Complex Exploration Techniques for the Low-permeability Lithologic Gas Pool in the Upper Paleozoic of Ordos Basin

The Ordos basin is a stable craton whose late Paleozoic undergoes two sedimentary stages: from the middle- late Carboniferous offshore plain to the Permian continental river and lake delta. Sandstones in delta plain channels, delta-front river mouth bars and tidal channels are well developed. The sandstones are distributed on or between the genetic source rocks, forming good gas source conditions with widespread subtle lithologic gas pools of low porosity, low permeability, low pressure and low abundance. In recent years, a series of experiments has been done, aimed at overcoming difficulties in the exploration of lithologic gas pools. A set of exploration techniques, focusing on geological appraisal, seismic exploration, accurate logging evaluation and interpretation, well testing fracturing, has been developed to guide the exploration into the upper Paleozoic in the basin, leading to the discoveries of four large gas fields: Sulige, Yulin, Wushenqi and Mizhi.

Research Advances and Exploration Significance of Large-area Accumulation of Low and Medium Abundance Lithologic Reservoirs

In recent years, a series of large low and medium abundance oil and gas fields are discovered through exploration activities onshore China, which are commonly characterized by low porosity-permeability reservoirs, low oil/gas column height, multiple thin hydrocarbon layers, and distribution in overlapping and connection, and so on. The advantageous conditions for large-area accumulation of low-medium abundance hydrocarbon reservoirs include： （1） large （fan） delta sandbodies are developed in the hinterland of large flow-uncontrolled lake basins and they are alternated with source rocks extensively in a structure like ＂sandwiches＂; （2） effective hydrocarbon source kitchens are extensively distributed, offering maximum contact chances with various sandbodies and hydrocarbon source rocks; （3） oil and gas columns are low in height, hydrocarbon layers are mainly of normal-low pressure, and requirements for seal rock are low; （4） reservoirs have strong inheterogeneity and gas reservoirs are badly connected; （5） the hydrocarbon desorption and expulsion under uplifting and unloading environments cause widely distributed hydrocarbon source rocks of coal measures to form large-area reservoirs; （6） deep basin areas and synclinal areas possess reservoir-forming dynamics. The areas with great exploration potential include the Paleozoic and Mesozoic in the Ordos Basin, the Xujiahe Formation in Dachuanzhong in the Sichuan basin, deep basin areas in the Songliao basin etc. The core techniques of improving exploration efficiency consist of the sweetspot prediction technique that focuses on fine characterization of reservoirs, the hydrocarbon layer protecting and high-speed drilling technique, and the rework technique for enhancing productivity.

Structural features and exploration targets of platform margins in Sinian Dengying Formation in Deyang-Anyue Rift, Sichuan Basin, SW China

Based on the seismic, logging, drilling and other data, the distribution, structural types and mound-shoal hydrocarbon accumulation characteristics of platform margins of the Sinian Dengying Formation in the Deyang-Anyue Rift and its periphery were analyzed. Four types of platform margins are developed in the Dengying Formation, i.e., single-stage fault-controlled platform margin, multi-stage fault-controlled platform margin, gentle slope platform margin, and overlapping platform margin. In the Gaoshiti West-Weiyuan East area, single-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in nearly NEE direction and are shielded by faults and mudstones, forming fault-controlled–lithologic traps. In the Lezhi-Penglai area, independent and multi-stage fault controlled platform margins are developed in the Deng 2 Member, which trend in NE direction and are controlled by synsedimentary faults;the mound-shoal complexes are aggraded and built on the hanging walls of the faults, and they are shielded by tight intertidal belts and the Lower Cambrian source rocks in multiple directions, forming fault-controlled–lithologic and other composite traps. In the Weiyuan-Ziyang area, gentle slope platform margins are developed in the Deng 2 Member, which trend in NW direction;the mound-shoal complexes are mostly thin interbeds as continuous bands and shielded by tight intertidal belts in the updip direction, forming lithologic traps. In the Gaoshiti-Moxi-Yanting area, overlapping platform margins are developed in the Deng 2 and Deng 4 members;the mound-shoal complexes are aggraded and overlaid to create platform margin buildup with a huge thickness and sealed by tight intertidal belts and the Lower Cambrian mudstones in the updip direction, forming large-scale lithologic traps on the north slope of the Central Sichuan Paleouplift. To summarize, the mound-shoal complexes on the platform margins in the Dengying Formation in the Penglai-Zhongjiang area, Moxi North-Yanting area and Weiyuan-Ziyang area are large in scale, with estimated resources of 1.58×1012 m3, and they will be the key targets for the future exploration of the Dengying Formation in the Sichuan Basin.

