现今地应力场特征综合评价技术在川西XC气田深层中的应用

APPLICATION OF SYNTHETIC EVALUATION FOR PRESENT GROUND STRESS FIELD IN DEEP FORMATION OF XC GAS FIELD IN WESTERN SICHUAN

针对川西XC气田须家河组低孔低渗透致密砂岩储层,主要研究其现今地应力场纵横向分布规律及其地质影响因素。根据水力压裂和测井资料综合计算现今地应力大小,以压裂资料结果来对测井计算值进行校正,并对测井地应力计算模型中的关键参数进行深入研究,以进一步确定出单井的地应力剖面以及各主力砂组的地应力分布。研究结果表明,该区须二段的现今地应力状态为SH>Sv>Sh,各主力砂组最大水平主应力均值在153 MPa^173 MPa之间,最小水平主应力均值在102 MPa^111 MPa之间;各水平地应力值随深度的增加而变大,与深度之间有较好的线性相关关系;最大水平主应力方向NE80°~100°,主体方位与区域构造应力作用主方向一致。区域上,构造高部位的地应力值相对较低,向翼部逐渐增大,而在断层位置的地应力值也相对低。研究区现今地应力场分布受构造形态和断层的影响较大,特别是断层的应力扩散及端部应力集中效应影响了地应力场的正常分布,使地应力值和方向发生局部变化。

In this paper,the longitudinal and horizontal distribution law of present ground stress and geological influence factors are researched for T3x2 low-porosity and low-permeability compact sandstone reservoir of XC Gas field in western Sichuan.Stress values are calculated by using logging data and hydraulic fracture data which are also used to rectify the logging calculated result.In addition,the key parameters in logging calculating stress model are investigated for further determination of stress section of single well,and for the ground stress distribution of each main layer.The results make it clear that the stress state of T3x2 formation in this area is SH SvSh,the average horizontal maximum stress are between 153 MPa～173 MPa,and the average horizontal minimum stress are between 102 MPa～111 MPa for main layers.The horizontal ground stress values increase with increase of formation depth and there is a good linear relationship between horizontal ground stress and vertical depth.The direction of horizontal maximum stress is in NE80°～100°,its principal direction coincides with principal stress direction of regional tectonics in this area.In the region,the value of ground stress is relatively smaller in high position of T3x2 structure,relatively larger in flank position of structure,and also relatively smaller in the position of faults.The distribution of present ground stress field in this region is under the great influence of the form of structure and faults,the stress diffusion in faults and stress concentration effect in terminal position of faults affect especially the normal distribution of ground stress field,which causes localized variation in ground stress values and direction.