油源断裂转换带优势输导油气条件研究

In recent years, more and more explorations have proved that:oil and gas is not distributed around the whole source fault while distributed at the bending twist point of a source fault、intersection zones and the transfer zones which are developed at the end of a fault. In order to find out the advantages of oil and gas conduiting in the transfer zones of a source fault and determine the advantage conduiting pathway, we take middle and upper layers in Bohai Gulf Basin Nanpu sag as an example, based on the identification of the source faults, by recognizing the current transfer zones of faults and recovering the ancient transfer zones which were developed at pool-forming period, we pick out the transfer zones of source faults which had been developed long before oil and gas reservoir formed, and is the control transfer zones of the reservoir at the same time, Combine with the provenance analysis to determine the method of sand body distribution, establish the geological model in the region of interest, based on rock core fracture analysis， FMI imaging well logging data and stress field ，lithology parameter test, and then predict simulatly stress distribution of the transfer zones in source faults and the fractures' feature by the application of Traptest5.4 software system. Determining the form of faults' surfaces and the distribution of fluid potential, building the standard of superiority in oil gas conducting in the source faults, according to this standard can we predict the best position of conducting oil and gas in source faults, by this way, we can select the best position of the reservoir forming in the exploratory area of middle and upper layers in Nanpu sag.

近年来，越来越多的勘探证实油气并非围绕整条油源断裂分布，而往往集中分布于油源断裂弯曲转折端、断裂交汇区及断裂末端等转换带位置，为了查明油源断裂转换带对油气输导的优势条件并确定优势输导通道，以渤海湾盆地南堡凹陷中浅层为例，在厘定油源断裂的基础上，通过现今断裂转换带识别及成藏期古转换带恢复，优选出在成藏期之前形成并控藏的油源断裂转换带，结合物源分析确定砂体展布规律，建立研究区地质模型，其次，在岩心裂缝分析、FMI成像测井资料及应力场方向、岩石学参数测试的基础上应用Traptest5.4软件系统对南堡凹陷大量油源断裂转换带应力分布及裂缝特征进行模拟预测，最后，确定转换带断面形态和流体势分布。综合这些参数建立油源断裂转换带优势输导条件标准，据此标准预测南堡凹陷中浅层待评价探区油源断裂优势输导油气部位，优选成藏目标。

油源断裂转换带优势输导油气条件研究是一项多方面综合性研究课题，目前有关其研究多以断裂发育特征和转换带发育特征研究为基础，然而油源断裂转换带在输导油气过程中涉及的一些综合科学问题尚未完全阐明。本课题采用地质综合分析的方法，开展油源断裂转换带优势输导油气条件研究，内容包括结合断裂发育特征对油源断裂进行厘定，进而开展油源断裂转换带识别及古恢复。通过研究油源断裂转换带控制砂体、古油气势能差及裂缝分布特征，研究其垂向和侧向优势输导油气条件，并结合地层倾向及断裂活动强度分析油源断裂转换带对油气富集的控制作用。本项目经过4年基础攻关研究，取得了一些创新性成果，包括：1、油源断裂软连接和硬连接转换带均是其侧向输导油气的有利部位，但只有油源断裂硬连接转换带才是其垂向输导油气的有利部位；2、油源断裂转换带处砂体、裂缝发育，且存在油气势能差，均有利于侧向输导油气，也有利于硬连接转换带垂向输导油气；3、油气成藏期活动强度大的顺向型油源断裂上盘硬连接转换带部位是油气富集的有利部位。本项目对于研究油源断裂及转换带输导油气作用，加强油源断裂转换带优势输导油气条件的认识，促进断裂控藏理论的丰富完善均具有重要意义，并为进一步优选油气成藏目标提供理论依据。