川南地区龙潭组煤系气藏特征及地球物理勘探方法

Coal-measure gas reservoir characteristics and geophysical exploration method of Longtan formation in south Sichuan area

1.四川省地质调查研究院,四川成都610072;
2.四川中成煤田物探工程院有限公司,四川成都610072

1. Geological Survey of Sichuan Province,Chengdu 610072,China;
2. Sichuan Zhongcheng Coalfield Geophysical Engineering Institute Co.,Ltd.,Chengdu 610072,China

为提高煤系气单井产量,需要探明煤系地层中煤系气、泥页岩气、致密砂岩气等烷烃储层资源条件与开采条件。简要分析了川南地区龙潭组煤系气藏地质特征,发现川南煤系气藏呈现以泥岩煤层泥岩地层为主的叠置组合模式,富含Ⅲ型干酪根,具有变质程度高、有机碳含量高、含气量高的特点。煤系上覆长兴灰岩、下伏茅口灰岩地层,存在较大的密度差异,为地震、测井探测提供了良好的地球物理基础。在川南煤系气勘探与开发中,采用地质物探综合勘探方法,在测井信息约束下,利用相位、振幅、弹性阻抗等地震属性解释煤系气藏的分布特征并预测厚度与含气量,形成了川南地区煤系气藏识别的地震勘探关键技术。上述技术在大村勘探区取得了良好的应用效果,可为川南地区油气产能建设规划提供地质资料支撑。

To improve the production of coalbed methane (CBM) in a single well,the resource and exploitation conditions of alkane gases,such as CBM,shale gas,and tight sandstone gas,must be explored in coal-measure strata.In southern Sichuan,the coal measure strata are dominated by superimposed combinations of mudstone-coal seam-mudstone.Coal measures are rich in type III kerogen,characterized by high evolution,rich in organic carbon,and high gas content.The overlying Changxing Limestone and underlying Maokou limestone of the coal-measure have substantial density differences,which benefit the implementation of seismic and logging exploration.In this study,we summarized the development of coalbed methane and the studies on shale gas and tight gas in southern Sichuan.For the exploration and development of coal measure gas in southern Sichuan,we adopted a comprehensive geological geophysical exploration method,and we used the phase,amplitude,elastic impedance,and other seismic attributes to interpret the distribution,thickness,and gas content prediction of coal-measure gas reservoirs under the constraint of logging information.We thus formed the key seismic exploration technology for identifying coal measure gas reservoirs in southern Sichuan,which achieved a high-quality application in the Dacun exploration area.This can effectively provide geological support for the planning of oil and gas production capacity in southern Sichuan.

四川省重点科技攻关项目“煤系中页岩气与煤系气共采先导性技术及试验研究”(2016jz0037)资助。

10.3969/j.issn.1000-1441.2023.01.004