阅读说明：本技术 一种通过投球暂堵促进多簇裂缝均衡扩展的方法 (Method for promoting balanced expansion of multiple clusters of cracks through ball throwing and temporary plugging ) 是由 郭洪金 肖佳林 刘炜 李奎东 张炜 明月 王升 于 2020-05-20 设计创作，主要内容包括：本发明公开了一种通过投球暂堵促进多簇裂缝均衡扩展的方法,包括如下步骤：将一个压裂段的整个压裂施工过程分为N级,实施第一级压裂：向井筒内注入能促进裂缝起裂、扩展的不同类型组合的压裂液；实施第二级压裂：继续注入压裂液,并向井筒内投入可降解型暂堵球,用于临时封堵射孔簇孔眼,限制优势水力裂缝的扩展,继续注入压裂液促进非优势裂缝的扩展；后续几级压裂施工过程和第二级类似,直至完成该压裂段的施工；按照上述过程完成后续其它压裂段的施工,最终实现对整个水平段储层的均衡压裂改造。本发明可有效改善多簇裂缝的不均衡扩展现象,增大储层改造体积,提高油气采收率,广泛适用于多种储层类型。(The invention discloses a method for promoting balanced expansion of multiple clusters of cracks through ball throwing and temporary plugging, which comprises the following steps: dividing the whole fracturing construction process of a fracturing section into N grades, implementing first-stage fracturing: injecting fracturing fluid which can promote the initiation and the expansion of cracks into the shaft and are combined in different types; and (3) implementing a second stage of fracturing: continuously injecting fracturing fluid, and putting a degradable temporary plugging ball into the shaft for temporarily plugging perforation cluster holes to limit the expansion of the dominant hydraulic fracture, and continuously injecting the fracturing fluid to promote the expansion of the non-dominant fracture; the subsequent construction process of the fracturing of several stages is similar to that of the second stage until the construction of the fracturing section is completed; and (4) completing the construction of other follow-up fracturing sections according to the process, and finally realizing the balanced fracturing transformation of the reservoir of the whole horizontal section. The method can effectively improve the unbalanced expansion phenomenon of multiple clusters of cracks, increase the reservoir reconstruction volume, improve the oil and gas recovery ratio, and is widely suitable for various reservoir types.)

1. A method for promoting balanced expansion of multiple clusters of cracks through ball injection and temporary plugging is characterized by comprising the following steps:

dividing the whole fracturing construction process of one fracturing section into N stages, wherein N is more than or equal to 2, and the specific stages can be dynamically adjusted according to site geology, engineering conditions and fracturing construction effects;

performing a first stage of fracturing: injecting fracturing fluid which can promote the initiation and the expansion of cracks into the shaft and are combined in different types;

and (3) implementing a second stage of fracturing: continuously injecting fracturing fluid, and putting a degradable temporary plugging ball into the shaft for temporarily plugging perforation cluster holes to limit the expansion of the dominant hydraulic fracture, and continuously injecting the fracturing fluid to promote the expansion of the non-dominant fracture;

the subsequent construction process of the fracturing of several stages is similar to that of the second stage until the construction of the fracturing section is completed;

and (4) completing the construction of other follow-up fracturing sections according to the process, and finally realizing the balanced fracturing transformation of the reservoir of the whole horizontal section.

2. The method for promoting the balanced propagation of multiple clusters of fractures through ball dropping and temporary plugging according to claim 1, wherein the specific process for implementing the first stage of fracturing is as follows: firstly, injecting a certain volume of acid liquor into a shaft; then injecting a certain volume of glue solution into the shaft; and further injecting water reducing water into the shaft, and then adding proppants with different particle sizes.

3. The method for promoting the balanced propagation of multiple fractures through ball-dropping temporary plugging according to claim 2, wherein the volume of the injected acid solution is 10-30m³The volume of the injected glue solution is 80-200m³The volume of injected water reducing is 800-³The particle size of the proppant is 106-600 um.

4. The method for promoting the balanced propagation of multiple clusters of fractures through ball injection temporary plugging according to claim 3, wherein the particle size of the added proppant is added in batches from small to large.

5. The method for promoting the balanced expansion of the multiple fractures by ball dropping and temporary plugging according to claim 1 or 2, wherein in the second stage of fracturing construction, acid liquor and glue liquor are not injected into the shaft, but the temporary plugging ball is started after the water reducing water is directly injected.

6. The method for promoting the balanced expansion of the multiple clusters of cracks through temporary ball injection plugging as claimed in claim 5, wherein after the temporary ball injection plugging reaches the position of the perforation and the ground construction pressure rises stably, the method indicates that the ball injection effectively plugs the perforation with sufficient liquid, and the propping agents with different particle sizes are continuously added.

