Origin, hydrocarbon accumulation and oil-gas enrichment of fault-karst carbonate reservoirs: A case study of Ordovician carbonate reservoirs in South Tahe area of Halahatang oilfield, Tarim Basin

Based on comprehensive analysis of tectonic and fault evolution, core, well logging, seismic, drilling, and production data, the reservoir space characteristic, distribution, origin of fault-karst carbonate reservoir in Yueman block of South Tahe area, Halahatang oilfield, Tarim Basin, were studied systematically. And the regular pattern of hydrocarbon accumulation and enrichment was analyzed systematically based on development practice of the reservoirs. The results show that fault-karst carbonate reservoirs are distributed in the form of "body by body" discontinuously, heterogeneously and irregularly, which are controlled by the development of faults. Three formation models of fault-karst carbonate reservoirs, namely, the models controlled by the main deep-large fault, the secondary fault and the secondary internal fault, are built. The hydrocarbon accumulation and enrichment of fault-karst carbonate reservoirs is controlled by the spatiotemporal matching relation between hydrocarbon generation period and fault activity, and the size and segmentation of fault. The study results can effectively guide the well deployment and help the efficient development of fault-karst carbonate reservoirs of South Tahe area, Halahatang oilfield.

Types,Characteristics and Significances of Migrating Pathways of Gas-bearing Fluids in the Shenhu Area,Northern Continental Slope of the South China Sea

The first marine gas hydrate expedition in China has been conducted by Guangzhou Marine Geological Survey in the Shenhu Area, northern continental slope of the South China Sea. Previous study has analyzed the P-T conditions, geophysical anomalies and saturation calculations of these gas hydrates, but has not documented in detail the migration of gas-bearing fluids in the study area. Based on the interpretations of 2D/3D seismic data, this work identified two types of migration pathways for gas-bearing fluids in the Shenhu area, i.e., vertical and lateral pathways. The vertical pathways（largescale faults, gas chimneys and mud diapirs） presented as steep seismic reflection anomalies, which could be traced downward to the Eocene source rocks and may penetrate into the Late Miocene strata. The deeper gases/fluids might be allowed migrating into the shallower strata through these vertical conduits. However, the distributions showed distinct differences between these pathways. Large-scale faults developed only in the north and northeast of the Shenhu area, while in the drilling area gas chimneys were the sole vertical migration pathways. Since the Pliocene, normal faults, detachment faults and favorable sediments have constituted the lateral pathways in the Shenhu gas hydrate drilling area. Although these lateral pathways were connected with gas chimneys, they exerted different effects on hydrate formation and accumulation. Gas-bearing fluids migrated upward along gas chimneys might further migrate laterally because of the normal faults, thereby enlarging the range of the chimneys. Linking gas chimneys with the seafloor, the detachment faults might act as conduits for escaping gases/fluids. Re-deposited sediments developed at the early stage of the Quaternary were located within the gas hydrate stability zone, so hydrates would be enriched in these favorable sediments. Compared with the migration pathways（large-scale faults and mud diapirs） in the LW3-1 deep-sea oil/gas field, the migration efficiency of the vertical pathways（composed of gas chimneys） in the gas hydrate drilling area might be relatively low. Description and qualitative discrimination of migration pathways in the Shenhu gas hydrate drilling area are helpful to further understand the relationship between good-quality deep source rocks and shallow, mainly biogenicallyproduced, hydrates. As the main source rocks of the Baiyun sag, lacustrine mudstones in the Wenchang and Enping Formations may provide thermogenic methane. Gas chimneys with relatively low migration efficiency created the vertical pathways. Caused by the Dongsha tectonic movement, the release of overpressured fluids might reduce the vertical migration rates of the thermogenic methane. The thick bathyal/abyssal fine-grained sediments since the Late Miocene provided migration media with low permeability. These preconditions may cause carbon isotopic fractionation ofthermogenic methane during long-distance vertical migrations. Therefore, although geochemical analyses indicate that the methane forming gas hydrate in the Shenhu area was mainly produced biogenically, or was mixed methane primarily of microbial origin, thermogenic methane still contribute significantly.

