透镜体油气成藏机理研究现状与发展趋势

随着石油勘探研究的不断深入,砂岩透镜体油藏日益受到重视。国内外学者提出了多种成藏机制,包括未知重力运动机制作用下,少数流体分子的个别特性控制透镜状砂岩油藏聚集;毛细管力作用下油气替换透镜体中的孔隙水;烃浓度差是油气向砂体运移的主要动力;流体压力差使油气首先沿着裂隙向砂岩透镜体中运移、聚集而成藏;差异突破作用使砂岩透镜体成藏等。成藏动力学、成藏模式及主控因素、定量研究、物理模拟实验、数值模拟及分布预测等将是今后发展的方向。     

西湖凹陷西斜坡平湖组储层特征及致密化过程分析

综合应用铸体薄片、扫描电镜、阴极发光、恒速压汞、流体包裹体和X衍射等分析技术,对储层岩石学、孔喉结构和成岩作用类型及特征进行深入研究,探讨储层致密化过程和物性演化。结果表明：平湖组储层砂岩类型主要为长石岩屑质石英砂岩,以细—中粒结构为主,分选性中到好;孔隙类型以溶蚀粒间孔为主,孔隙半径主要集中于130～190 μm,喉道半径主要集中于0.2～10 μm;埋藏压实是导致平湖组储层低渗-特低渗的主因,埋深、粒度及泥质决定了压实作用的强弱,而后期次生溶蚀及胶结作用的差异加剧了储层的非均值性。中成岩A期平湖组储层次生溶蚀规模受限于流体环境,细粒沉积不利于后期溶蚀是造成储层致密化的主因;进入中成岩B期,成岩环境呈碱性且逐渐封闭,大量含铁碳酸盐、呈丝状或弯曲片状伊利石等富集堵塞喉道,致使储层大规模致密。     

渤海古近系东营组三角洲相油田地质特征研究

渤海古近系东营组三角洲相油田是渤海油田的主力含油层系.从构造、储层与沉积、流体和油藏等方面对渤海海域东营组三角洲相油田地质特征进行了研究,按河流三角洲和辫状河三角洲相砂岩油藏两种沉积相类型分别对储层分布特征进行了描述.在此基础上探讨了此类油田的流体分布特点和油藏模式,并认为渤海东营组三角洲相油田以中到大型为主,储层岩性大都属于高孔高渗的疏松砂岩,储层具有分布较稳定、油层厚和物性好等特点,原油以普通稠油为主,其次是中、低黏油.     

琼东南盆地北礁地区梅山组丘形反射特征

目前琼东南盆地北礁凹陷中中新统梅山组顶部丘形反射引起广泛关注,但对其成因有不同认识。本文通过高精度二维、三维地震、钻井资料,研究丘形反射的特征。研究表明北礁地区梅山组顶部发育近东西向展布的长条形丘体,丘间为水道,丘内为中-弱振幅的地震反射,与西南部强振幅水道砂岩形成鲜明的对比,波阻抗反演揭示丘内为低波阻抗,属泥岩范畴。梅山组塑性丘内地层发生重力扩展,在其上覆的脆性地层（强振幅砂岩和弱振幅泥岩）发育多边形断层,反推出梅山组形成于深水环境,丘为泥丘,沉积环境分析也认为北礁凹陷中中新世为半深海沉积,梅山组的丘-谷分别对应上覆地层的谷-丘,认为是底流剥蚀/沉积成因。本文的研究对南海北部丘形反射的认识有重要意义,并可降低油气探勘风险。     

Multiple controls on the paleoenvironment of the Early Cambrian marine black shales in the Sichuan Basin,SW China: Geochemical and organic carbon isotopic evidence

