Method for changing volume of crack and its application

Abstract

The invention relates to a method for changing the volume of a crack and its application. The method includes the following steps that 1, the characteristic parameter of a reservoir is evaluated, wherein the characteristic parameter includes a brittleness index, a natural fracture development degree and a horizontal stress difference coefficient; 2, the type and use amount of an adopted propping agent is determined through simulation software; 3, liquid of the propping agent determined in the step 2 is used for fracturing transformation of the reservoir. The provided method for changing the volume of the crack is reasonable and simple in design, calculation and operation are easy to conduct, the changed volume of the crack can be effectively improved, the filling degree of cracks differentin scales, the yield-increasing effect is improved to the greatest extent after pressing, and the decline rate of yield is delayed.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploration, and in particular relates to a method for reforming fracture volume in shale gas volume fracturing. Background technique [0002] At present, shale gas volume fracturing has been carried out in China for nearly five years in theoretical research and field tests, and commercial breakthroughs have been achieved in Fuling of Sinopec and Changning-Weiyuan of PetroChina. Researches on shale gas fracability evaluation, physical model of shale fracture propagation, conductivity characteristics of complex fractures, development of high-efficiency slick water and glue, development of staged fracturing tools, and post-fracture flowback and post-evaluation have been carried out. Basically mature and complete supporting facilities. However, in terms of technology, especially the optimization of proppant and the injection mode, it needs to be further refined and improved. The existing method of...

AI Technical Summary

Problems solved by technology

[0004] (1) The type of proppant selected is single

The combination of 70 / 140 mesh (usually called 100 mesh), 40 / 70 mesh and 30 / 50 mesh three types of proppants has become a general model and is widely used in various shale reservoirs, but there is no Considering the characteristics of specific shale reservoirs, the development of fractures, and the mechanical properties of shale rocks, the particle size of the added proppant may not match the size of the fracture, making it difficult to add proppant and may cause early sand plugging. And other issues

[0005] (2) Single proppant injection mode

This injection mode is consistent with the fracture width variation trend during the fracture propagation process, but due to the strong randomness of shale homogeneity and distribution of natural fractures, it is difficult to ensure the appropriate proportion of the above three proppants. Improper proppant ratio will either affect post-fracturing production or cause early sand plugging, which is very unfavorable

[0006] (3) The usage ratio of proppants with different particle sizes is generally based on experience, and there is no scientific and feasible design basis

But in fact, the development and distribution of natural fractures are very random

In addition, the addition of low-viscosity liquid further expands the natural fracture system of different scales, making the design of 100-mesh proppant less targeted

Less 100-mesh proppant is used, the plugging efficiency of natural fractures and bedding / textured fracture systems is low, and the propping efficiency is also low, which has a greater impact on production decline after fracturing