准噶尔盆地腹部八道湾组是侏罗系潜在的勘探接替领域.通过分析盆1井西凹陷八道湾组低位体系域砂体形成条件、沉积特征,结合成藏条件研究,提出了坳陷湖盆坡折之下发育低位体系域砂体,低位体系域砂体成藏条件优越:①盆1井西凹陷八道湾组发育1个完整的三级层序,凹陷周缘发育坡折,来自东部物源体系的辫状河三角洲向凹陷方向进积,在坡折之下的凹陷区卸载沉积物,为凹陷区低位体系域砂体的发育创造了条件.②盆1井西凹陷八道湾组发育低位体系域砂体,低位体系域砂体呈砂泥互层,侧向与三角洲平原河漫滩泥岩接触,顶底板和侧向遮挡条件较好,岩性圈闭条件优越,具有形成规模岩性圈闭群的条件.③盆1井西凹陷发育低孔特低渗低位体系域砂岩储层,局部发育的微裂缝改善了储层物性;凹陷发育二叠系风城组和下乌尔禾组2套烃源岩,烃源条件较好.④盆1井西凹陷周缘发育深浅2组断裂,在垂向上沟通八道湾组低位体系域砂体与二叠系烃源岩,有利于油气聚集成藏,勘探潜力大,为准噶尔盆地下一步天然气规模发现的有利勘探领域.

为了明确坳陷湖盆古地貌对沉积体系的控制作用,认识沉积体系展布规律,优选下一步勘探领域,以准噶尔盆地中部侏罗系三工河组二段为例,采用地层厚度法恢复了古地貌,细化了古地貌单元,并通过岩芯观察,识别了沉积微相,在此基础上,通过古地貌单元与沉积微相叠合分析,提出了坳陷湖盆沉积期古地貌对沉积体系、沉积微相和岩性圈闭的形成具有重要的控制作用.研究结果表明:准噶尔盆地中部三工河期为隆凹相间的古地貌格局,具有水下古低凸、水下古沟槽、古坡折和水下古平台等4类古地貌单元,发育湖泊-三角洲沉积体系,可进一步识别出水下分流河道、分流间湾、席状砂和砂质碎屑流微相.水下古沟槽充填水下分流河道微相砂体,水下古低凸主体部位发育分流间湾相泥岩,古坡折之下的水下古平台发育砂质碎屑流砂体.水下古低凸翼部发育的水下分流河道砂体向低凸方向超覆尖灭,水下古平台发育的砂质碎屑流砂体呈"泥包砂"结构,储层性质较优,岩性圈闭条件好,成藏条件优越,为下一步最有利勘探领域.

砂质碎屑流储层普遍非均质性较强,纵、横向变化快,储层预测难度大.因此,需要精细描述砂质碎屑流储层,以拓展油气勘探新领域.利用多属性融合技术预测砂质碎屑流储层面临属性优选,很难得到明确的解释结果.为此,利用GeoEast软件的核主成分属性优化技术与神经网络反演技术定性与定量预测砂质碎屑流储层,落实砂质碎屑流储层发育区.首先,分析砂质碎屑流地震响应特征,利用核主成分压缩技术定性预测砂质碎屑流;其次,利用敏感曲线(GR曲线)对砂质碎屑流储层的敏感性,利用神经网络反演定量预测砂质碎屑流有效储层的分布范围.结果表明,利用神经网络反演结果在平面上确定了 6个砂质碎屑流砂体,与钻井结果匹配较好.

为了明确准噶尔盆地白垩系清水河组是否发育低位体系域砂体、低位体系域砂体是否具有勘探潜力,对阜康凹陷清水河组低位体系域砂体形成条件、沉积特征和沉积模式进行了分析,并对成藏条件进行研究.结果 表明:准噶尔盆地白垩系清水河组底部为三级层序界面,且阜康凹陷沉降中心附近发育多级坡折,为低位体系域砂体发育创造了条件,并提出大型坳陷湖盆坡折之下发育多期低位体系域砂体,岩性圈闭条件优越.低位体系域砂体厚度大、面积广、储层优,侧向封堵条件优越,且研究区发育深层和浅层两组断裂,在垂向上构成"Y"形组合,可沟通烃源岩和低位体系域砂体,证实研究区低位体系域砂体成藏条件优越,为下一步岩性油藏最有利勘探领域.

