Deep carbonate rock self-supporting acid fracturing method for increasing depth of acid etching crack channel

Abstract

The invention discloses a deep carbonate rock self-supporting acid fracturing method for increasing the depth of an acid etching crack channel. The deep carbonate rock self-supporting acid fracturingmethod comprises the following steps that (1), parameters are evaluated and optimized; (2), a segmented acid fracturing method is determined; (3), main cracks are constructed by low-damage high-viscosity fracturing fluid; (4), slug type shielding material injection construction is carried out and / or low-viscosity acid liquid variable-displacement viscous fingering construction is carried out; (5),medium-high displacement of low-viscosity acid liquor is carried out; (6), high-displacement injection construction of medium-viscosity acid liquid is carried out; (7), displacement operation is carried out; (8), the steps (5) to (7) are repeated until all sections are constructed; and (9), well shutdown is carried out for 1-2 hours. According to the deep carbonate rock self-supporting acid fracturing method for increasing the depth of the acid etching crack channel, the depth of the acid etching channel in the length range of the main crack can be effectively increased, the depth distribution is basically uniform, and the high-pressure resistance is higher.

Description

Technical field[0001]The invention relates to the technical field of petroleum exploitation, in particular to a deep-layer carbonate rock self-supporting acid fracturing method for increasing the depth of acid-etched crack channels.Background technique[0002]At present, more and more deep carbonate reservoirs are discovered, such as Sinopec’s Tahe Oilfield, where the buried depth is generally more than 5000m, and some even more than 6000m. For such a deep reservoir, the closure stress should be above 80-100MPa, and the conductivity of acid-etched fractures decreases rapidly, and some even drop to zero, resulting in a corresponding reduction in the effective fracture length of acid-etched fractures. Therefore, the effective period of acid fracturing of deep carbonate rocks is generally relatively short, which severely restricts economic development benefits. Therefore, how to greatly improve the conductivity of acid-etched fractures in deep carbonate reservoirs is particularly urgent....

AI Technical Summary

Problems solved by technology

[0005]However, there are still problems with the self-supporting acid fracturing technology for rocks mentioned above. For example, the depth of the acid-etched fracture channel is not enough. At the middle and far ends of the fracture, the etch depth of the middle and far ends of the fracture is reduced due to the smaller and smaller etching ability of the acid. At this time, when the underground fluid flows, if the etch depth of the channel is small, it is easy to be affected by the unevenness of the fracture surface. , so the diversion capacity is greatly affected

[0006] Chinese patent CN102174883A discloses a test method for the conductivity of self-supporting fractures of clear water fracturing, which is used for the lack of conductivity of self-supporting fractures of clear water fracturing in the current oil and gas field development process The problem of laboratory testing and evaluation methods does not involve how to increase the complexity of fractures and stimulated volume in deep shale fracturing operations

[0007] Chinese patent CN107578471A discloses a method for constructing the initial shape of self-supporting fractures, which can accurately construct the initial shape of self-supporting fractures, and then provide production prediction and stimulation after clear water fracturing Potential evaluation provides effective guidance, but does not involve how to increase the complexity of fractures and stimulated volume in deep shale fracturing operations