New insights into the carbonate karstic fault system and reservoir formation in the Southern Tahe area of the Tarim Basin

As worldwide hydrocarbon exploration has extended from shallowly to deeply buried strata, reservoir quality has attracted substantial and persistent interest in petroleum geology. In particular, deeply buried strata (>5500 m) in the Tarim Basin have attracted considerable attention because carbonate reservoirs that have experienced fracture or dissolution have also been shown to demonstrate considerable hydrocarbon potential. Therefore, it is necessary to determine how these reservoirs are developed and distributed in detail from both scientific and practical standpoints.In this paper, we address this issue using a case study in the southern Tahe area, which is contained within the largest Palaeozoic marine oilfield in China. In the northern Tahe area, mega-paleokarst systems developed in the Ordovician strata; however, the reservoir quality in the southern part of the Tahe area is relatively poor because it is covered by insoluble formations during karstification. Observations of cores and analyses of images of well logging demonstrate that these reservoirs are dominated by caves, vugs and fractures that have developed near faults. We speculate that the faults penetrating insoluble formations represent the main dissolution passages that originally developed these karstic fault systems. Additionally, we analyse a series of outcrops, seismic data, and structures to characterize the spatial geometry of these major faults and their surrounding fractures in detail. Most of these are strike-slip faults, and their subsequent reservoirs can be divided into three categories based on their development, including dendritic, sandwich and slab reservoirs. Recent studies demonstrate that karstic fault reservoirs are most common traps in the study area. Although various types of carbonate karstic fault reservoirs are represented in this region, the dendritic karstic fault reservoir is the most hydrocarbon-rich.Guided by these initial results, 108 wells were drilled from 2013 to 2014, producing 485 thousand tons of oil and yielding success ratios greater than 89%. The average production of dendritic reservoirs is 37.4 tons per day (t/d), while those of sandwich and slab types are 20.2 t/d and 14.0 t/d, respectively. These results represent significant references for future hydrocarbon exploration and the development of similar deeply buried karstic fault reservoirs in the Tarim Basin and elsewhere.     

珠三坳陷阳江凹陷构造特征及其对油气成藏的影响

在对研究区地震资料精细解释的基础上,对原阳江凹陷及其南缘低凸起重新进行了构造单元划分。阳江低凸起北支将原阳江凹陷分隔为阳江东、西两个凹陷,阳江东凹陷可以进一步分为东1洼和东2洼。阳江北断裂是阳江东、西两个凹陷主要的控凹断裂,根据断裂走向拐点和阳江东、西凹陷的分界可以把阳江北断裂划分为3段,分别是西段、中段和东段,西段控制阳江西凹陷,中段控制东1洼,东段控制东2洼。断裂各段活动规律不同,其中断裂中段控制的东1洼的主要活动期在晚始新世和早渐新世,控制文昌组和恩平组的湖相沉积,勘探潜力最好。继承、叠加发育的伸展构造样式是阳江东、西两凹陷的主要构造样式,断层型圈闭和披覆背斜型圈闭是该地区发育的主要圈闭类型。勘探实践表明,垂向运移和近源成藏是阳江东、西两凹陷主要的成藏规律。     

莱州湾地区郯庐断裂带的构造特征及其新生代演化

郯庐断裂带中段分东西两支从莱州湾进入渤海,在莱州湾地区的构造特征与演化历史一直鲜为人知。通过对横穿研究区的两条地震测线的解释和分析,揭示了该区郯庐断裂带中段在研究区的构造差异,研究表明郯庐断裂带东西两支在该研究区表现出不同的断裂性质,西支断裂表现为正断层,东支断裂表现为走滑断层。郯庐断裂是本研究区的主控断裂,通过对本地区地层形态及其组合、断层的剖面形态和空间展布规律的深入研究,揭示了郯庐断裂带在莱州湾地区新生代以来的构造演化历史:古新世—始新世的伸展阶段、渐新世—中新世早期的挤压和右行走滑阶段、中新世中晚期至今的稳定发展阶段,这几个不同时期的演化阶段主要受太平洋板块运动的方向和速度变化的控制。     

平湖油气田主断裂西部烃源评价及油源对比

平湖油气田主力含油气区位于平湖主断裂以东区域,油源主要来源于东部生烃凹陷的半封闭海湾暗色泥岩和煤层.公司于2011年11月在主断裂西部钻了一口探井XY井,目的是为探测主断裂西部含油气情况,扩大油气储量.结果钻遇油气层12m,测试获日产气14.66×104m3,日产油107.8 m3,取得了一定突破.为进一步评价西部含油气规模,钻后进行了油源对比研究,认为西部的油气主要是东部运移聚集的结果,西部源岩也有一定贡献.西部有形成一定规模油气藏的潜力.     

琼东南盆地深水区东区凹陷带结构构造及其演化特征

琼东南盆地深水区东区凹陷带,即松南—宝岛—长昌凹陷,位于琼东南盆地中央坳陷东端。在大量地震资料解释的基础上,对38条主要断层进行了详细分析。获得以下认识:(1)琼东南盆地深水区东区凹陷带平面上表现为近EW向展布的平行四边形,剖面结构表现为自西向东由半地堑—不对称的地堑—半地堑有规律变化。(2)琼东南盆地深水区东区凹陷带断裂系统可划分控制凹陷边界断层、控制洼陷沉积中心断层和调节性断层3类。(3)琼东南盆地深水区东区凹陷带古近纪时期受到太平洋板块俯冲和南海海盆扩张的双重影响,构造应力场发生NW—SE→SN转变。构造演化可划分为3个阶段:~32 Ma,应力场以区域性NW—SE向伸展为主,断裂系统以NE—SW向为主,控制凹陷边界;32~26 Ma,以南海海盆近SN向拉张应力场为主,断裂系统以NWW—SEE向为主,断层活动控制凹陷沉积中心;26~ Ma,区域性伸展与南海海盆扩张应力均逐渐减弱,NE—SW向和NWW—SEE向断裂继承性发育。(4)琼东南盆地深水区东区凹陷带内部主要断层在渐新统崖城组和陵水组沉积时期活动速率快,地形高差大、沉积水体深、沉积厚度大,控制了崖城组和陵水组的大规模沉积,有利于烃源岩的发育。圈闭以受断层控制的断鼻和断块为主,长昌主洼凹中隆起带发育2个最为理想的构造圈闭。     

