塔中隆起奥陶系储层与油源断裂复合控藏模式

Composite Controls on Oil and Gas Accumulation by Fractures in Source Rocks and Ordovician Reservoirs in the Tazhong Uplift

沈卫兵 陈践发 罗广平 贺礼文

SHENWeibing CHENJianfa LUOGuangping HELiwen

“深地动力学”自然资源部重点实验室·中国地质科学院地质研究所, 北京 西城 100037 “油气资源与探测”国家重点实验室·中国石油大学(北京), 北京 昌平 102249

MLR Key Laboratory of Deep-Earth Dynamics, Institute of Geology, Chinese Acadeym of Geological Sciences, Xicheng, Beijing 100037, China State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Changping, Beijing 102249, China

基于现有油、气、水勘探成果及储层、断裂资料，利用常规测井、地震、地化及数理统计等多种方法，对塔中隆起奥陶系油气分布及成藏特征开展研究。结果表明，奥陶系储层以礁滩沉积为基础，发育大量溶蚀孔洞及裂缝，控制了油气相对高孔渗富集。储层孔隙度和渗透率越大，与围岩之间的毛细管力差就越大，含油气概率越大、含油饱和度越高，存在油气富集的临界毛细管力（2.5 MPa）。奥陶系油源断裂交汇处为油气优先充注点，控制了油气的近源富集。距离充注点越远，油气充注强度越小，油气产能越低，油气地球化学性质规律性变化，存在油气富集的临界距离（距充注点20 km）。在储层和油源断裂联合控制下，塔中隆起奥陶系油气富集呈"近充注点-相对高孔"的地质模式，于充注点近端的高孔渗储层内优先成藏。

In this study, existing oil, gas and water exploration results and information on reservoirs and fractures were used and various methods employed, including conventional borehole logging, seismology, geochemistry, and mathematical statistics. The goal of this synthesis of methodology and data was to examine the distributions and accumulation characteristics of oil and gas in the target layers in the study area. The results reveal that the Ordovician reservoirs are mainly composed of reef beach sediments. There are numerous karst caves and fractures, which control the relatively high-permeability accumulation of oil and gas. As porosity and permeability of a reservoir increase, capillary force differences between the reservoir and its surrounding rocks increase. Consequently, there is a higher probability that the reservoir contains oil and gas, and the degree of oil saturation increases. The critical capillary force for oil and gas accumulation is 2.5 MPa. Fractures in Ordovician source rocks show complicated distributions. They intersect each other to form ten oil and gas filling points, and control oil and gas accumulation near these filling points. When far away from these points, oil and gas filling becomes less intense and their yield decreases. The geochemical properties of oil and gas show regular variations. The critical distance for oil and gas accumulation is 20 km from a filling point. Under the joint control from reservoirs and fractures in source rocks, oil and gas show an accumulation mode characterizing "relatively high permeability near filling points" in which reserves are first formed near filling points in high-permeability reservoirs.

10.11885/j.issn.1674-5086.2017.11.26.01