Method and device for predicting drilling fluid leakage of fractured formation by using DFN

Abstract

The invention relates to a method for predicting drilling fluid leakage of a fractured formation by using DFN. The method comprises the following steps: determining rock mechanical parameters; determining an underground fracture distribution function model; a random fracture model is generated based on a Monte-Carlo method; acquiring ground stress parameters and fluid parameters of the well drilling; establishing a drilling fluid seepage borehole model by utilizing two-dimensional discrete element software; inputting the obtained rock mechanical parameters, the random fracture model, the crustal stress parameters and the fluid parameters into a drilling fluid seepage borehole model, endowing wellbore liquid column pressure and pore pressure to a borehole, setting certain drilling fluid leakage flow, and calculating by two-dimensional discrete element software to obtain a drilling fluid seepage borehole model after balance is achieved. The seepage condition of the drilling fluid around the well in the crack is observed and counted, and the seepage condition comprises the flow speed and the fluid pressure of the drilling fluid; the seepage flow output by the borehole model is calculated, the seepage flow and the drilling fluid leakage flow are compared and analyzed, and the accuracy of the borehole model is verified.

Description

technical field [0001] The invention relates to the technical field of oil and gas development, in particular to a method and a device for predicting the loss of drilling fluid in a fractured formation by using DFN (discrete fracture network). Background technique [0002] With the increase of the exploitation depth of oil and gas resources, the problem of drilling fluid leakage caused by the complex geological characteristics of deep and unconventional formations frequently occurs. During the drilling process, the main reason for the leakage of drilling fluid is the fractured leakage caused by the opening of drilling-induced fractures and natural fractures. The existence of fractures exacerbates the loss of drilling fluid from the wellbore to the formation, contaminates the formation near the wellbore, and causes a lot of economic losses and reduced recovery. [0003] Most of the existing prediction and simulation methods are based on the conventional uniform fracture dist...

AI Technical Summary

Problems solved by technology

The existence of fractures intensifies the loss of drilling fluid from the wellbore to the formation, pollutes the formation near the wellbore, and causes a large number of economic losses and a reduction in recovery

[0003] Most of the existing prediction and simulation methods are based on conventional uniform fracture distribution models, which cannot reflect the real situation of downhole fractured formation loss

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