海安凹陷新街断裂带成藏条件及成藏模式

Reservoir-forming conditions and models of Xinjie fault zone in Haian Sag

利用新街次凹多口井岩心、测井及分析测试等资料,明确该区烃源岩条件、沉积特征及砂体展布;利用新街北三维地震资料,分析了新街断裂带构造特征及其控藏因素。研究表明:该区发育泰州组二段和阜宁组二段两套烃源岩,其中泰二段烃源岩分布范围广,成熟度高;阜二段成熟烃源岩围绕新街断裂带下降盘深凹中心分布,分布范围有限。泰州组一段可识别出三类沉积亚相和五类沉积微相类型,以水下分流河道砂体为主;阜宁组三段位于三角洲前缘亚相的前端位置,主要发育河口坝砂体;三垛组一段为河道沉积,底部沉积了一套典型河道砂体。研究区发育三套生储盖组合,其中泰州组生储盖组合为主要勘探目的层。分析认为新街断层是由两条边界大断层组成,具有左行右阶雁列展布、分段发育的特点,控制了圈闭的形成和油气运聚,据此建立了新街断裂带陡坡带成藏模式。

According to the data of core, well logging and experimental test of several wells in Xinjie Subsag,the conditions of source rocks, sedimentary characteristics and sand-body distribution in this area were clarified. Based on the 3-D seismic data in the north of Xinjie, the structural characteristics of the Xinjie fault zone and its controlling factors were analyzed. The results show that there are two source rock of K 2 t 2 and E 1 f 2,in which K 2 t 2 source rock has a wide range of distribution and high maturity,and E 1 f 2 source rock is distributed around the center of the the hanging wall area of Xinjie fracture zone with limited distribution. Three types of subfacies and five types of microfacies can be identified in K 2 t 1 of the study area, where subaquatic distributary channel is major reservoir .The E 1 f 3 is located at the front of the delta front, where the mouth bar sand is mainly developed. The E 2 s 1 is channel deposit, where a set of typical channel sand is deposited at the bottom.Three sets of source reservoir caprock assemblages are developed in the study area, of which K 2 t is the main exploration target. The analyses show that the Xinjie fault is composed of two large boundary faults, with characteristics of sinistral right step distribution and segmental development, which controls the formation of traps and hydrocarbon migration.Based on this, the pooling pattern of the steep slope belt of Xinjie fracture zone has been established.