为查明源储配置对致密油富集的影响,优选下一步致密油潜在有利区,在岩心和薄片观察的基础上,开展地球化学分析和扫描电镜、微米CT等测试,对川中地区大安寨段烃源岩和致密储层特征进行分析,并通过已知油藏解剖,对大安寨段致密油源储配置类型和平面展布进行了研究,发现源储互层式和上源下储式配置关系最有利于致密油富集.研究结果表明:川中地区大安寨段发育旁生侧旁生侧储储式、源储互层式和上源下储式等3种源储配置,烃源岩为最大湖泛期泥页岩,有机质含量0.54％～2.32％,干酪根类型以腐泥型为主,处于成熟—高成熟阶段;储集空间类型包括溶蚀孔洞和基质孔隙,分别发育于厚层介壳灰岩和中—薄层泥质介壳灰岩中,孔隙度0.38％～6.82％,平均1.67％,渗透率多低于0.1×10-3μm2,为特低孔致密储层.现有勘探实践证明油田源储配置关系以源储互层式和上源下储式为主,秋林、仪陇、渠县、李渡和广安地区以该类源储配置关系为主,为下一步致密油潜在有利区.

为了进一步了解玛湖凹陷下二叠统风城组沉积环境,通过现代碱湖和主要碱矿进行调研,系统梳理了现代碱湖沉积特征,并与风城组沉积特征进行了对比研究,提出了现代碱湖沉积对玛湖凹陷风城组沉积环境具有可对比性.研究结果表明:玛湖凹陷风城组沉积期为一大型碱湖盆地,与世界上典型碱湖特征基本相近,自生矿物、沉积组合与演化过程大致相同,为形成于半干旱气候环境的闭流盆地,含碱层段一般为浅水环境成因,是碳酸盐型湖水蒸发浓缩的产物,与碱层互层的暗色细粒岩石不全为深水沉积产物.

为了弄清准噶尔盆地凹陷区是否发育有效砂体、岩性圈闭是否落实,基于岩心观察、重矿物分析、储层表征和地震反射特征分析等方法,分析了该盆地盆1井西凹陷下侏罗统三工河组二段(以下简称三二段)古地貌、沉积微相、储层性质和含油气性,评价了砂质碎屑流砂体的岩性圈闭条件,明确了准噶尔盆地三工河组下一步天然气勘探的方向.研究结果表明:①盆1井西凹陷周缘三二段发育坡折带,坡折带之上三角洲前缘砂体发育,在燕山期构造活动的触发下,滑塌至坡折带之下的半深湖形成砂质碎屑流砂体;②砂质碎屑流砂体厚度大,垂向上具有“泥包砂”结构,侧向与前缘相砂体之间存在泥质分隔带,封堵条件较好,岩性圈闭条件优越;③砂质碎屑流砂体储层物性好,属于中等—较好的储集层,砂质碎屑流砂体整体含油气性较好.结论 认为:①准噶尔盆地三工河组发育砂质碎屑流砂体,岩性圈闭条件优越,具有重要的油气勘探意义;②基于该研究成果,通过新钻井已取得了油气勘探重大突破,证实坡折带之下砂质碎屑流砂体岩性油气藏成藏条件优越,是该区下一步最有利的天然气勘探新领域.

