Cracked formation well wall crack propagation pressure prediction method

Abstract

The invention discloses a cracked formation well wall crack propagation pressure prediction method which comprises the following steps of: establishing a two-dimensional displacement discontinuous equation of elastic deformation of a well wall and rocks around a crack, and giving initial and boundary conditions; establishing a local continuity equation of fluid flow in the crack according to fluidmass conservation; carrying out numerical solution on the established equation, and giving out a cracked formation well wall crack propagation pressure flow-solid coupling numerical model integral solving method; substituting formation crustal stress parameters, rock mechanical parameters, crack geometric parameters, fluid parameters and construction parameters into the crack propagation pressureflow-solid coupling numerical model, and simulating response characteristics and crack propagation dynamics of the well wall pressure under the condition of constant flow injection. According to theinvention, deformation and flow coupling characteristics of a stratum well wall-crack system can be considered, the well wall crack propagation pressure and crack propagation behaviors are accuratelypredicted, and scientific basis is provided for guiding crack formation drilling and completion optimization design.

Description

technical field [0001] The invention relates to the technical field of unconventional oil and gas drilling, in particular to a method for predicting the fracture propagation pressure of the borehole wall of a fractured formation. Background technique [0002] my country's unconventional oil and gas resources are rich in reserves and have great potential for exploitation. They are playing an increasingly important role in increasing reserves and production of oil and gas resources and alleviating the energy crisis. Taking shale gas as an example, horizontal well technology, as an essential technical means for the commercial development of shale gas, has been widely used in the exploration and development of shale oil and gas in China and North America. However, the development of bedding fractures in shale formations, unreasonable design of drilling fluid density during drilling, and pressure fluctuations in wells often lead to the expansion of wellbore fractures and induce l...

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Problems solved by technology

However, the extended finite element method is difficult to consider the elastic deformation of the wellbore-fracture system and the interaction between hydraulic fractures and natural fractures, and ignores the competitive flow and friction characteristics between the wellbore fractures, resulting in the prediction of the wellbore fracture propagation pressure. Big difference from the actual situation

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