, leakage of a mining well and a abandoned well;

FIG. 2: CO determination using temporary plugging agents₂Flow diagram of method for sealing leakage point

FIG. 3: shaft casing leakage temporary plugging schematic diagram

FIG. 4: temporary plugging schematic diagram for leakage of well cementation cement sheath

FIG. 5: temporary capping leakage

FIG. 6: fault leakage temporary plugging diagram

The specific implementation mode is as follows:

the technical solutions according to the present invention are further illustrated by the following examples, but the scope of protection is not limited thereto.

The invention uses the temporary plugging agent to judge CO₂The process schematic of the leak point containment method is shown in FIG. 2.

Sources of materials