张性断裂交汇部位油气运聚机理及有利类型预测

Plenty of oilfield examples confirmed that the role of the intersection part of faults in hydrocarbon accumulation is very complex, it can be high yield area of hydrocarbon, as well as leakage area, the risk of exploration is very great, and it is difficult for the present oilfield exploration. To find out the mechanism of hydrocarbon accumulation or migration in intersection part of faults, taking the structure of Daliuquan of Langgu Sag in Jizhong Oilfield as an example, fault system and oil source faults are determinates based on the fault geometry and kinematic analysis, then the faults can be comprehensive classified according to the throw, evolution stage of intersection faults, as well as whether the faults are oil source faults. Then with constraint of core test and logging data, the stress, distribution of fractures, clay content of fault condensed zone in reservoir and caprock of the intersection part of faults are obtained by numerical simulation of pre-stack seismic data, then the faults activities in period of hydrocarbon migration and accumulation are calculated. Finally, determined the key factors of hydrocarbon migration and accumulation in intersection part of faults based on the above analysis, then summarized the accumulation mechanism of hydrocarbon in intersection part of tensional faults by comparing the dynamic data of hydrocarbon reservoir whether succeed or not, as well as geochemical tracing parameters. Establish a (semi-) quantitative criterion for the intersection part as hydrocarbon accumulation area or migration path, predict the favorable types of fault intersect and optimize the accumulation targets.

大量的油田实例证实，断裂交汇部位在油气成藏中的作用非常复杂，既可能是油气高产区，又可能是油气泄露的失利区，勘探风险极大，给目前油田的勘探部署造成很大困难。为了查明断裂交汇部位油气富集或运移泄露的机理，以冀中廊固凹陷大柳泉构造为靶区，在断裂几何学及运动学分析基础上厘定断裂系统及油源断裂，并根据两组交汇断裂的断距变化、演化阶段及是否为油源断裂等进行综合分类；其次，以岩心测试及测井资料为约束，应用叠前地震数据进行数值模拟，获得断裂交汇部位的应力（变）、裂缝分布及储层、盖层段断裂带泥质含量，并计算该部位油气运移期、保存期的断裂活动强度；最后，综合以上分析确定出断裂交汇部位油气运移、聚集的关键影响因素，并结合成功、失利的油气藏动态数据及地球化学示踪参数总结张性断裂交汇部位油气运聚机理，建立该部位作为油气富集区或油气运移通道的（半）定量判别标准，并预测有利的断裂交汇类型，优选成藏目标。

以廊固凹陷大柳泉地区为研究目标区，从断裂几何学、运动学研究出发并总结断裂交汇类型，并对不同的断裂交汇类型进行数值模拟，计算出交汇区应力、应变，裂缝分布和泥质含量，结合油藏解剖总结了断裂交汇部位油气运聚成藏的机理。对于按断层活动强度组合的断裂交汇模型模拟结果表明，（1）断层交汇类型中处于倾向共同所指的一侧的正断层交汇处，是较大沉降位移分布区，一般处于凹陷沉降中心，是烃源岩发育及油气生成中心，有利于为生成油气；（2）在断层交汇类型中处于相反一侧的正断层交汇处，是较大垂直位移上升分布区，一般处于隆起地带，即处于油气主要运移指向区，圈闭发育，有利于油气的富集