Identification methods of coal-bearing source rocks for Yacheng Formation in the western deepwater area of South China Sea

Owing to the fact that the coal-beds are with the characteristics of multi-beds, thin single-bed, rapid lateral changes and deep burial, coal-bearing source rocks are difficult to be identified and predicted, especially in the lower exploration deepwater area. In this paper, a new integrative process utilizing geology and geophysics is proposed for better predicting the distribution of coal-bearing source rocks. Coal-beds were identified by the logging responses of“three higher, three lower, and one expand”and carbargilite were recognized by the characteristics of“four higher and one lower”. Based on the above logical decision, coal-beds and carbargilite can be distinguished automatically by cluster analysis of logging curves in verticality. Within the constraints of well-seismic calibration, the coal-beds group also can be detected in horizontality by the integrated representation of“negative phase, higher Q, lower impedance and lower frequency”within the seismic data. However, the distribution of coal-bearing source rocks utilizing geophysical methodology may do not conform to the geological rules of coal accumulation. And then the main geological controlling factors of coal accumulation are comprehensively analyzed as follows：（1） Paleotopography and tectonic subsidence determine the planar range of terrestrial-marine transitional facies markedly;（2） The relative sea level changes affect the accommodation space and shoreline migration, and limit the vertical range of coal-beds. More specifically, the relationship between the accommodation creation rate and the peat accumulation rate is a fundamental control on coal accumulation. The thickest and most widespread coals form where those two factors reached a state of balance;（3） The supply of autochthonous clasts and the distance between deposition places and paleovegetation accumulated area are the critical factor to form abundant coal, which means that if deposition area is close to paleouplift, there would be sufficient organic matters to form abundant source rocks. The results show that the integrated methods can significantly improve prediction accuracy of coal-bearing source rocks, which is suitable for early exploration of western deepwater area of South China Sea.

Structural Styles of Fronts of Thrust-Detachment Faults in Petroleum-bearing Areas of Western China

The front of a thrust-detachment fault may have various styles such as decoupling, fold, forethrust and backthrust ones because of differences in magnitude, direction and time of the forces exerted on the fault and the inhomogeneity of rock mechanical properties. They have different characteristics and are usually associated with gravity structure, inverse structure and diapir structure. These structures exist together in the same thrust-detachment fault and can influence, compensate for and convert into each other. They provide important grounds not only for the study of the dynamic state, propagation mode, evolutionary process and formation mechanism but also for the analysis of the petroleum generation, migration, accumulation and preservation and arrangement of drill holes in foreland basins.

GEOTECTONIC BACKGROUND OF PYROPHYLLITE MINERALIZATION AND ORE-BEARING VOLCANIC FORMATION IN SOUTHEASTERN COASTAL AREAS,CHINA

The volcanic gas-liguid type of pyrophyllite deposits in the SoutheasternCoastal areas, China are the product of tectono-magama-volcanism in Diwa regions. The pyro-phyllite ore-bearing volcanic formation were formed in the maximum-mobility period of Diwa, which are mainly the Late Jurassic strata and are secondly the Early Cretaceous volcanic-sedi-mentary rock series strata. The lithology of the host rock is mainly rhyolitic crystal-vitric tuff, and the chemical composition is characterized by high silicon rich alumium and low iron, be-longing to the acid-intermediate-acid rock and the kalicalc-calc-alkalic series and the rhyo-lite-rhyodacite assemblage. They play an important role in the pyrophyllite mineralization.

CORRELATION BETWEEN THE TERTIARY STRATA IN OIL-GAS-BEARING AREAS OF CHINA AND THE TYPICAL SEQUENCE IN EUROPE AND AMERICA

The Tertiary strata in oil-gas-bearing areas of China are mainly composed of continental deposits, with only a few marine deposits in Xinjiang, Taiwan and the southeast sea region. In the widespread Tertiary, a large amount of oil-gas pools have been found. Consequently, it is necessary to draw up a stratigraphical correlation table of the Tertiary

Exploration Technology for Complex Sandstone Reservoirs in the Developed Area of Shengli Oilfield

Jiyang depression, which is the main oil productive area of Shengli oil field, is located at the southeast part of the Bohai Bay Basin and is a terrestrial lacustrine rift subsidence basin formed in the late Mesozoic with fully developed fault system. The main hydrocarbon productive formations of this depression are the terrestrial clastic rocks of the Tertiary, which are of strong lateral variation. The complex fault reservoirs and subtle lithological reservoirs distributed extensively and are becoming the main exploration targets in recent years. The exploration and development practice in these years has formed the exploration technologies, mainly including detailed study and description of low grade faults, delineation of microstructures, facies constrained formation description and prediction and low resistivity oil bearing formation’s identification. These exploration technologies have resulted in remarkable effectiveness on the reserve and oil production increments.

