川南海坝区块页岩气储层裂缝发育特征与预测

Development characteristics and prediction of natural fractures within shale gas reservoirs,Haiba Block of southern Sichuan Basin

随着油气勘探开发的深入,全球化石能源结构产生重大变化,页岩气是我国当前重要的非常规能源之一,储层中天然裂缝的发育与分布对页岩气勘探开发具有重要影响。为了查明川南海坝区块页岩气储层裂缝发育分布特征,该研究基于成像测井与钻井岩芯资料,在量化表征页岩气储层裂缝参数的基础上,综合利用R/S分析法对其进行预测。研究结果表明:1)海坝区块页岩气储层天然裂缝较发育,非均质分布,Hb5和Hb7井附近裂缝密度较高;2)区内页岩气储层裂缝以垂直缝为主,其次是高角度斜交缝,水平缝不发育,裂缝优势走向方位为NW-SE向,大多数裂缝被充填,裂缝有效性相对较差;3)单井裂缝发育,总体呈现非均质分布特点,整体上,龙马溪组底部层段的裂缝发育程度较高;4)成像测井质量及裂缝特征等多因素对R/S分析法裂缝发育分布预测结果存在制约。该研究成果对川南海坝区块页岩气勘探开发具有一定的实际指导意义。

With the deepening of oil and gas exploration and development,global fossil energy structure has undergone significant changes,shale gas is an important unconventional energy in China.The development and distribution of natural fractures in shale reservoirs have important impacts on shale gas exploration and development.In order to further understand the development and distribution characteristics of shale gas reservoir fractures in the Haiba Block of southern Sichuan Basin,in this study,based on imaging logging and drilling core data,and measured fracture parameters in shale gas reservoir,the R/S analysis method is comprehensively used to predict the development and distribution characteristics of shale gas reservoir fractures.The prediction results show that:1)Natural fractures in the target shale gas reservoir of Haiba Block are relatively well developed,the fracture density is relatively high in wells Hb5 and Hb7.2)Fractures are mainly vertical fractures,followed by high angle oblique fractures.Bedding-parallel fractures are not developed.The dominant fracture strike is NE-SW trending.The majority of fractures are filled with minerals in the study area.3)Characteristics of fracture development and fracture zone distribution of a single well in the area are predicted,showing a strong anisotropy,fractures are relatively developed in the bottom of Longmaxi Formation.4)The reliability of prediction results is mainly affected by the R/S analysis method,quality of imaging logging and characteristics of fractures.The research results indicate certain guiding significances for the latter shale gas exploration and development in the Haiba Block.