【作者】 高鹏鹏；

【导师】 孙卫；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 近年来,随着技术手段更新和勘探领域扩大,陆续在延长组深层发现了一批油藏,其中最具代表性的是长庆油田在盆地西南部西峰地区长8水下扇发现多达4亿吨整装优质储量,在安塞地区的长10钻探了高52井高产油流井(日产油64.7t/d)；延长油田在吴起-志丹地区在长8、长9、长10油层组也取得了良好的勘探效果。本文以延长组深层油层组为研究对象,在收集大量地质、钻探等资料的基础上,以石油地质学、成藏地质学理论为指导,重点分析了延长组深层沉积类型、储层特征、烃源岩特征、油气运聚动力及成藏组合,揭示了成藏主控因素,总结成藏规律。主要在以下几个方面取得了新的认识：1.通过地层对比,搞清了研究区地层展布及变化规律：长101亚油层中上部地层厚度变化不大,平均厚度在50-70m之间,西北部地层厚度相对较大,由北部及中部向西部及东南部逐渐减小；长9油层组厚度变化平均厚度在90-130m之间,地层厚度及电性特征由北西向南东方向变化较明显,顶部“李家畔”页岩主要发育于研究区东部；长8油层组厚度平均厚度在50-100m之间,地层厚度由北向南逐渐增厚,由东向西逐渐减薄的趋势；长7油层组厚度变化平均厚度在70m-110m之间,地层厚度由北向南逐渐增厚,由西向东呈先减薄后又逐渐增厚。2.延长组深层主要发育浅水三角洲沉积,仅长7发育有深湖相和湖底扇沉积；浅水三角洲砂体沉积具有受“湖岸线控砂”的规律。含油砂体主要分布在三角洲前缘亚相的水下分流河道及河口坝微相中。3.延长组深层储层主要以长石岩屑砂岩为主,整体分选好、磨圆较差；除长101-2浊沸石胶结物含量相对均比较高以外,其它层主要以方解石胶结物为主；孔隙类型主要以原生粒间孔为主,孔隙结构类型主要为小孔-微喉型和中孔-微细喉型；沉积微相和成岩作用是控制和影响研究区储层发育和展布的主要因素。依据试油层位声波—电阻关系,基本确定了不同区域延长组深层油层的电性标准。4.明确了延长组深层共发育有长7、长9、长10三套烃源岩,其中长7为主要烃源岩,主要位于研究区西部及南部；长9次要烃源岩主要位于研究区的东南部；长10次要烃源岩主要位于研究区中西部；其中,长7烃源岩干酪根多为Ⅰ型,高成熟度,属好烃源岩；长9、长10干酪根多为Ⅱ型,高成熟度,为较好烃源岩。从烃源岩来源分析,延长组深层地层存在单向源供成藏、双向源供成藏两种成藏类型；从源储关系看,具有上生下储和下生上储两种成藏组合。5.揭示了长7、长9过剩压力及邻层过剩压力差是石油运移的主要动力,平面上延长组深层各层过剩压力相对低值区是油气运移的有利指向,纵向上延长组深层各层源储过剩压力差低值背景下的相对高值区是油气聚集的主要场所。6.认为延长组深层油藏主控因素存在差异,可分为过剩压力主控油藏、古构造主控油藏以及过剩压力与古构造共控油藏三类；认为延长组深层具有“源控区、相控带、势控向、压控位”的油气聚集规律,即深部油藏多分布于近烃源区,发育在三角洲前缘和重力流沉积相带,过剩压差低值区为油气运聚的有利地区。7.综合运用砂厚等值线与烃源岩厚度叠合图,结合过剩压力、录井、电测解释和试油成果建立了油气有利富集预测区分类标准并预测了有利区,其中Ⅰ类有利区3个、Ⅱ类有利区4个,并进行有利区储量计算,结果表明延长组深层勘探潜力巨大。更多还原

【Abstract】 In recent years, with the advance of technical means and expansion of the exploration field, groups of reservoirs were found in the deep zones of Upper Triassic Yanchang formation. One of the most representatives is Xifeng oilfield found in southeastern of Ordos Basin with high-quality reserves of400million tons in underwater fan, and Well Gao-52was drilled in Ansai with daily output of64.7t/d. The good results were also made in formations of Chang8,Chang9and Chang10of Wuqi-Zhidan area by YanChang Oilfield. In this paper, the oil reservoirs in lower part of Yanchang formation was studied to analyze the deposition type, reservoir characteristics, feature of hydrocarbon source rocks, force of petroleum migration-accumulation and accumulation combinations, to reveal the main controlling factors of accumulation, and to summarize the rules of accumulation.The new views are as follows:1. Through stratigraphic correlation,the strata distrubution and variation rules of the study ares was knew.That is, the stratigraphic thickness of Chang101remain stable with average thickness50-70m,relativly large in northwest; the average thickness of Chang9is90-130m with the Lijiaban shales developedn in eastern part; the average thickness of Chang8is50-100m,thickening gradually from north to south and thinning from east to west; the average thickness of Chang7is70-110m, thickening gradually from north to south and thinning from west to east,then thickening again.2. The shallow-water delta was developed in the lower part of Yanchang formation, the deep lake&sublacustrine fan only found in Chang7, the sandbody in which was controlled by swing of the lake shourline and that were mainly distributed in underwater distributary channel and mouth bar microfacies of the delta front subfacies.3. The feldspar sand was mainly developed with good separation and less rounded; dominated by calcite cements except lomontite cement in Chang101-2. The type of pores is mainly primary pore and its structure is small pore with thin throat, or medium pore with thin throat. Sedimentary micro-facies and lithogenesis are the primary factors controlling and influencing the formation development and spreading of target region. According to Sonic-resistance relationship, the electrical standard of reservoir in the lower part of Yanchang formation in different regions. 4. It is presented that three sets of hydrocarbon source rocks (Chang7, Chang9and Chang10, among which the Chang7as the main hydrocarbon source rocks, mainly located in the western and southern parts of the study area; the secondary one of Chang9located in the southeastern region and the secondary one of Chang10mainly located in the central and western regions of the study area. The organic matters of Chang7source rock is I type with high maturity which belongs to excellent hydrocarbon, and the type of Chang9and Chang10is Ⅱ type, high maturity, belongs to better hydrocarbon. The source of reservoir is one-way or two-way direction, showing the accumulation model "injection migration"or"lower-generation and upper storage".5. It was showed that the overpressure and the overpressure gap of adjacent layers was the main force of oil migration. The orientation of migration is the relatively low-value area on the plane and relatively high value in the background of low-gap is the residence of hydrocarbon accumulation.6. The factors of accumulation in lower part of Yanchang formation are different, which could be divided into three types:controlling reservoir, paleostructure controlling reservoir and reservoir controlled by pressure&paleostructure. It is shown that the reservoir distributed in where hydrocarbon source developed, the delta-front and gravity-flow sediment are the main areas for the ultra-low-permeability reservoirs and the places of low-overpressure are the preferential places for hydrocarbon migration&accumulation.7. Integrated using of sand body thickness contours with hydrocarbon source rock thickness congruency map, combined with overpressure, logging and testing, the rich areas of accumulation were indicated, among which, the reserves were caculated, showing great potential of deep zones of Yanchang formation.更多还原