In order to understand the paleoenvironment of the Early Cambrian black shale deposition in the western part of the Yangtze Block, geochemical and organic carbon isotopic studies have been performed on two wells that have drilled through the Qiongzhusi Formation in the central and southeastern parts of Sichuan Basin. It shows that the lowest part of the Qiongzhusi Formation has high TOC abundance, while the middle and upper parts display relative low TOC content. Redox-sensitive element (Mo) and trace elemental redox indices (e.g., Ni/Co, V/Cr, U/Th and V/(V + Ni)) suggest that the high-TOC layers were deposited under anoxic conditions, whereas the low-TOC layers under relatively dysoxic/oxic conditions. The relationship of the enrichment factors of Mo and U further shows a transition from suboxic low-TOC layers to euxinic high-TOC layers. On the basis of the Mo-TOC relationship, the Qiongzhusi Formation black shales were deposited in a basin under moderately restricted conditions. Organic carbon isotopes display temporal variations in the Qiongzhusi Formation, with a positive excursion of δ¹³C_org values in the lower part and a continuous positive shift in the middle and upper parts. All these geochemical and isotopic criteria indicate a paleoenvironmental change from bottom anoxic to middle and upper dysoxic/oxic conditions for the Qiongzhusi Formation black shales. The correlation of organic carbon isotopic data for the Lower Cambrian black shales in different regions of the Yangtze Block shows consistent positive excursion of δ¹³C_org values in the lower part for each section. This excursion can be ascribed to the widespread Early Cambrian transgression in the Yangtze Block, under which black shales were deposited.     

大川中地区须家河组二、四段地震相与沉积相研究

四川盆地上三叠统须家河组油气勘探开始于20世纪40年代,其中须二段、须四段是主要探目的层段,也是盆地周边地区寻找新气源最有利层位之一。依据地震地层学方法和理论,结合钻井与测井资料,将大川中地区须家河组划分成7个地震层序边界,分别为SB1—SB7,与之对应6个最大湖泛面,分别为MFS1—MFS6,并对层序界面的地震反射特征进行了总结。利用地震反射内部结构、外部形态和反射波终止类型,在大川中地区须家河组须二段与四段内共识别出平行—亚平行、前积、丘状、透镜状及发散状地震反射特征等5种地震相,并对18条二维地震测线进行了剖面地震相的综合解释,编制了须二段与四段的地震相平面分布图。通过地震相与沉积相的转换,分别划分出冲积扇、扇三角洲、辫状河三角洲以及湖泊等沉积体系,编制了大川中地区须家河组二段与四段沉积相平面图,对大川中地区须家河组构造格局的演化规律进行了分析。     

Marine hydrocarbon source rocks of the Upper Permian Longtan Formation and their contribution to gas accumulation in the northeastern Sichuan Basin,southwest China

Identification of the main hydrocarbon source rocks of the large Puguang gas field (northeastern Sichuan Basin, southwest China) has been the subject of much discussion in recent years. A key aspect has been the lack of a comprehensive understanding of the development of hydrocarbon source rocks of the Upper Permian Longtan Formation, which had been thought to contain mainly coal seams and thick carbonate layers. In this paper, based on geological data from more than ten wells and outcrops and their related mineralogy and geochemistry, we investigated the depositional environment and main factors controlling organic matter enrichment in the Longtan Formation. We propose a model which combines information on the geological environment and biological changes over time. In the model, organic matter from prolific phytoplankton blooms was deposited in quiescent platform interior sags with rising sea-levels. During the Longtan period, the area from Bazhong to Dazhou was a platform interior sag with relatively deep water and a closed environment, which was controlled by multiple factors including syngenetic fault settling, isolation of submarine uplifts and rising sea-levels leading to water column stratification. Although the bottom water was anoxic, the phytoplankton were able to bloom in the well-lit upper euphotic zone thus giving rise to a set of sapropelic black shales and marlstones containing mostly algal organic matter with minor terrestrial contributions. As a consequence, these rocks have a high hydrocarbon generation potentials and can be classified as high-quality source rocks. The area from Bazhong to Dazhou is a center of hydrocarbon generation, being the main source of reservoired paleo-oils and presently discovered as pyrobitumen in the Puguang gas field. The identification of these source rocks is very important to guide future petroleum exploration in the northeastern Sichuan Basin.     

