绵阳-长宁“侵蚀槽”发育特征及其对油气成藏的控制作用

Development characteristics of Mianyang Changning“erosion trough”and its controlling effect on oil and gas accumulation

四川盆地绵阳-长宁“侵蚀槽”对震旦系-寒武系特大型天然气藏的形成和分布具有重要控制作用。基于最新钻井和地震资料进一步明确了绵阳-长宁“侵蚀槽”具有“北深南浅、南北分段、向南北开口”的平面展布特征和类似于现代侵蚀地貌的剖面特征。绵阳-长宁“侵蚀槽”可分为灯二段和灯四段两期“槽盆”,充填了较为完整的下寒武统麦地坪组-筇竹寺组,麦地坪组~筇竹寺组三段表现为超覆充填沉积,筇竹寺组四段表现为广覆式填平补齐沉积。对比研究表明绵阳-长宁“侵蚀槽”明显控制了优质烃源岩、规模优质储层和气藏的分布,“侵蚀槽”内部和两侧具备“上生下储”和“旁生侧储”的成藏配置关系,阆中、资阳和知新场地区是下一步油气勘探重点区域。

Mianyang Changning erosion trough in Sichuan Basin plays an important role in controlling the formation and distribution of super large Sinian-Cambrian natural gas reservoirs.Based on the latest drilling and seismic data,this paper further defines the plane distribution characteristics of Mianyang Changning erosion trough,which is deep in the north and shallow in the south,segmented in the north and opened in the south,and the profile characteristics of the erosion trough is similar to modern erosion landforms.The Mianyang and Changning erosion trough can be divided into two stages of 2th member and 4th member of the Dengying Formation,which were filled with relatively complete Lower Cambrian Maidiping Formation and Qiongzhusi Formation.The early stage of the‘erosion trough’was filled by Maidiping Formation and 1-3th member of the Qiongzhusi Formation,and the late stage was filled by the 4th member of Qiongzhusi Formation.A comparative study indicates that the Mianyang-Changning erosion trough clearly controls the distribution of high-quality hydrocarbon source rocks,large-scale high-quality reservoirs,and gas fields.The erosion trough has a configuration of‘upper generation and lower reservoir’and‘paragenetic and lateral reservoir’within and on both sides of the trough,and Langzhong,Ziyang and Zhixinchang are the key areas for oil and gas exploration.