Lacustrine shale oiliness influenced by diabase intrusions in the Paleogene Funing Formation,Subei Basin,China

The research on the correlation between hydrocarbon accumulations and magmatic activities has always attracted aroused much wide attention.Existing research has primarily the hydrocarbon generations capability of source rocks and the quality of reservoirs by diabase intrusions.whereas,rare systematic research has been conducted on the oiliness and enrichment mechanism.To be specific,the diabase intrusive zone,the contact metamorphic zone and the normal shale zone of the Funing Formation in the Gaoyou Sag,Subei Basin were taken as the object of this study.Moreover,in this study,the hydrocarbon generation quality,reservoir quality,and oil-bearing quality of diabase-metamorphic zone-normal shale were evaluated using X-ray diffractions,argon ion polishing-field emission scanning electron microscope,energy spectrum,rock slice/light-sheet microscopic observations,organic geochemical tests,N_(2) gas adsorption and 2D NMR tests.The results indicated that the intrusive zone,the metamorphic zone,and the normal zone were formed in order by the degree of effect of diabase intrusions.Secondly,the oil content of different parts exhibited significant heterogeneity due to the baking effect of diabase,and the metamorphic zone had the significantly better oil-bearing nature than the intrusive zone.Lastly,a distribution model was proposed for the diabase intrusive zone-metamorphic zone-normal surrounding rock zone.

苏北盆地溱潼凹陷沙垛1井侵入岩岩石学特征及其储集性与含油性研究

火成岩油气藏逐渐成为重要的油气藏类型,但火成岩储层非均质性很强,储集性能变化很大,储层成因机制研究非常薄弱,成为制约火成岩储层评价的主要瓶颈。以苏北盆地溱潼凹陷古近系阜宁组二段侵入岩为研究对象,通过系统的岩心观察、薄片鉴定、电子探针分析测试和测井解释等,剖析了溱潼凹陷沙垛1井阜二段侵入岩岩性、岩相特征、储层特征和储层发育主控因素。结果表明:该区侵入岩的岩性纵向变化显著,由多期侵入岩叠加组成,顶部为辉绿岩,中部为辉石二长岩,下部为橄榄辉长岩;孔隙发育程度不均一,辉绿岩和辉石二长岩孔隙发育程度低,而橄榄辉长岩孔隙发育程度较高;由于多期侵入作用的叠加以及热液蚀变的改造,发育了较好的储集空间。孔隙类型主要为溶蚀孔和构造裂缝,还发育收缩裂缝。影响储层物性的主要因素是岩性和热液流体活动,其中橄榄辉长岩中辉石等暗色矿物最易蚀变,溶蚀孔发育程度高;此外,区域性的断裂构造在许多致密的火成岩中产生了大量的构造裂缝,有效沟通了侵入岩储层的孔缝系统,且为后期的溶蚀作用提供了岩浆热液流动的通道。沙垛1井钻遇的侵入岩总体上含油性差,下部侵入岩层中可见零星荧光显示,上部侵入岩层中基本不含油。

云南富宁地区晚三叠世基性侵入岩岩石学特征及其构造意义

通过对云南富宁地区厘定的一套基性侵入岩地质学、岩石学、地球化学分析。结果表明:该基性侵入岩主要由辉长辉绿岩、辉绿岩等组成,主要矿物由斜长石、辉石组成,局部可见微弱热液蚀变发育;SiO2含量43.92%~56.02%,全碱alk=3.12%~7.64%,具有富铝镁钙、低钛铁钾特点,属亚碱性系列;岩石呈现轻稀土富集、重稀土亏损的弱分异右倾式稀土元素配分模式特征,LREE/HREE=1.81~3.77,(La/Yb)N=4.33~11.89,(La/Lu)N=4.35~12.53,(Ce/Yb)N=5.43~49.87,(Gd/Yb)N=1.3~2.65,La/Sm=3.8~5.5,(La/Sm)N=2.07~3.46;微量元素表现为K、Sr、Nb、P、Zr、Ti存在不同程度富集、亏损,显示具同化混染作用岩浆特征;构造判别图显示出统一的板内构造背景,其时代可能为晚三叠世。

高邮凹陷北斜坡辉绿岩及其接触带储层发育特征与有利油气藏条件

理论研究与勘探实践表明岩浆侵入作用能够形成侵入岩—外变质带油气储层。以高邮凹陷北斜坡地区阜宁组为研究层位,根据岩心、薄片、分析测试等资料,重点研究了高邮凹陷北斜坡地区辉绿岩及其接触带的储层发育特征,并从烃源岩和成藏条件分析了研究区油气藏形成的有利条件,讨论了岩浆侵入活动对油气成藏造成不利影响的可能性。辉绿岩及其外变质带(接触带泥岩和砂岩)均可作为储层,辉绿岩储集空间包括原始气孔、冷凝裂缝、溶蚀孔隙、微孔、收缩微缝及构造裂缝;接触带泥岩储集空间包括构造裂缝、热液微裂缝、收缩缝、解理缝、晶间微孔和微溶孔;接触带砂岩储集空间包括原生粒间孔、粒间溶孔、粒内溶孔、铸模孔、超大孔及微溶孔。辉绿岩和接触带泥岩整体物性较差,非均质性强,发育的裂缝系统是储层性能改善的重要因素。相对于未受辉绿岩影响的正常储层而言,接触带砂岩的储集性能变差。研究区地球化学特征和油气藏分布特征等证据表明辉绿岩侵入降低了烃源岩生烃门限,加速了有机质向油气的转化,为辉绿岩及变质带储层提供了油气来源。研究区有利成藏条件主要包括:近距离油源供给、辉绿岩侵入形成运移通道、油气运移与圈闭形成良好时空配置、较大规模的辉绿岩及变质带和良好的封闭遮挡条件。