为明确和拓展准噶尔盆地岩性油气藏和复合油气藏勘探新领域,以盆地莫北区块侏罗系三工河组二段为例,综合利用钻井、测井、分析化验以及地震等数据和资料,对三工河组浅水三角洲的储层特征和勘探前景进行了研究.结果表明:储层砂岩以粗粒、中粗粒长石岩屑砂岩为主,具有中—低孔隙度和渗透率,以剩余原生粒间孔为主,孔喉微观结构和渗流能力中等—较好.沉积体系类型为浅水辫状河三角洲—湖泊体系,依据两级坡折带识别出内前缘、外前缘、砂质碎屑流等主要亚相;前缘水下分流河道砂体为骨架砂体,分为粗粒厚层块状和中细粒中薄层似块状2种类型,垂向多套,侧向切割、叠置,平面上宽条带状分布,朵叶体呈朵状或鸟足状,构成了前缘复合体.河道砂体储集条件和储层质量好,且多期砂体叠置连片分布,分布范围广、面积大;同时,具有良好遮挡和封堵、烃源以及输导条件,易形成规模岩性或复合油气藏,勘探前景良好.研究成果对深化和落实盆地勘探新领域具有指导作用.

为详细解剖水下分流河道沉积特征,探讨其岩性圈闭意义,采用多参数分析方法,对水下分流河道微相沉积特征进行了分析,提出了发育于不同古地貌单元的水下分流河道微相砂体由于物性存在差异而对岩性圈闭的形成具有重要意义.研究结果表明:研究区三工河组二段发育古低凸和古沟槽2种古地貌单元,古沟槽发育反旋回叠置型水下分流河道,低凸翼部发育正旋回叠置型水下分流河道.正旋回叠置型水下分流河道砂体物性自下而上逐渐变差,在侧向对反旋回叠置型水下分流河道储集体构成侧向遮挡,有利于形成岩性圈闭.在此基础上建立了岩性圈闭模式,将该模式应用到油田预探井井位部署中,取得了很好的效果.

为明确湖相含油气沉积盆地凹陷区半深水-深水环境储层砂体沉积特征、模式以及岩性地层型油气藏新目标区勘探前景,以准噶尔盆地盆1井西凹陷为例,系统总结国内外砂质碎屑流研究成果和认识,以岩心、录井、测井和地震资料为基础,剖析侏罗系三工河组二段储层砂体沉积背景、识别标志、沉积特征、沉积模式,认为半深湖-深湖区规模发育辫状河三角洲供源型砂质碎屑流沉积,储层特征和质量与水下分流河道相当.研究结果表明:沉积相带受两级坡折控制分为辫状河三角洲内前缘、外前缘及(砂质)碎屑流带.砂质碎屑流粒度较粗,具有(大套)块状砂岩、突变接触、漂浮泥砾和泥质撕裂屑等主要识别标志,正、反旋回均有发育,平面上呈舌状或似朵状.储层平均孔隙度和渗透率分别为12.5％和5.51 mD,为中-低孔、中-低渗有效储层.储盖组合和侧向遮挡条件有利,烃源条件好,油气充注足,易形成规模岩性油气藏,勘探前景好.

为了弄清准噶尔盆地腹部白垩系清水河组沉积体系和微相砂体展布,落实下一步岩性油藏勘探领域,采用残余地层厚度法恢复了古地貌,识别了古地貌单元,并通过岩心观察、测井相和地震相分析,研究了沉积体系和微相发育特征,提出了水下古沟槽侧翼向低凸超覆尖灭的水下分流河道砂体有利于形成上倾尖灭型岩性圈闭,研究结果表明:石南低凸、夏盐低凸、三个泉低凸、石东低凸和滴南低凸侧翼水下分流河道砂体厚度5～20 m,平均孔隙度12％～28％,平均渗透率10～2 490 mD,侧向受低凸主体部位分流间湾和滨浅湖泥岩封堵,顶部发育“高伽马”泥岩,平均厚度20～60 m.低凸分布区发育深层和浅层2组断裂,深层断裂沟通二叠系烃源岩且与浅层断裂呈“Y”型配置,构成良好油气运移通道,证实5个低凸翼部成藏条件优越,为下一步岩性油藏最有利勘探领域.