Formation Conditions and Exploration-favoring Areas of Subtle Reservoirs in West Taibei Sag

At the initial stage of subtle reservoir exploration in the shallow to medium formations of the Taibei Sag, Tuha Basin, so far, three kinds of subtle reservoirs (stratigraphic, lithologic and structural-lithologic reservoirs) have been found. Since both the amount and reserve of the discovered subtle reservoirs are small, a great exploration potential remains in the Taibei Sag. The shallow to medium formations in the west of the Taibei Sag were divided into three second-order sequences and ten third-order sequences, of which the rising cyclothems of SQ(J2q) and SQ8 (J2s2) datum level are major exploration targets for the subtle reservoirs (lithologic). The depositional systems of Qiquanhu and Subashi braided river delta were developed there, where the sedimentary sand body is dominated by the regional slopes and slope break belts. There are four main modes the formation of lithologic traps: deltaic front onlap on the slope belt, deltaic front toplap on the slope break belt, lately tilted frontal sand body and sublacustrine fan—slope fan on the slope break belt, of which the first three modes are the major styles of the formation of subtle reservoirs. Major targets for subtle reservoir exploration in the near future include Putaogou Member on the north slope of Huoyanshan, the east slope of Pubei, the nose-like palaeohigh regions of Huobei, Subashi and Lianmuqin, around the Shengbei secondary sag.

Neural Network Applications in Petroleum Exploration Based on Statistical Space Mapping

In this paper, we propose the statistical space mapping thought and classify the seismic body space throughlithology space clustering combining to the actual application background of petroleum exploration. A new method ofstratum petroleum recognition based on neural network was set up through the foundation of the data mapping relationbetween log and seismic body. It can break a new path for recognition petroleum using both log and seismic data. Andthis method has been validated in the practical data analysis in Liaohe oil field.

A Real-time Lithological Identification Method based on SMOTE-Tomek and ICSA Optimization

In petroleum engineering,real-time lithology identification is very important for reservoir evaluation,drilling decisions and petroleum geological exploration.A lithology identification method while drilling based on machine learning and mud logging data is studied in this paper.This method can effectively utilize downhole parameters collected in real-time during drilling,to identify lithology in real-time and provide a reference for optimization of drilling parameters.Given the imbalance of lithology samples,the synthetic minority over-sampling technique(SMOTE)and Tomek link were used to balance the sample number of five lithologies.Meanwhile,this paper introduces Tent map,random opposition-based learning and dynamic perceived probability to the original crow search algorithm(CSA),and establishes an improved crow search algorithm(ICSA).In this paper,ICSA is used to optimize the hyperparameter combination of random forest(RF),extremely random trees(ET),extreme gradient boosting(XGB),and light gradient boosting machine(LGBM)models.In addition,this study combines the recognition advantages of the four models.The accuracy of lithology identification by the weighted average probability model reaches 0.877.The study of this paper realizes high-precision real-time lithology identification method,which can provide lithology reference for the drilling process.

