Study On The Characteristics Of Formation Pressures For High-temperature And High-pressure Block In South Sea

Given the phenomena that the exploration of oil and gas is becoming more and more burdensome,the structural features of the exploration and development blocks became more complex,and the deep or ultra-deep wells will prevalent in future,which results in increasing the trend of drilling HPHT layers and triggering more complex wellbore spray accidents such as leak,collapse,cards.This study will provide a good,economic and security assessment method for the oil exploration and development.Specific contents of this paper are as follows:(1)Establishing Porous elastic model.In this paper,the wall rock stress distribution equation is set up,namely porous elastic model,on the basis of the original model of linear elasticity theory,considering the effect of reservoir flowing solid coupling effect on the in situ stress field,the plane strain state,generalized Hu-Ke law,effective stress law,elasticity theory equations and linear Navier superposition principle.(2)Laboratory evaluation experiments.This study sets the full diameter core as the main subject and uses triaxial experimental system,the pressure transmission test systems,acoustic tester and other equipment fully testing this dynamic and static elastic modulus and Poisson’s ratio batch cores,cohesion internal friction angle,Biot coefficient,uniaxial compressive strength and tensile elastic strength and other parameters,and uses the permeability and porosity tester the core of physical parameters-permeability and porosity for the subsequent model calculations provided basic data.(3)Establishing a multi-factor logging interpretation model of rock mechanics parameters.This study combines the static indoor rock mechanics test results and field data logging as the main research objective,explores sensitive factors and the best fit functions of every rock mechanics parameters;then,using genetic algorithms as the major data iterative algorithm to fit log data acquisition static parameters of rock multivariate interpretation models;compared with the existing empirical models,this explanation model has significant advantages and a higher degree of fit,which may satisfy the engineering applications and computing demands.(4)Three Strata pressure characteristics.On the basis of this part of the porous elastic theory model,the strength parameters and reservoir rocks logging data,using sonic time difference-Eaton formula can get the pore pressure on the entire wellbore profile,through Coulomb-Mohr failure criterion of rock collapse pressure of the blocks of rock can be calculated,and by the tensile failure criterion we can obtain burst pressure of rock formation.In the last,the study evaluates the characteristics of formation pressures to identify the abnormal high pressure horizons and collapse leaky horizons easily,and pointes out the corresponding countermeasures.