Suitability evaluation and spatial capacity analysis for complex topography construction land area in southwest China:a case study of Tongzi county in Guizhou province

In the background of a new round reform and western development strategy, making suitability evaluation of construction land complex topography area in southwest China scientifically and accurately has an important guiding significance on the construction of local urban and rural development. We selected economic factor of construction, safety factor of construction, factor of the present situation of land use and ecological protection factor in Tongzi county as evaluation indexes, and ascertained the weight of each elastic indicator using the analytic hierarchy process method. By the support of GIS and RS technology, we combined the single-factor qualitative classification with the multi-factor weighted overlay analysis to make comprehensive suitability evaluation of construction land on the whole study area. And five different types of construction land were divided, namely, ‘excellent', ‘very good', ‘good', ‘moderate' and ‘poor'. The result shows that the area of ‘excellent' construction land is 30.47 km^2(0.95%), 101.46 km^2(3.16%) of ‘very good', 550.34 km^2(17.16%) of ‘good', and 664.69 km^2(20.72%) and 1 860.65 km^2(58.01%) of ‘moderate' and ‘poor', respectively. The land space bearing capacity is a population of 791 600, and the remaining population capacity is 170 900 persons.

不同溶洞处治措施对桩基承载特性的影响研究

为探究不同溶洞处治措施对岩溶发育区桩基承载特性的影响,通过有限元软件建立溶洞-桩-岩土体耦合作用模型,对比分析溶洞高度变化情况下,2种不同的溶洞处治措施(回填法和钢护筒跟进法)对桩基承载特性的影响。结果表明:随着溶洞高度增加,2种处治措施下桩基竖向承载力都呈降低趋势;溶洞高度小于10 m时,不同处治措施对桩基竖向承载力影响可忽略,溶洞高度大于10 m则需考虑处治措施对桩基竖向承载力的影响;在回填法处治的溶洞范围内,桩身轴力降幅较大,桩侧摩阻力增加显著,在钢护筒跟进法处治的溶洞中桩身轴力与桩侧摩阻力则基本不变;与钢护筒跟进法相比,回填法更有利于发挥桩侧摩阻力;溶洞高度增加时,2种处治措施下桩侧摩阻力比重均逐渐减小,桩端阻力比重逐渐增大,达到桩基极限承载力时,回填法处治后的溶洞较钢护筒跟进法桩端阻力占整体比例更小。

大宝山含钨褐铁矿中钨的赋存状态与嵌布特征

通过多种分析方法,探究广东大宝山含钨褐铁矿的物相组成、元素分布等工艺矿物学特征,以揭示矿石中关键金属钨的赋存状态与嵌布特征。X射线荧光分析(XRF)、粉末X射线衍射(XRD)以及扫描电子显微镜和能谱(SEM-EDS)结果表明:矿石中主要矿物为含钨褐铁矿和石英,关键金属钨品位为1.35%。微区X射线衍射(Micro-XRD)和矿物解离度分析仪(MLA)结果表明:钨主要赋存于高铁钨华((W,Fe)(O,OH)_(3))中,而高铁钨华则以剥离和带状形式紧密分布在褐铁矿中。同时,还定量分析了有价元素在各主要矿物中的赋存和分布情况,并讨论了含钨褐铁矿风化演变和形成机制。最终提出了一种选冶联合分选回收流程,为高效回收含钨褐铁矿中关键金属钨提供理论基础。

平顶山矿区多煤层卸压立体抽采模式与工程示范

平顶山矿区多煤层发育、含气层段多,仅靠井下进行瓦斯治理工程量大、难度高。为了开辟平顶山矿区瓦斯抽采新模式,达到“采一层抽多层”的目的,采用气测录井与含气量测试相结合的方法精准判识了煤系主要含气层段和含气量;采用体积法评价了东部5对矿井采动区和采空区的煤系气资源量。基于“O”形圈理论和“防-抗-让”思想,分别优化设计了采动井、采空井的井位、层位和井身结构,构建了采动区、采空区多煤层卸压立体抽采模式并进行了工程示范。结果表明:(1)二_(1)煤层顶板200 m范围内存在四煤组、三煤组、二_(1)煤层顶板60 m范围内的砂岩/泥质砂岩互层段等3处主要含气段。平顶山矿区东部5对矿井的采动区和采空区资源量分别为26.36×10~8 m^(3)和20.00×10~8 m^(3)。(2)采动井最佳井位为0.17~0.28倍采长,且靠近回风巷条带区域;走向上,采动井的间距一般为80~100 m。创建了“大口径、避开岩体变形强烈区、P110梯型扣套管”的采动直井稳孔技术体系和“下行水平轨迹+提高套管强度”的采动L型水平井稳产技术体系,保证了产气通道的畅通性。采空井一般布置在距离回风巷30~50 m的区域,完钻位置一般为二_(1)煤层顶板40~60 m的范围;筛管布置在四煤段顶板至裂隙带底部。(3)建立了“地面采动直井/定向井-采动L型水平井-采空井”联作的卸压立体抽采模式,实现了多气源立体抽采。截至2024年4月30日,累计抽采纯量达5258.8万m^(3),总利用量达到3735.4万m^(3),率先在河南省实现了煤系气产业化开发,示范和引领带动作用显著。