川东地区龙潭组页岩岩性序列及勘探意义

川东地区龙潭组具有较大的页岩气勘探前景,该地层沉积于海陆过渡环境,沉积相变化快,岩性复杂,存在难以通过常规的矿物成分方法划分岩相以及当前岩相划分尚不精确的问题,制约了该地区龙潭组页岩有利岩相带识别及勘探。本文基于岩心观察、野外剖面实测和薄片鉴定,结合钻井的泥地比、单层岩性厚度,建立了川东地区龙潭组7种特征岩性组合模式(泥页岩型、富泥含砂型、富泥含灰型、灰泥互层型、富灰含泥型、致密灰岩型和火成岩型);综合TOC、孔隙度、含气性、脆性指数等页岩储层特征参数,明确了不同岩性组合在龙潭组各段的平面分布规律。研究表明,纵向上优势岩性组合主要为龙潭一段富泥含灰型和泥页岩型,龙潭二段主要为泥页岩型、灰泥互层型和富泥含灰型。平面上龙潭一段优势岩性组合富泥含灰型主要分布在开州—云阳一带,泥页岩型主要分布在重庆—綦江一带;龙潭二段优势岩性组合泥页岩型分布在巴南—綦江一带,灰泥互层型分布在达州一带,富泥含灰型分布在万州—梁平—石柱一带。该项研究成果为川东地区龙潭组页岩气勘探提供了重要依据。

柴西南区岩性油气藏地质特征及控制因素

近年来,柴达木盆地在咸化湖相滩坝砂中发现了多个“小而肥”的岩性油气藏。为了拓展岩性油气勘探规模、发现新的目标及区带,支撑油田规模增储上产,利用岩心、测井和地震资料,开展岩性油气藏成藏条件综合分析。通过解剖已发现岩性油气藏特征,明确控制因素,指出了岩性油气藏勘探接替领域。结果表明,柴西南区具备形成岩性油气藏的四大有利条件:一是发育继承性的七个泉—红柳泉、砂西—跃进、扎哈泉—乌南三大稳定的古斜坡,利于油气聚集成藏;二是临近红狮和扎哈泉两个生烃中心,油源条件优越;三是咸化湖盆发育大型辫状河三角洲、广覆式分布的滨浅湖滩坝砂及藻席—灰云坪沉积,形成碎屑岩和碳酸盐岩两种互补型的储集体;四是发育多种疏导体系,纵向上可以形成多套含油层系。受古构造、沉积、成岩等多因素控制,柴西南区发育砂岩上倾尖灭型、砂岩透镜体型、物性封堵型和白云石化成岩圈闭四种类型岩性油气藏。岩性油气藏受古构造、优质源岩和有效储层三因素控制。古构造决定岩性圈闭的类型和油气运移方向;优质烃源岩控制岩性油气藏的分布及规模;有效储层控制岩性油气藏的富集。综合评价指出,辫状河三角洲前缘砂体是古近系下干柴沟组下段岩性勘探的有利区,主要分布在砂西、尕斯、乌南向盆内的倾末端;白云石化成岩圈闭是古近系下干柴沟组上段岩性勘探的有利区,主要分布在环红狮凹陷周缘;广覆式分布滩坝是新近系上干柴沟组、下油砂山组岩性油气藏勘探的有利区,主要分布在英雄岭、尕斯、扎哈泉、乌南等地区。这一认识支撑了切探2井、尕斯新层系等岩性勘探获得一系列重大突破,可为柴西南区岩性油气藏的下一步勘探提供指导。

