盐家地区砂砾岩油气成藏

GLUTENITE RESERVOIR FORMING OF YANJIA AREA

盐家地区具有陆相断陷盆地陡坡带的典型构造特征，具有良好的成藏条件，广泛发育了各种类型的砂砾岩岩性油藏。由于砂砾岩沉积和成藏的复杂性、隐蔽性，导致砂砾岩油藏预测和描述存在着很大的困难。针对盐家地区砂砾岩体油气勘探现状及存在的主要问题，在地质、地震、测井、岩心、地球化学资料分析研究的基础上，分析了研究区的沉积类型，特别对沙四段的沉积类型进行了深入研究，沙三段和沙四段主要包括河流三角洲沉积体系、近岸水下扇、远岸深水浊积扇、扇三角洲系列，各层段形成了多种沉积体系的纵横向展布序列。对该区沙三段、沙四段砂砾岩体储层分布及油气成藏特点分析，指出该区油气运移以顺层运移为主，作短距离垂向运移，以纵向上多层段阶梯状含油的多套含油系统为特点。对砂砾岩体的形态、储层和含油性开展描述和预测，建立砂砾岩体识别和描述技术，建立盐家地区砂砾岩体成藏模式，并进行砂砾岩体油藏分布预测，指出滑塌砂砾岩和深层砂砾岩是近期勘探的重点，建议下步勘探目标为东辛北带永安地区及青南洼陷北部陡坡带莱78地区。

Yanjia area has typical structural features of abrupt slope of continental rift basin and has favorable res- ervoir forming condition with several types of widely developed glutenite lithologic reservoirs. Being complex and subtle sedimentation and reservoir forming, predication and description of glutenite reservoir has much difficulty. Aiming at hydrocarbon exploration situation and some problems of glutentie reservoirs in Yanjia area, and based on geologic, seismic, well logging, core and geochemistry data study, sedimentary types are analyzed especially for Sha IV Member. Results show that, Sha III Member and Sha IV Member include fluvial-delta sedimentary system, coastal subsea fan, offshore deep sea turbidite fan and fan delta system. Each interval＇forms vertical and lateral se- quence of several sedimentary systems. Analysis on glutenite reservoir distribution and hydrocarbon reservoir form- ing characteristics in Sha III Member and Sha IV Member indicates that oil and gas migration is dominated by bed- ding migration, with short-distance vertical migration, and with characteristics of vertically several sets of multi-in- terval step-shaped oil bearing systems. Glutenite body shape, reservoir and oil bearing property are described and predicted. Identification and description technique for glutenite body is established. Reservoir forming pattern of Yanjia area is established, and glutenite reservoir distribution is predicated. It is indicated that slump glutenite and deep glutenite are main recent exploration target, and it is proposed that Yongan area in northern Dongxin and Lai 78 area in northern abrupt slope belt of Qingnan Sag are next step exploration target areas.