川东北元坝地区长兴组台缘礁滩体系内幕构成及时空配置

借助层序地层学技术、地震特征识别方法以及地震反演手段,对川东北元坝地区上二叠统长兴组台缘生物礁滩体系的发育特征进行了详细研究,发现长兴组可分为2个三级层序,其中下部为成滩层序,上部为成礁层序。生物礁主要发育于上部层序的高位体系域内。在地震剖面和反演剖面上揭示出5个成礁旋回,其中前2期生物礁为退积式生长,后3期生物礁为进积式生长。波阻抗反演平面图也显示了生物礁的礁前滩和礁后潍的相带分类,表明台地内的台内生屑滩主要发育于台地的南部。

礁滩型气藏与燕山、喜山期构造体系的关系

四川盆地川东北地区上二叠统长兴组生物礁、滩型气藏和下三叠统飞仙关组鲕粒生物滩型气藏勘探在普光、毛坝取得重大突破之后,很多研究者从沉积相研究出发,都认为这些礁滩是沿广旺海槽、城口—鄂西海槽以及梁平—开江海槽坡折带分布的丘形体,油气富集与海槽相关。然而,叠加上覆燕山、喜山期的构造形迹分析则发现,这些礁滩型气藏在油气成藏运移过程中还与扭动构造体系相关,特别是与各类扭动构造体系的砥柱密切相关。据此观点进行研究进而预测:巴中、仪陇莲花状构造,中台山、绵阳旋扭构造体系的砥柱与下伏地层地震剖面丘形体叠置处有望获得重大的礁滩型油气藏发现。

Combination Patterns and Depositional Characteristics of Ordovician Carbonate Banks in the Western Tarim Basin,China

The combination patterns and depositional characteristics of the carbonate banks are investigated based on outcrop sections, thin sections, and carbon isotopes of Ordovician in the western Tarim Basin, China. Four carbonate bank combination patterns are deposited in the Ordovician, western Tarim Basin, including： Reef-Bank Complex （RBC）, Algae-Reef-Bank Interbed （ARBI）, Thick-Layer Cake Aggradation Bank （TLCAB）, and Thin-Layer Cake Retrogradation Bank （TLCRB）. All combination patterns show clear periods vertically. The RBC is mainly composed of reefs and bioclastic banks, and the dimension of the RBC depends on the scale of the reefs. Bioclastic banks deposits surround the reefs. The range of the ARBI is determined by the scale of algae-reefs, algae peloid dolomite microfacies and algal dolomite microfacies deposit alternating vertically. TLCAB and TLCRB are deposited as layer-cakes stacking in cycles and extending widely with cross bedding developed. The grains of TLCAB and TLCRB are diverse and multi-source. With the impacting of relative sea level change, biological development and geomorphology, the ARBI, TLCAB or TLCRB, RBC are successively developed from the Lower Ordovician Penglaiba Formation to the Middle Ordovician Yijianfang Formation. The depositional environment analysis of Ordovician indicates that the RBC and ARBI can form effective oil and gas reservoirs, and the TLCAB and TLCRB have the potential to form the huge scale oil and gas reservoirs and to be the crucial targets of exploration for the Ordovician carbonate banks in the future.

巴西桑托斯盆地盐下碳酸盐岩油藏硅化作用成因及其对储层的影响

巴西桑托斯盆地M油田盐下巨厚湖相碳酸盐岩储层发育硅化作用,目前尚未有相关研究探讨其成因机制。为此,综合利用岩心、薄片、流体包裹体测试和X射线荧光分析等资料,对M油田不同硅化作用特征开展成因探讨,并在此基础上分析其对储层的影响。研究结果表明:硅化作用在M油田较为普遍,超过一半样品受硅化作用影响,但仅有17%的样品属于中-强硅化作用。硅化作用成因类型包括3种,分别为沉积型、早期成岩型和热液型。沉积型和早期成岩型硅化作用对储层物性影响有限。综合证据显示,强热液硅化层段与侵入岩空间分布关系密切;同时其主要氧化物含量介于侵入岩和碳酸盐岩围岩之间,呈二者混染特征,且流体包裹体均一温度较高(87~193℃),证明热液硅化作用为岩浆期后热液所致。岩浆期后热液倾向于沿碳酸盐岩地层内部的断层、裂缝、不整合面等构造薄弱带以及与这些薄弱带相连通的高基质孔隙带流动,使储层发生强烈硅化作用。当硅质含量大于10%,对储层物性产生较大影响。

