Geomechanics Characteristics And Fracturing Technical Countermeasures Of Keshen Zone In Kuqa

In recent years,the exploration and development of Kelasu tectonic in Kuqa belt is rich.However,due to its complex geological structure,there are so many problems such as wall stability during drilling and high pump pressure during reservoir stimulation.Therefore,in the process of gas field development,it is very important to solve the problems encountered in drilling and completion through studying the characteristics of reservoir rock mechanics and the relationship with natural fractures.This paper mainly focus on the two key problems,first one,the fracture development of the low-porosity and low-permeability reservoir of in Kenshen area is unclear;the second one,the effect of reservoir fracturing is seriously constrained by the complex fractures and stress field.For the actual needs of exploration and development,according to geological data,logging data,drilling and rock mechanics experiments,the fine one-dimensional and three-dimensional model of the single well rock mechanic is established based on the analysis of the tectonic stress field and wellbore stress characteristics,which studies the present stress characteristics of the field.On the basis above,the influence of stress field and fracture profile on the fracture orientation is further analyzed to provide the basis for the stimulation measures of the target layer.The results show that,in general,the rock strength,elastic modulus,Poisson's ratio and internal friction coefficient increase with the depth of the individual wells.The Young's modulus increases with the increase of confining pressure,but the stress dependence of Young's modulus is affected by lithology,stress level and stress path.Generally speaking,the low principal stress of the same strata is larger,and the high position is more prone to strike-slip stress distribution.The three-dimensional model confirms that the fault has a significant effect on the magnitude and direction of the original stress.In the vicinity of thefault,the horizontal stress direction has a certain deflection,and the maximum principal stress on the vertical section tends to be parallel to the cross section,while the magnitude of the stress has some decline.In order to improve the reliability of the three-dimensional model,it is necessary to carry out the interpretation of seismic treatment and reduce the uncertainty of geological model and geological structure.Based on the study of the main factors of production capacity,the effective normal stress and Young's modulus were used to quantitatively calculate the natural fracture permeability and single well productivity.According to these two parameters,all wells are divided into three categories,and different stimulation programs were put forward respectively.In addition,according to the analysis of the fracture pressure and the instantaneous pump stop pressure,the minimum horizontal principal stress determines the ease of initiation,and the effective normal stress determines the difficulty of the extension of artificial fracture.In the fracturing design,this two parameters need to be considered for completion optimization,which can effectively reduce the construction pressure,thus reducing the difficulty and increasing safety of the fracturing construction.