珠江口盆地西江凹陷南部文昌组层序地层及沉积体系研究

珠江口盆地西江凹陷南部包括两个相邻洼陷：西江36洼和番禺4洼,钻探结果却揭示了截然不同的油气勘探前景,其中,番禺4洼探明储量已过亿吨,而西江36洼却未有商业发现,导致勘探上对西江36洼烃源潜力有所顾虑。为了揭示这种差异油气地质条件产生的原因,亟待开展两个洼陷的对比研究。以主要烃源层系文昌组为切入点,通过开展精细的层序-沉积研究,进一步系统评估西江36洼烃源潜力。依据地震、钻井及分析化验等资料,在西江36洼与番禺4洼文昌组共识别了6个三级层序。西江36洼和番禺4洼文昌组发育扇三角洲、辫状河三角洲、湖底扇及湖泊沉积等沉积相类型,垂向上沉积相带具有旋回特征。伴随裂陷不同阶段和边界断层活动差异,陡坡带和缓坡带三角洲沉积体系规模呈现差异演化特征,而湖盆和半深湖-深湖相规模总体呈现出先增大后减小的规律。沉积相带在横向上也具有明显的迁移特征,表现为文六段时期先在西江36洼开始沉积,文五段开始再扩展到番禺4洼,同时文一段时期西江36洼湖盆已经消失,只在番禺4洼沉积充填。进一步对比两个洼陷各三级层序反映优质烃源岩条件的半深湖-深湖规模及物源供给量,结果显示在文六段至文四段时期两个洼陷烃源条件基本一致。鉴于该层段作为番禺4洼的主力源岩,其巨大的生烃潜力已经被勘探所证实,因此认为不能低估具有相似烃源条件的西江36洼生烃潜力。     

西湖凹陷Y构造花港组气藏特征及成藏主控因素

以常规和非常规油气成藏理论为指导,结合储层、流体等测试分析结果,开展西湖凹陷Y构造花港组气藏特征及成藏主控因素研究。结果表明：① 花港组垂向上符合中下部致密砂岩气、上部常规天然气藏的分布序列;② 常规气藏气水关系正常,受断盖配置对沿断裂运移油气的封闭作用和断层侧向封堵能力影响,油气主要在区域盖层之下的断背斜顶部富集;③ 致密气藏具叠覆跨越源储组合关系,含气饱和度低,无明显气水界面,属先致密后成藏类型,不同部位含气性受构造幅度和储层物性共同控制。本次研究丰富和完善了西湖凹陷常规-非常规天然气序列成藏规律,并为致密砂岩气的勘探提供理论指导。     

珠江口盆地番禺4洼文昌组基于层序地层格架约束下的优质烃源岩预测

珠江口盆地番禺4洼“小而肥”,目前的探明石油地质储量已超出早期估算的地质资源量,早期对烃源岩的认识不足可能是其主要原因,尤其是对优质烃源岩的分布范围仍缺少精确刻画,在很大程度上限制了对该洼陷勘探潜力的认知。以该难点问题为切入点,利用最新钻井和地震资料,采取层序地层学开展了番禺4洼烃源岩的预测工作。通过地震资料上识别的各种反射特征,结合区内已有钻井资料识别的旋回特征,将番禺4洼文昌组划分5个三级层序,进而建立了等时地层格架。在此基础上,综合运用地震沉积学最新技术手段,精细揭示了番禺4洼文昌组文三段优质烃源岩的分布范围。研究结果表明,番禺4洼优质烃源岩分布面积较为广泛,尤其在北次洼和西次洼,优质源岩面积均超过了以往预期。这一研究成果对本区和珠江口盆地油气勘探具有一定指导意义。