渤海湾盆地沙南凹陷古近系中深层砂岩储层特征与岩性油气藏勘探

渤海湾盆地沙南凹陷陡坡带古近系沙河街组二段发育辫状河三角洲相砂岩储集层,该储层受构造位置、埋藏速率、古地温变化、断裂作用的影响,在不同构造区特别是中深层,其物性具有明显的差异性。笔者等利用钻井、测井、地震及分析化验等资料,对中深层砂岩储层沉积相、成岩作用及孔隙演化特征进行研究,提出优质储层的主控因素及演化规律。结果表明,研究区中深层砂岩以岩屑长石砂岩为主,孔隙以粒间溶孔、粒内溶孔为主,储层存在中孔中渗型、中孔低渗型、低孔低渗型和低孔特低渗型4类,且以中孔低渗型为主。储层孔隙总体比较发育,储层整体表现为中等孔隙度、中等渗透率,储层物性较好。对区内优质储层发育的控制因素进行研究表明,富含石英、长石的物源区母岩是区内优质储层发育的物质基础,三角洲分流河道沉积相是优质储层发育的主要沉积相类型,成岩晚期方解石胶结物经过强溶蚀作用是优质储层发育的关键因素。对中深层优质储层时空演化规律分析表明,沙南凹陷南次洼曹妃甸14-e构造区发育辫状河三角洲相砂体,且这些砂体都位于有效烃源岩内,油气运聚条件优越,所以岩性油气藏勘潜力较大。已钻井也证明了区内厚油层的存在,说明该区是沙南凹陷岩性油气藏勘探最有利场所。

波阻抗反演在煤层底板岩性预测中的应用

叠后波阻抗反演利用波阻抗差异区分地质体岩性,是常用的煤层顶底板岩性预测方法,在煤层安全开采以及工作面施工等方面发挥了重要作用。以实际工区为例,对反演过程中的关键技术进行了详细阐述,并基于实际地质、测井、地震资料,针对反演目的区域测井资料不足的问题,使用不同采样率的地震数据开展波阻抗反演,得到不同尺度的反演结果。结果表明在测井数量不足以及测井曲线深度未能完全覆盖目的层时,较大尺度的反演结果在分辨率上虽然存在不足,但能更好地刻画岩层结构和岩性变化,更贴近工区实际情况。

高斯混合模型在水系沉积物地球化学异常圈定中的应用:以湖南省溆浦地区为例

化探数据的正确处理和解译对于区域矿产勘查工作具有重要意义。然而,由于不同类型的岩石具有不同的元素丰度,在处理复杂岩性区化探数据时如果采用统一的异常下限,会导致高背景区被误判为异常区,而部分低弱地球化学异常被忽略。所以复杂岩性区的化探数据需按岩性分类后再划分地球化学背景与异常,从而更准确地圈定化探异常。提出了基于因子得分高斯混合模型的化探异常圈定方法,首先将化探数据做对数比转换后进行因子分析,然后利用因子得分完成高斯混合模型岩性分类,再进行分类标准化处理以消除岩性背景的影响,最后使用处理后的数据圈定化探异常。利用该方法对湖南溆浦地区1∶20万水系沉积物化探数据进行研究,结果表明,成矿元素在研究区不同岩性中的含量存在一定差异,若采用统一的异常下限是不合理的;而本研究提出的方法能准确地进行岩性分类、消除不同岩性的背景和强化低弱异常,且异常位置与已知矿点相吻合。因此,高斯混合模型方法可以准确地圈定复杂岩性区的化探异常,并为研究区下一步的矿产勘查工作提供一些参考依据。

渤海海域浅层岩性勘探新进展与勘探关键技术

随着勘探程度的提高,渤海海域浅层规模型构造圈闭已经钻探殆尽,向岩性勘探转移势在必行。但浅层岩性勘探在规模型砂体展布、油气富集模式、薄层砂体边界精细刻画及烃检等方面仍面临诸多问题与挑战。基于全覆盖三维地震资料和分析化验资料,开展了浅层区域沉积格局和油气成藏规律研究,明确了迁移型曲流河、稳定型曲流河、河-湖交互沉积发育模式及规模型砂体分布规律,建立了高凸起区、低凸起区、凹中隆起区和洼陷区4类浅层大面积岩性油气富集模式,同时创新形成井震匹配高分辨率波阻抗反演的砂体描述技术和基于频变AVO特征差异的综合烃类检测技术,推动了渤海海域浅层大面积岩性勘探获得重大突破,发现了垦利6-1、垦利10-2、渤中19-2和秦皇岛27-3等大中型油田。系统总结渤海海域浅层岩性勘探成果,以期对陆相断陷盆地浅层规模型岩性油气藏勘探起到借鉴作用。