南海西科1井上新世以来礁滩体系内部构成及其沉积模式

通过对西科1井薄片进行鉴定,对上新世以来莺歌海组和乐东组礁滩沉积体系的古生物种类、岩石微相类型及成因相类型进行了系统剖析.研究表明:乐东组造礁生物以珊瑚和红藻为主,莺歌海组以红藻为主.附礁生物主要包括有孔虫、棘皮类和绿藻,其中有孔虫为最重要的附礁生物,绿藻只在乐东组的个别层段极发育.根据生物种类及含量、泥晶、亮晶及粒间孔含量的大小关系,识别出10种岩石微相.在此基础上,将礁滩体系划分为生物礁、生屑滩和泻湖3种成因相组合.生物礁包括礁基、礁核和礁盖3种成因相,其中礁盖可见显著的溶蚀现象,形成粒内溶孔、铸模孔等次生孔隙.在研究井段仅发育礁后滩,靠近礁核的礁后内侧滩生屑及粒间孔含量高,而泥晶少;靠近泻湖的礁后外侧滩则情况相反.泻湖主要沉积大量灰泥,生屑含量少.礁滩体系仅在海侵体系域和高位体系域发育,各成因相之间具有相对固定的成因相垂向叠置关系.海侵体系域主要发育退积型成因相组合序列,准层序以代表海泛面的泥晶含量较高的成因相结束;高位体系域主要发育进积型成因相组合序列,多以对应暴露面的礁盖结束.

Discovery of Yanting-Tongnan Trough of Late Permian in Sichuan Basin and Its Significance

ABSTRACT： Reef-bank of Sichuan （四川） basin have been explored along the platform margin belt on both sides of the Kaijiang （开江）-Liangping （梁平） trough for a long time. Correspondingly, a series of major breakthroughs have been obtained and a number of large oil and gas fields have been found. After the breakthroughs of Kaijiang-Liangping trough, how reef-bank exploration will proceed？ Is there another ＂Kaijiang-Liangping trough＂ in Sichuan basin？ Previous research shows that Sichuan basin underwent intracratonic rift and basement fault activities in Late Permian, developing a paleogeography framework of ＂three uplifts and three depressions＂ under the background of the regional large ramp, including Exi （鄂西）-Chengkou （城口） trough, Kaijiang-Liangping trough and Yanting （盐亭）-Tongnan （潼南） trough. Based on sedimentology and tectonics dynamics analysis, data of drillings, outcrops and seismic, Yanting-Tongnan trough has been discovered in central Sichuan basin in our study which distributes from Mianzhu （绵竹）, Jiangyou （江油） in western Sichuan basin through Nan-chong （南充） to Guang＇an （广安）, as long as about 210 km, extending in NW-SE nearly paralleling to Kaijiang-Liangping trough, opening to the sea north-westward, and gradually pinchout to the east platform. Similar to Kaijiang-Liangping trough, another platform margin reef belt distributes along a U-shape belt around Yanting-Tongnan trough, which is expected to become another natural gas accumulation zone after the platform margin around Kaijiang-Liangping trough. The discovery of Yanting-Tongnan trough expands favorable reef exploration area from original 2x 10^4 km2 on both sides of Kaijiang-Liangping trough to more than 6x10^4 km2 in Yanting-lbngnan trough platform margin belt and Kaijiang-Liangping platform margin belt, greatly enlarging the reef exploration field. But com-pared to Kaijiang-Liangping trough, YantingTongnan trough is relatively shallower and smaller, and the scale and quality of reef-bank reservoirs in its margin belt is a little poor relatively. Therefore, much research should be done timely such as comparative study of two troughs, detailed research of formation and evolution of the trough, regularity of reef migration, meticulous depiction of reef-bank reservoir size andDiscovery of Yanting-Tongnan Trough of Late Permian in Sichuan Basin and Its Significancedistribution in order to obtain major breakthroughs around the Yanting-Tongnan trough.

元坝气田成藏条件及勘探开发关键技术

梳理元坝超深层生物礁大气田的勘探开发历程可以发现,'开江—梁平陆棚'的厘定奠定了元坝台地边缘生物礁滩发现的基础。通过对油气成藏关键地质条件进行系统解剖,元坝地区礁滩发育具有沿'开江—梁平陆棚'成排成带分布、早滩晚礁、前礁后滩的特点,以侧积、前积迁移生长为主,飞仙关组不发育滩相优质储层,长兴组是主要勘探目的层;三期破裂、三期溶蚀作用和白云石化作用控制了优质储集层的发育;二叠系大隆组与吴家坪组两套烃源岩的有效叠加为大气田的形成提供了充足的气源;微小断层、微裂缝及层间缝共同构成的'三微'立体输导体系能够满足油气运聚的需要;元坝气田的成藏模式为:近凹富集、'三微'输导、岩性控藏、构造控富。针对元坝气田超深层、多压力系统等复杂地质条件,在勘探开发过程中形成了超深层生物礁滩储层精细预测与气水识别、复杂小礁体气藏精细描述和薄储层精细刻画、超深水平井优快钻井技术、复杂礁滩体超深水平井地质导向等关键技术,实现了元坝气田的高效勘探开发,推动了超深层油气勘探领域理论技术与方法的创新。