斑岩Cu-(Mo-Au)矿床的成矿构造环境及勘查意义

斑岩矿床是重要的矿床勘查目标。斑岩矿床的成矿构造环境研究有助于确定斑岩矿床的战略勘查方向。斑岩矿床形成的成矿构造环境包括板块汇聚边缘、大陆转换板块边界、陆内造山环境和非造山环境。本文重点对斑岩矿床在汇聚边缘和大陆转换板块边界的成矿构造环境及其勘查意义进行初步总结。构造变化对斑岩矿床的形成起到触发作用。微弱和中等程度的转换挤压应力最有利于岩浆的集聚、上升和就位。岩浆侵入可以是在广阔的转换挤压断层带内或在其周围局部呈引张的地区集中出现。对于斑岩矿床战略勘查方向而言,应注意研究区域走滑断层与侵入体的关系,加强对地表浅部喷气蚀变的识别。在我国西南地区已勘查发现的5个斑岩成矿带中,应注意沿区域走滑断裂构造方向开展找矿。从成矿构造环境与哀牢山-红河构造带对比来看,鲜水河-小江断裂带可能是西南地区新的斑岩矿床勘查区。     

任楼矿井72煤层断层构造分形特征研究

利用分形理论,对安徽皖北任搂煤矿72煤层断层分形特征进行了研究,计算了不同构造分区的维数。研究发现构造复杂性不同及断裂性质的不同其分形维数也有所不同,构造简单,断层分维数小,而构造复杂区,断层分为数相对较大;剪切断裂带具有较低的分维值,张扭性断裂带分维值较高。     

激光雷达测量技术在地学中的若干应用

对激光雷达测量技术在全球冰川监测、局部断裂带提取、滑坡监测和稳定性评价以及海岸线提取和海岸侵蚀等方面的应用做了较为全面的综述.作为一种新型的对地观测手段,激光雷达(含星载、机载、车载和地面)的应用已经从传统的测绘扩大到包括文物保护在内的诸多其他应用领域.所综述的激光雷达技术在地学研究中的4个应用方面,是传统地学研究中与全球变化和人居环境最为密切的方向.分析表明,激光雷达技术在这些研究方向中的应用大有作为.      

南海北部深水区新生代岩浆岩分布规律及其与海底地质灾害的相关性

前人对南海北部新生代陆缘盆地结构、构造样式和期次等做了大量的研究工作,但对于具体体现内动力过程的岩浆活动关注较少,尤其是北部深水区的研究鲜有涉及。本文基于二维地震剖面的解译分析,将南海北部新生代岩浆岩划分为3个集中分布区:琼东南-西沙区、神狐区和东沙区。各区域岩浆岩的产出状态有所差异,其中琼东南-西沙区岩浆岩的平面展布规律性极强,主要受右行右阶的走滑断裂控制;神狐区岩浆岩位于NW向与NE向断裂的交汇处,侵位空间受先存断裂制约;东沙区岩浆岩的产生与东沙运动期间区域伸展过程有直接关系。作为内动力的表征,岩浆作用对于海底地形地貌具有重要的改造作用,与活动断裂、海底滑坡、浅层气等海底地质灾害也具有成因上的关联。     

The influence of differential sedimentary loading and compaction on the development of a deltaic rollover

Three-dimensional seismic data and wireline logs from the western Niger Delta were analyzed to reveal the sedimentary and tectonic history of a major deltaic growth-fault depocenter comprising a kilometer-scale rollover anticline. The seismic units of the rollover show a non-uniform thickness distribution with their respective maximum near the main bounding growth-fault on the landward side of the system. This wedge-shaped sediment-storage architecture ultimately reflects the non-uniform creation of accommodation space in the study area that was controlled by 1) the differential compaction of the hanging-wall and footwall strata, 2) the lateral variation of fault-induced tectonic subsidence above the listric master fault, and possibly 3) local subsidence related to the subsurface movement of mobile shale reacting to loading and buoyancy. A sequential three-dimensional decompaction of the interpreted deltaic rollover units allowed to reconstruct and measure the compaction development of the rollover succession through time, documenting that sediment compaction contributed per depositional interval to between 25 and 35% of the generation of depositional space subsequently filled by deltaic sediments. The incremental decompaction of sedimentary units was further used to quantify the cumulative amount of accommodation space at and around the studied rollover that was created by fault movement, shale withdrawal, regional tectonic subsidence, isostasy and changes in sea level. If data on the regional subsidence and eustasy are available, the contribution of these basinwide controls to the generation of depositional space can be subtracted from the cumulative accommodation balance, which ultimately quantifies the amount of space for sediments to accumulate created by fault movement or shale withdrawal. This observation is important in that it implies that background knowledge on subsidence, stratigraphic age and sea-level changes allows to reconstruct and quantify fault movement in syn-tectonic deltaic growth successions, and this solely based on hanging-wall isopach trends independent of footwall information.