东濮凹陷三叠系砂岩潜山油气藏裂缝特征

东濮凹陷中生界三叠系砂岩潜山油气藏为典型的低孔特低渗透储层。受岩性、岩层厚度、构造等因素的控制作用，储层中发育不同规模的裂缝系统，它们不仅提供了储集层油气的主要储集空间，而且提供了油气的主要渗流通道。通过地表露头、岩心、薄片和成像测井等资料综合研究，东濮凹陷北部三叠系砂岩潜山油气藏主要发育北北东向、北东向和近东西向3组高角度构造裂缝，具有节理型裂缝和断层型裂缝2种类型，此外还有与层面近平行的成岩裂缝。在纵向上，该区以二马营组2砂组裂缝最发育，其次是二马营组3砂组和二马营组1砂组，而和尚沟组和刘家沟组裂缝的发育程度明显变差。在横向上，裂缝沿地垒构造高部位呈带状分布，其中“人”字形和“入”字形构造样式的裂缝发育最好。

Fracture characteristics of buried-hill reservoirs of Triassic sandstone in the north of Dongpu Depression

The buried-hill reservoirs of Triassic sandstone in Dongpu Depression are typical reservoirs of low porosity and ultralow permeability. Controlled by factors of litbology, thickness and structure, there developed fracture systems of different scales in the sandstone reservoirs, which provides not only reservoir space but also the seepage channel for oil and gas. According to data of outcrops, cores, slices and imaging logging, there mainly developed three sets of tectonic fracture with NNE, NE and EW orientations and high dip angles. These tectonic fractures show two types of jointed-fracture and faulted-fracture. In addition, there also developed diagenetic fractures approximately parallel to bedding. In vertical, fractures in the second Member of the Ermaying Formation are the most developed, followed by the first and third member of the Ermaying Formation, and last the Heshanggou Formation and Liujiagou Formation where fractures are poorly developed. Laterally, the developed fractures distribute in belts along structural high of the horst. Fractures are well developed at the structural styles where a main fault reaches a secondary fault or vice versa.