7. The method for promoting the balanced propagation of multiple fractures through temporary plugging by pitching as claimed in claim 5, wherein the volume of injected water-reducing water is 800-1000m³。

Technical Field

The invention relates to the field of research of oil and gas reservoir development technologies, in particular to a method for promoting balanced expansion of multiple clusters of fractures through ball injection and temporary plugging.

Background

In recent years, unconventional natural gas resources such as shale gas, tight sandstone gas and the like gradually enter a large-scale commercial development stage, and because reservoirs of the type are tight and low in permeability, oil and gas cannot spontaneously flow into a shaft from rock pores, the current horizontal drilling and segmented multi-cluster fracturing technology is the most effective development mode.

Horizontal drilling, i.e., the trajectory of a wellbore passing horizontally inside a reservoir, maximizes the contact area of the wellbore with the reservoir relative to a vertical well.

The staged multi-cluster fracturing technology is a reservoir stratum modification technology based on a horizontal well. The method comprises the following steps that a horizontal well section is divided into a plurality of sections, a plurality of perforation positions are set in each section, a well wall is shot through at the perforation positions through perforating bullets, and a perforation cluster is formed to serve as an initial fracture initiation position; injecting fracturing fluid into the ground through a shaft, performing packing fracturing on each section one by one, continuously increasing the pressure of the shaft in each section along with the continuous injection of the fracturing fluid, finally initiating hydraulic fractures to initiate fracture initiation and expansion at a plurality of perforation clusters in each section to form a plurality of artificial fractures, mixing a propping agent into the fracturing fluid during the process, conveying the propping agent to a reservoir stratum, and keeping the fractures open for a long time after the propping agent enters the fractures; after all the sections are fractured, dozens or even hundreds of artificial hydraulic fractures are formed in the reservoir, the permeability of the reservoir is greatly increased, and oil gas in the compact pores can be smoothly extracted, as shown in figure 1.

At present, the traditional segmented multi-cluster fracturing technology has some defects, the balanced expansion of multi-cluster fractures cannot be ensured, and the range and the effect of reservoir transformation are greatly reduced. The concrete expression is as follows: in one fracturing section, although the plurality of perforation clusters can form the initiation and expansion of hydraulic fractures, only a small part of the hydraulic fractures can fully extend to the deep part of a reservoir, other fractures stop after the hydraulic fractures are expanded by a small distance, similar situations can occur in each fracturing section, and finally, a considerable proportion of artificial hydraulic fractures are not fully extended, so that the actual transformation area of the reservoir is small, as shown in fig. 2. The reasons for this are manifold, such as heterogeneity of reservoir, difference of liquid inlet amount at each perforation cluster position, and competitive inhibition during multi-cluster fracture propagation.

At present, no effective method for ensuring the balanced propagation and extension of multiple clusters of cracks exists. The method can effectively improve the non-uniform expansion of the multi-cluster cracks and enlarge the reservoir reconstruction area without generating any adverse effect on the premise of keeping the existing hydraulic fracturing construction process basically unchanged.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for promoting the balanced expansion of a plurality of clusters of cracks through ball throwing and temporary plugging, which can enlarge a reservoir transformation area and effectively improve the unconventional oil and gas recovery ratio, aiming at the defects in the prior art.

The technical scheme adopted by the invention is as follows: a method for promoting balanced expansion of multiple clusters of cracks through ball injection and temporary plugging is characterized by comprising the following steps:

dividing the whole fracturing construction process of one fracturing section into N stages, wherein N is more than or equal to 2, and the specific stages can be dynamically adjusted according to site geology, engineering conditions and fracturing construction effects;

performing a first stage of fracturing: injecting fracturing fluid which can promote the initiation and the expansion of cracks into the shaft and are combined in different types;

and (3) implementing a second stage of fracturing: continuously injecting fracturing fluid, and putting a degradable temporary plugging ball into the shaft for temporarily plugging perforation cluster holes to limit the expansion of the dominant hydraulic fracture, and continuously injecting the fracturing fluid to promote the expansion of the non-dominant fracture;

the subsequent construction process of the fracturing of several stages is similar to that of the second stage until the construction of the fracturing section is completed;

and (4) completing the construction of other follow-up fracturing sections according to the process, and finally realizing the balanced fracturing transformation of the reservoir of the whole horizontal section.

According to the technical scheme, the specific process for implementing the first-stage fracturing is as follows: firstly, injecting a certain volume of acid liquor into a shaft; then injecting a certain volume of glue solution into the shaft; further injection of slickwater into the wellbore followed by addition of proppant of different particle sizes.