The 3rd upper sub-member of the Silurian Kepingtage formation has developed marine clastic sediments and is an important petroleum exploration and development set in Tazhong area, Tarim basin, NW China, of which the sedimentary system and favorable reservoir distribution have been researched in detail based on the drilling, logging, seismic, experimental data and the theory of sequence stratigraphy. The results show that it was overlap and edge away layer by layer from northwest to southeast. On the background of marine transgression, the depositional systems of tidal flat, estuary and tidal reformation delta were developed and controlled by palaeogeomorphology, while different types of sand bodies and sedimentary formations were developed owing to the difference of types and energies of main action water bodies. In the sedimentary system of tidal flat, the main types of sand bodies are subtidal tidal channels which show significantly banded distribution vertical to the coast with a complete three-tier structure. The sand bodies of tidal bars are common in the estuary sedimentary system and extend far parallel to the axis of the estuary with thin layers of mudstone. The sand bodies of underwater distributary channels are developed with upward-finning positive rhythm and large erosion surfaces in the tidal delta sedimentary system and distributed like a bird-foot shape. By above research, the depositional mode of tidal flat-estuary-delta in Tazhong area has been established and the distribution of favorable reservoirs has been predicted.

The Sinian Dengying Formation strata in the Sichuan Basin are interpreted to be the oldest marine carbonate strata and gas reservoirs in China.In the last geologic periods, the Dengying Formation underwent multiple phases of karstification, of which the supergene karstification have played an important part in the formation of the excellent reservoir rocks in the Formation.Therefore, the emphasis in the present paper is placed on the supergene karstification in the Sinian Dengying Formation on the basis of macroscopic and microscopic features, and multi-parameter experimental analysis of samples from the field outcrops and drilled cores in the Sichuan Basin.The supergene karstification occurs dominantly in three horizons, including the topmost parts of the 4th member and the 2nd member, and lower and middle parts of the 2nd member of the Dengying Formation.The tectonic movements during the Tongwan I and II episodes are believed to be the main controlling factors for the supergene karstification in the topmost parts of the 4th member and 2nd member of the Dengying Formation.The supergene karstification in the lower and middle parts of the 2nd member of the Dengying Formation is mostly constrained by the large-scale sea level changes caused by climatic variations.

The tectonic environment of Mahu sag in Junggar basin was relatively stable in Badaowan stage of Early Jurassic,during which grooves and slopes were developed and the sediment supply was sufficient,providing conditions for development of braided rive delta.The sediments of the braided river delta that are characterized by coarse grain,low maturity,developed tractive-current depositional structure,incision and superimposition of multi-stage underwater distributary channel vertically and normal cycle of sedimentary sequence and so on,can be divided into 2 subfacies such as braided-river delta plain and braided-river delta front.On the plane,different slope gradients in different areas result in the differences of sizes of braided river deltas whose sizes are relatively large in steep slopes and relative small in gentle slopes.Vertically,different subfacies associations and sandbody configuration were developed at different stages of lake level rising.Braided-river delta plain was mainly found at the early stage of lake level rising;braided-river delta front was the dominant subfacies at the middle stage of lake level rising;mud-coated sand type of braided-river delta front was developed at the late stage of lake level rising.

Oil and gas shows are active in the red-brown sandy mudstone interval under the unconformity surface between Jurassic and Cretaceous strata on the southern slope of Mosuowan swell.High-yield commercial oil flow has been gained from several wells drilled by Sinopec in the sandy mudstone interval and then Yongjin oilfield has been discovered.However,the classification of horizon of the interval has always been controversial.On the basis of the latest 2D seismic data and combining with well logging-seismic calibration,the paper performs 2D & 3D merging detailed seismic geological interpretation in the study area.Combined with the comparative analysis of core and microscopic features under microscope,it is considered that the red-brown sandy mudstone interval which is widely distributed at the top of Jurassic in Mosuowan swell should be classified into the Middle Jurassic Toutunhe formation.The re-classification of the horizon identifies that the major target zone in the study area is the Toutunhe formation which has favorable conditions for large-scale hydrocarbon accumulation,and indicates further exploration direction on the southern slope of Mosuowan swell.