渤海海域浅层岩性油藏勘探作业技术进展

近年来,新近系浅层岩性油藏逐步成为渤海海域勘探储量发现的重要领域,浅层岩性油藏以河流相沉积及浅水三角洲沉积为主,储层平面展布广,垂向薄砂厚泥互层,岩性疏松且油质黏稠,导致勘探作业成本高,钻井取心卡层、原油样品及商业性产能获取难度大。“十三五”以及“十四五”期间,渤海油田产学研用结合,在浅层勘探钻井提效、浅层勘探资料录取(疏松砂岩钻井取心、疏松砂岩稠油电缆取样)、浅层勘探产能释放(地化原油密度预测、疏松砂岩稠油冷采测试)、浅层勘探解释评价(低对比度油层识别)等4个方面,逐步建立了渤海油田浅层勘探作业技术体系。2019—2023年,低成本、高成效评价4个大中型浅层岩性稠油油田,为渤海浅层岩性勘探的持续深入奠定了坚实的技术基础,对推动中国海油浅层岩性勘探开发具有重要借鉴意义。

地震沉积学在复杂斜坡带岩性勘探中的应用研究

西湖凹陷西部斜坡带平湖组发育岩性气藏,主力气藏区埋深大、岩性组合复杂,砂泥岩识别难度大。同时,地震资料分辨率不足,导致岩性体厚度吻合度差、边界识别难度大。基于地震沉积学思想,在识别岩性基础上,应用分频技术刻画不同厚度岩性体;在此基础上应用分频地层切片匹配古地貌,刻画岩性体展布范围。通过地震沉积学的研究应用,在研究区有效识别了岩性体发育模式并取得勘探发现。

渤海海域明化镇组下段砂体构型与连通性分析

渤海海域浅层明化镇组下段时期,沉积体系复杂、类型多样,已发现的岩性油藏主要发育在曲流河和浅水三角洲中,砂体横向变化快,接触关系复杂,形成了储层空间展布及内部结构复杂的砂体,砂体构型及连通性决定了砂体发育规模及其展布范围,控制了岩性圈闭的大小及其油气分布。根据岩心、测井和地震等资料,对渤海海域浅层明化镇组下段砂体构型开展精细解剖,建立复杂沉积体系砂体构型模式,开展储层构型控制的砂体分布及演变特征研究,分析单砂体内部连通性。结果表明:曲流河砂体之间垂向叠置关系包括独立型、叠加型与切叠型,平面叠置关系主要以侧接型为主,以条带状展布为典型特征;浅水三角洲砂体构型要素主要由分流河道、河口坝和席状砂组成,垂向上以对接型、切叠型为主,平面上呈现枝状、朵状和片状展布。在砂体构型样式分析的基础上,运用三维地震、地球化学等资料和手段,结合构造和沉积特征,通过砂体叠置模式对比、原油运移充注分析和三维地震储层预测技术等方法,有效判识了明下段砂体的连通性,为浅层岩性圈闭落实和大面积岩性勘探提供借鉴。

海洋宽频高精度地震处理技术及其深层岩性勘探实践

近海平缆三维地震资料的宽频高精度处理在岩性油气藏勘探中越来越受到重视,但尚缺少专门分析论述。以东海西湖凹陷西斜坡深层精细岩性勘探为目标,通过发展波动方程延拓迭代减法去除鬼波、叠前综合多域去噪、浅水区组合去多次波,以及基于目标体的精细速度建模和偏移成像等技术手段的综合应用及效果分析,建立了海上平缆三维地震资料的宽频高精度处理技术流程,并将其应用于西湖凹陷西斜坡实际资料处理中,实现高分辨率宽频保幅高精度地震处理。利用宽频资料开展深层岩性油气藏的精细描述,有效实现了油气田增储扩边和深层优质岩性气田新发现,以助力海上深层岩性油气藏勘探开发。

