川西低渗气藏单井地应力计算方法综合研究

四川盆地新场气田是一个低孔低渗的裂缝性砂岩气田，储层物性差，自然产能低，需经压裂后才能投产，压裂后气井增加的产能与压裂的效果密切相关。提前认识储层当前地应力的特征，有助于压裂设计时确定裂缝产状、缝长、缝宽等参数，减少储层水力压裂改造的盲目性，降低中、低渗透油气田开发的风险。通过大量测井资料的计算，确定了新场气田储层地应力的大小和方向，并综合采用微地震测量、岩石声发射资料、古地磁等岩心测试资料和水力压裂等多种方法进行交互验证，各种方法求得的地应力特征十分相近，说明利用测井资料求取储集层地应力原理简单，计算结果符合实际的地应力特征，是一种低风险研究计算储层地应力特征的方法，可以用于指导低渗透油气田的井网部署和储层的单井压裂改造。

COMPREHENSIVE STUDY OF CALCULATION PROCEDURE OF SINGLE WELL TERRESTRIAL STRESS IN LOW-PERMEABILITY GAS RESERVOIR IN WESTERN SICHUAN BASIN

Xinchang gas field in Sichuan Basin, a fractured sandstone gas field with low porosity and low permeability, is characterized by poor poroperm characteristics and low natural deliverability. Fracturing has to be performed before gas wells can be brought on line and the incremental deliverability of gas wells after stimulation depends heavily on effects of fracturing operation. A thorough understanding of the current terrestrial stress of reservoirs can help to calculate parameters such as occurrence, length and width of fractures in fracturing design, to reduce blindness of hydraulic fracturing operation, and to lower the development risk of oil/gas fields with medium or low permeability. The values and orientations of reservoir terrestrial stress in Xinchang gas field are determined through calculation of large amount of logging data and are mutually verified by comprehensively using microseismic survey, rock acoustic emission data, palaeomagnetic data and hydraulic fracturing. The features of terrestrial stress obtained by using different methods are very close. Calculation of reservoir terrestrial stress with logging data is simple and the results accord with the real situations. It is a low-risk method for calculating reservoir terrestrial stress and can be used to guide well pattern deployment and single well fracturing in low-permeability oil/gas fields.