Crack initiation and propagation and supporting crack stress sensitivity evaluation device and method

Abstract

The invention relates to a crack initiation and propagation and supporting crack stress sensitivity evaluation device and method. The device comprises a core part, a confining pressure loading part, afracturing fluid pumping part, a stress sensitivity test part and a crack monitoring part. The method comprises: step 1, setting X, Z, and Z triaxial pressures, and applying triaxial load to a core;step 2, calculating the uniaxial permeability or the triaxial overall permeability of the core flowing from a shaft to a reservoir or from the reservoir to the shaft; step 3, adding fracturing fluid into an intermediate container I as prepad fluid, and adding the fracturing fluid and a proppant into an intermediate container II as sand carrying fluid; step 4, injecting the prepad fluid into the core and injecting the sand-carrying fluid into the core after the core is pressed open; and step 5, injecting water or gas into the shaft or a triaxial seepage plate, and calculating the uniaxial permeability or triaxial overall permeability of the core flowing from the shaft to the reservoir or from the reservoir to the shaft after fracturing. The crack initiation and propagation and supporting crack stress sensitivity evaluation device and method can guide the optimization of hydraulic fracturing construction parameters and effectively improve the productivity of oil and gas wells.

Description

technical field [0001] The invention belongs to the field of oil and gas field development, and in particular relates to an integrated device and method for fracture initiation and expansion and support fracture stress sensitivity evaluation. Background technique [0002] In the process of exploration and development of unconventional oil and gas resources, hydraulic fracturing technology has always played a vital role. Because the physical properties such as porosity and permeability of unconventional reservoirs are generally poor, most of the production wells will be implemented before they are put into production. Transformation measures to increase production. Hydraulic fracturing technology is a common means to efficiently increase the productivity of a single well. The core of its production stimulation is to provide a high-speed channel for oil and gas to flow into the wellbore through the conductivity of hydraulic fractures, and to enhance the connectivity between th...

AI Technical Summary

Problems solved by technology

At present, the main means to study the initiation and expansion of hydraulic fractures are numerical simulation and indoor core fracturing simulation tests, and the main means to study the stress sensitivity of fractures is to test the variation of permeability with stress in small columnar cores (generally less than 10 cm in diameter). These methods all have certain deficiencies and limitations:

[0006] (3) The fracture stress sensitivity test has the following problems: the core size and the fracture size are too small; the fracture is generally created by artificial splitting, which is not a real hydraulic fracture; the proppant in the fracture is added in advance, not through fracturing Liquid is carried in; only one-way seepage can be simulated, and the seepage pattern around the wellbore cannot be simulated; the method of applying confining pressure is to wrap and pressurize the entire cylinder of the core, but not true triaxial pressurization, so it has great limitations

Images