激发极化测深法对洛阳市浅层地热勘查的研究

洛阳市地热资源勘查及开发利用对支撑城市经济绿色发展具有极为重要的意义。研究区位于洛阳盆地内,地形地貌类型较为复杂,采用常规的方法在地热勘查中收效甚微,而地球物理探测方法具有成本低、高效且适用性强等特点,在目前地热勘查中发挥了极其重要的作用。在系统梳理研究区地形地貌、地层岩性、水文地质特征以及岩石地球物理性质等资料基础上,选用激发极化测深手段通过电测深曲线特征对比分析、物探数据精准采集、测深成果反演解释以及异常推断等细致的研究过程,基本查清了225 m以浅研究区地层岩性、构造分布等,并推断含水层空间分布情况,可为区域间接寻找浅层地热资源提供支撑,为下一步寻找地热资源布设钻孔提供了充足的依据。

南海西部原油领域勘探进展与突破方向

南海西部原油领域历经多年勘探,探明程度高,勘探难度日益增大。近年来,转变思路,大力拓展新领域。攻关岩性圈闭发育机制,建立了流三段“低位转换带控砂,湖侵互层叠置连片”的广覆式砂体沉积模式,阐明了大面积连片岩性圈闭形成机理,创建了“近源广覆式有序富集”成藏模式,发现南海西部首个大中型岩性油田;攻关深层大型储集体和优质储层发育机制,建立构造-层序-地貌耦合控砂分析技术,提出了限制型辫状河三角洲发育模式,明确了相带与溶蚀差异控储机制,涠西南凹陷B洼深层、乌石凹陷反转构造带倾末端、文昌B凹陷双古领域获得了勘探突破。同时明确了大型构造脊大型储集体耦合的深层领域、富烃凹陷周缘地层-岩性圈闭领域、源储对接潜山领域和烃源条件落实边部凹陷是南海西部原油领域下步重点勘探方向。

歧口凹陷斜坡区岩性油气藏勘探实践与认识

历经40多年勘探的歧口凹陷,勘探难度越来越大,发展需求越来越紧迫。面临新的形势,大港油田立足丰富的资源基础,解放思想,转变勘探理念,推进"三个整体、四个精细"的勘探做法,即整体采集、整体研究、整体评价和精细目标处理、精细目标研究、精细方案设计、精细组织实施,强化斜坡区岩性油气藏的深入研究与勘探,先后在歧北斜坡、埕海断坡、滨海断鼻及斜坡发现了3个亿吨级规模储量区。通过斜坡区岩性油气藏的勘探实践,取得了两点主要认识、四点重要启示,对深化大港探区富油气凹陷斜坡区岩性油气藏勘探具有重要的指导作用。

中国岩性油气藏区带类型、地质特征与勘探领域

通过松辽盆地断陷和坳陷、鄂尔多斯盆地中生界坳陷、渤海湾盆地断陷和坳陷、准噶尔盆地中生界坳陷、川西前陆盆地、塔里木克拉通盆地等4大类原型盆地36个典型油气藏解剖和大油气区成藏条件分析,从油气聚集区域和勘探选区的角度,完善岩性油气藏区带分类方案体系。揭示了3类斜坡、3种凹陷中心、3种成藏组合、多种成因类型的岩性油气藏成藏特征和主控因素。基于不同类型大油气区成藏机制与富集规律认识,建立烃源条件、断层及输导体系、储集条件、储盖组合、流体性质和时空匹配等岩性油气藏区带6大类评价指标、参数体系及分级标准。结合油气形成演化的埋藏史、生油史、成岩史、构造史、圈闭史和成藏史等"六史"综合评价研究,进行岩性油气藏区带评价优选。评价预测松辽和渤海湾盆地富油气凹陷中浅层斜坡带、鄂尔多斯盆地中生界、准噶尔盆地二叠系—侏罗系等未来主要石油勘探领域,资源规模约(42~67)×108 t,以及松辽盆地深层火山岩、准噶尔盆地石炭系、塔里木盆地和四川盆地寒武系、四川盆地二叠系—三叠系台缘台内礁滩等未来主要天然气勘探领域,资源规模约(1.5~2.0)×1012 m^3。