南川地区茅口组-栖霞组气藏认识

Understandings of Maokou Formation-Qixia Formation Gas Reservoirs in Nanchuan Area

通过地质特征、压裂特征和实钻资料,对川东南南川地区茅口组-栖霞组碳酸盐岩气藏进行了研究,认为茅口组底部TOC含量较高、孔渗条件较好、裂缝发育、脆性高、碳酸盐含量高、含气性良好,是地质-工程的双甜点区域;气藏中硫化氢来源于含硫有机物热裂解,其浓度与气藏压力呈负相关,与采出地层水呈正相关。茅口组-栖霞组气藏来自下志留系龙马溪组和茅口组的共同贡献,成藏受控于岩溶风化作用、规模化断层和大型基底断裂。

Based on geological characteristics, fracturing characteristics and actual drilling data, the Maokou Formation-Qixia formation carbonate gas reservoir in the Nanchuan area of southeastern Sichuan was studied. It is believed that the bottom of Maokou formation has high TOC content, good porosity and permeability, well-developed fractures, high brittleness, and carbonate content, with high gas content, it is a sweet spot of geology and engineering. H2S in the gas reservoir comes from the thermal cracking of sulfur-containing organic matter, and its concentration is negatively correlated with gas reservoir pressure and positively correlated with produced formation water. The Maokou formationQixia formation gas reservoir comes from the joint contribution of the lower Silurian Longmaxi formation and the Maokou formation, and its accumulation is controlled by karst weathering, large-scale faults and basement faults.