Study On Hashan Deep Igneous Reservoir Structure Characteristics And Distribution Of Wellbore Stress

As the world's conventional oil and gas production and reserves continue to decline,oil field exploration and development gradually extend to unconventional oil and gas fields.The exploration and development of deep igneous reservoirs is becoming more and more important,which has gradually become a hot research topic in the field.Studying on the structure characteristics of igneous rock is a very important content of the comprehensive evaluation of reservoir.Ground stress is the stress in the earth's crust.It is an important research object in oil exploration and development,which affects the development of the fracture.Sidewall stability is a common problem in the process of drilling,and the wellbore stress has great influence on the sidewall stability.So in this paper,based on previous studies,taking hashen2 well as example,studied the hashan deep igneous reservoir structure characteristics and distribution of wellbore stress.The main research work and achievements are reflected in the following aspects:(1)The rock mechanical parameters were calculated by oilfield test logging data.This is an economical,simple and high reliability method.Applied the mechanical parameters to identify lithologic,combining with the cross plot as a multi-parameter method,which is an innovative method to identify lithology.Finally find that there are six major categories in study area.(2)The structural characteristics of rock in the study area were analyzed by well logging data,mainly analyzed from the porosity and permeability two aspects.It is found that the fracture and porosity are relatively developed in the study area,and the reservoir space is mainly the fracture and pore.(3)The ground stress distribution and fracture development situation in the study area were studied.Using well logging data,based on the Huang's empirical model,the maximum and minimum principal stresses of different depth strata were calculated.(4)A three-dimensional model of borehole was established,and the borehole stress distribution was analyzed the finite element numerical simulation method.The overall stress distribution and the borehole wall stress distribution in the study area were obtained.(5)When studied on the sidewall stability problem,it was different from the previous simulating with a two-dimensional plane model,a three-dimensional model was used for overall analysis.Compared with each other between three kinds of failure criterion,finally it determines that the Mohr-Coulomb criterion is more appropriate for the well area.The density range of drilling fluid and collapse pressure gradient were calculated.But drilling fluid density actually used is less,prone to overflow,so propose to increase the drilling fluid density.