The sedimentary characteristics of Lianggaoshan Formation in central Sichuan Basin was studied based on field outcrop and core observation,combined with grain size analysis,well log and seismic facies analysis.The result showed that the upper Lianggaoshan Formation was deposited in lacustrine environment in central Sichuan Basin,with beach-bar sand bodies extensively developed.The beach-bar can be divided into two types of microfacies,i.e.sand beach and sand bar.In the plan view,beach-bar distributed along the lake shoreline,whereas the sand bar distributed in the sand beach.On this basis,the sedimentary model of Lianggaoshan Formation in Sichuan Basin was built,and the sand bar sand body was identified as the "sweet spot" for tight oil exploration of upper Lianggaoshan Formation in central Sichuan Basin.

Core and microscope observations reveal that the three types of rocks in the Jurassic Da'anzhai Member of the Central Sichuan Basin,which include shell limestone,muddy shell limestone,and shaly shell limestone,are the sedimentary products of the shell beach in the shallow-semi-deep lake environment.We determined the following sedimentary microfacies on the shell beach based on logging and seismic facies studies:main beach,beach wing,and slope before beach.The distribution of the microfacies is controlled by the ancient landform.The main beach is distributed on the underwater paleo-uplift,the beach wing surrounds the uplift,and the slope is distributed in the transitional area between the underwater paleo-uplift and the depocenter.The evolution and migration of the shell beach is controlled by the lake level changes.When the lake level rises,the shell beach migrates from the low uplift of the depocenter to the periphery uplift of the basin.When the lake level declines,the shell beach migrates from the periphery uplift of the basin to the low uplift of the depocenter.

According to the relation to strata erosion, the paleotectonic framework of three uplifts and one sag developed before Middle Permian in Sichuan Basin. Based on field profile, core, thin-section, logging data, and seismic facies analysis, it is claimed that carbonate rimmed platform develope in Qixia Stage and Maokou Stage, in which some subfacies developed such as platform margin, open platform and platform basin, furtherly more microfacies can be identified including platform margin beach, inner-platform beach and siliceous platform basin. Controlled by paleotectonic framework, platform margin developed along the transition zone between the old uplift and slope-basin or between open platform and platform basin. Open platform developed in the old uplift and low uplift. Platform basin developed in the low sag. Comparing with the oil and gas exploration in Upper Permian Changxing Fm. and Lower Triassic Feixianguan Fm., it is suggested that the platform mar-gin formed during Qixia Stage and Maokou Stage would be the next favorable exploration realms.

Depending on the data of high-resolution image log and the geological calibration of dolostone core samples from Well Kuang-2 in the northwest of Sichuan Basin,a typical profile of Lower Permian Qixia dolostone reservoir structure is characterized,by which five types of dolostone and limestone and four types of effective reservoir spaces can be identified.It is shown that multiple pore system develops in Qixia dolostone,in which solution pores and intercrystal pores are contributive commonly.The solution pores appear as layers or quasi-layers in massive medium-and coarse-graine d dolostone (in one strata unit with the thickness of 39.5m) and the intercrystal pores exist in porphyritic medium- and coarse-grained dolostone (in 4 strata units with the average thickness of 1.1m).Other two types of reservoir space,including solution-enlarging fractures and late structural fractures are less contributive.The massive dolostone develops in the HST of the 3rd sequence but the porphyritic dolostone only develops in the upper part of the upward-shallowing cycle of the 4th sequence.

四川盆地川中地区大安寨段致密灰岩属于典型的"致密油"储层,在研究其储层特征的同时,重新划分了亮晶介壳灰岩、泥质介壳灰岩、泥晶介壳灰岩及结晶灰岩等4类主要的储集岩性,详细研究了溶蚀孔洞、次生微孔、裂缝及纳米级孔这4类储集空间的特征,建立了致密灰岩储层连续型似"网状"储集空间组合模型.通过分析沉积微相、溶蚀作用和构造作用对储层的控制和影响,指出在低能介壳滩主要发育基质微孔储集层,在高能介壳滩主要发育溶蚀孔洞储集层,由此确定了多种储集空间类型组合叠置、大面积连续分布的储层发育模式.基质微孔与溶蚀孔洞型储集层连续分布区是致密灰岩储层的"甜点"区.