顺北地区走滑断裂与断溶体圈闭识别描述技术

Identification and characterization of strike-slip faults and traps of fault-karst reservoir in Shunbei area

顺北地区奥陶系目的层主要发育洞穴型、裂缝型和孔洞型3种类型储层,储层非均质性强,且储集规模受多期活动走滑断裂体系控制。已钻井揭示的断溶体储层地震响应特征多样,预测与描述难度大。断溶体圈闭是一种与喀斯特岩溶缝洞型圈闭有较大差异,在复杂条件下形成的特殊碳酸盐岩缝洞型圈闭,具有纵向跨越深度大、横向非均质性强、不受局部构造形态控制、无统一油水界面、上覆区域泥岩顶封、致密碳酸盐岩可侧封的特点。在前期研究认识基础上,通过模型正演,结合井震标定及地震反射特征分析,建立了走滑断裂、断控缝洞储集体地震识别模式,形成了梯度结构张量定断溶体轮廓,振幅变化率、杂乱相属性等分类预测断裂带内部储层,多属性融合雕刻描述断溶体的储层识别描述技术;建立了断溶体识别与圈闭描述技术。该技术的应用指导了顺北地区多口井部署并实现油气重大突破,储层钻遇率达84%,证实了技术的有效性及适用性,为顺北油气田和其他地区识别及描述断溶体提供了解决方法和技术参考,对顺北油田超深层领域断溶体勘探开发具有重要意义。

There are mainly 3 types of reservoirs in the Ordovician objective strata in the Shunbei area:cave type,fracture type and vuggy type.Reservoir is characterized by strong heterogeneity,and reservoir scale is controlled by strike-slip fault system with multi-stage activities.The seismic response characteristics of fault-karst reservoirs penetrated by wells are various,which is difficult to predict and describe.Different from karst fracture-cavity trap,trap of fault-karst reservoir is a kind of special carbonate fracture-cavity trap formed under complex conditions.It is characterized by large vertical range and strong horizontal heterogeneity.It is not controlled by partial structure morphology,with no unified oil-water contact.The top sealing is provided by the regional overlying mudstone,and the lateral sealing can be provided by tight carbonate rocks.On the basis of previous researches and understandings,through forward modeling,well-seismic calibration and seismic reflection characteristics analysis,the seismic identification modes of strike-slip faults and fault-controlled fracture-cavity reservoirs have been established.Reservoir identification and description technologies have been formed,that is,using gradient structure tensor to determine the shape of fault-karst reservoir,using amplitude change rate and chaotic phase attributes to classify and predict internal reservoirs in fault zone,and using multi-attribute fusion to characterize and describe fault-karst reservoirs.The technologies of fault-karst reservoir identification and trap description have been established.The application of these technologies has guided the deployment of several wells in the Shunbei area,which have achieved major breakthroughs in oil and gas discovery.The penetration rate of reservoirs is 84%,which proves the validity and applicability of the technologies.It provides a solution and technical reference for identification and description of fault-karst reservoirs in the Shunbei Oil and Gas field as well as other areas,and is of great significance for exploration and development of fault-karst reservoirs in ultra-deep formations in the Shunbei Oilfield.