According to the technical scheme, the volume of the injected acid liquid is 10-30m³The volume of the injected glue solution is 80-200m³The volume of injected water reducing is 800-³The particle size of the proppant is 106-600 um.

According to the technical scheme, the added propping agent is added in batches from small to large in particle size.

According to the technical scheme, during the second-stage fracturing construction, acid liquor and glue liquor are not injected into the shaft, but the temporary plugging ball is started to be put into after the water reducing water is directly injected.

According to the technical scheme, after the temporary blocking ball reaches the perforation, the ground construction pressure rises stably, the fact that the shot effectively blocks the perforation hole which is filled with liquid fully is shown, and the propping agents with different particle sizes are added continuously.

According to the technical scheme, the volume of injected water reducing is 800-1000m³。

The beneficial effects obtained by the invention are as follows:

the method for promoting the balanced expansion of the multiple cracks through ball throwing and temporary blocking can utilize the temporary blocking ball to realize the temporary inhibition of the dominant expansion crack on the premise of keeping the existing hydraulic fracturing construction process basically unchanged, and creates conditions for the sufficient liquid feeding expansion of the non-dominant crack, so that the unbalanced phenomenon of the mutual expansion of the multiple cracks is improved, the reservoir transformation area is enlarged, and the unconventional oil and gas recovery rate is effectively improved. The invention can not cause artificial negative influence on the existing reservoir, can be widely applied to various types of reservoirs by dynamically adjusting construction parameters, and can greatly increase the reservoir modification volume, improve the oil gas recovery ratio and reduce the unit oil gas exploitation cost.

Drawings

FIG. 1 is a schematic diagram of staged multi-cluster fracturing of a horizontal well.

FIG. 2 is a graph comparing the ideal effect and the actual effect of multiple clusters of fracture propagation in a fracturing zone.

Fig. 3 is a flowchart of a method for promoting balanced propagation of multiple clusters of fractures by ball dropping and temporary plugging according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a ball-dropping temporary plugging fracturing process proposed by the embodiment of the invention.

Detailed Description

The invention will be further explained with reference to the drawings.

Referring to fig. 3, a method for promoting balanced propagation of multiple clusters of fractures by ball dropping and temporary plugging provided by an embodiment of the present invention includes the following steps:

1) dividing the whole fracturing construction process of one fracturing section into N stages, wherein N is more than or equal to 2, and specifically setting several stages, wherein the stages can be dynamically adjusted according to site geology, engineering conditions and fracturing construction effects;

2) and (3) implementing the first stage of fracturing, wherein different fracturing fluid types and different propping agent combinations for promoting fracture initiation and expansion are involved, and the first stage of fracturing can be specifically selected according to reservoir geology and engineering characteristics.

The method specifically comprises the following steps: firstly, a certain volume of acid liquor is injected into a shaft, and the acid liquor can react with carbonate rock minerals in a near-wellbore zone after reaching a stratum, so that the fracture initiation pressure at the position of a perforation cluster is effectively reduced, and the fracture initiation and expansion are easier; secondly, glue solution with a certain volume is injected into the shaft, the viscosity of the glue solution is high, wide and large main cracks can be formed nearby the shaft, and a good initial condition is created for subsequent crack expansion; and thirdly, water reducing water is further injected into the shaft, and then proppants with different particle sizes are added, so that the viscosity of the water reducing water is low, the fractured fractures can be fully expanded to the deep part of the reservoir, and the proppants with different particle sizes can effectively support the fractures and keep long-term opening.

3) And (3) implementing second-stage fracturing, wherein acid liquor and glue liquor are not injected into the shaft in the second-stage fracturing, the water reducing and blocking water is directly injected, and meanwhile, a temporary blocking ball is added, is a degradable ball body and can temporarily and effectively block the perforation holes, so that the liquid at the perforation cluster part is limited from flowing into the stratum. After the temporary plugging ball is added, according to the fluid mechanics principle, the temporary plugging ball enters the perforation hole with the advantage of liquid inlet to plug the perforation hole, the hydraulic cracks at the position of the perforation cluster are in a fully expanded state, the expansion of the perforation cluster is inhibited after plugging, liquid in a shaft can flow to the position of the perforation cluster which is not plugged, the hydraulic cracks at the positions are further fully expanded, and the fracturing construction effect is as shown in figure 4.

4) And (3) performing the follow-up fracturing construction of several stages in the same step as the step 3, and finally completing the fracturing construction of the fracturing section.

5) And (3) continuously repeating the steps (2), (3) and (4) in the construction process of the rest fracturing sections, and finally completing the segmented multi-cluster fracturing construction of the whole horizontal section reservoir.