河南平顶山矿区含煤地层沉积环境及其对煤系气成藏的控制

近几年来,河南省平顶山矿区煤系气勘探开发取得了新突破,采动井、采空井和预抽井的单井日抽采量分别达到40500 m^(3)、20000 m^(3)和4500 m^(3)。为了查明煤系气生成与赋存的沉积背景,本次工作采用地层学与沉积学的研究方法,开展了精细的地层、沉积特征和沉积序列以及气测录井资料分析,从而揭示出本区主要含煤地层山西组和下石盒子组中煤系气(煤层气、页岩气和致密砂岩气)生成与赋存的沉积环境,也就是潮坪上的泥炭沼泽(泥炭坪)、三角洲分流间湾沼泽和分流河道沉积环境控制了煤系气的成藏。基于地层沉积特征在垂向上的变化规律,划分出9种不同沉积环境的沉积序列类型,并在综合分析的基础上,提出了平顶山矿区山西组—下石盒子组煤系气赋存的沉积环境模式。研究还表明,区内煤系气含量变化及区域分布特征不仅与滨岸潮坪沼泽、三角洲分流河道砂体和分流间湾沼泽的时空变化密切相关,而且还与储集层厚度变化相关。该成果可为今后平顶山地区煤系气勘探开发井的设计、部署与施工提供科学依据。同时,对华北地区相同含煤地层的煤系气开发也具有重要借鉴意义。

动车前端承载结构拓扑优化及车体动态承载极限分析

使用OptiStruct软件,对车体前端承载结构进行拓扑优化,以体积分数为约束,以最小应变能作为优化目标,通过优化结果对车体前端骨架结构进行重新排布。对优化后的车体在车钩安装座、前端吸能结构及防爬器三个不同位置加载,完成刚性墙对车体冲击过程仿真。对车体在冲击过程中冲击力-时间曲线和不同时刻应力分布进行分析,得到车体弱刚度区域,通过应力变化临界点确定车体承载极限。对弱刚度区域不同组件的能量-时间曲线与上述承载极限结果进行验证。结果表明,优化后车体前端刚度大幅提升;在车体承载极限内,不同位置加载对车体承载极限影响较小;通过弱刚度区域各不同组件的能量-时间曲线可以准确地找到车体承载极限达到临界点的时刻,为车体动态承载极限提供数据分析。

华北赋煤区地热资源富集模式及开发利用方向

【目的】中国是煤炭大国,在煤炭行业迫切需要转型的形势下,研究赋煤区的地热资源成因与分布规律十分必要。华北赋煤区地热资源储量占全国的74.7%,是中国地热资源最富集的区域之一。区内分布有渤海湾盆地、鄂尔多斯盆地、沁水盆地和南华北盆地等主要含煤盆地,其岩石圈热状态自东向西逐步降低。地热储包括新生界砂岩孔隙型和寒武-奥陶系碳酸盐岩岩溶-裂隙型两大类型。碳酸盐岩岩溶-裂隙热储温度高、水量大、易于回灌,是煤田区地热勘查与开发利用的优先选择。【方法】针对煤田区地热地质的特点,开展地热系统动力学分析,优选华北赋煤区的地热勘查与开发区域。【结果和结论】提出煤田区有以下4种聚热模式:(1)煤层与碳酸盐岩地层储盖组合传导聚热;(2)基岩面起伏变化传导聚热;(3)断裂带地下水活动对流聚热;(4)碳酸盐岩基岩面风化壳岩溶以及侵入体接触面岩溶对流聚热。并结合实例进行数值模拟分析。在此基础上,指出华北赋煤区地热勘查与开发优先方向是深部碳酸盐岩储层中的地热资源。地热能作为非碳基能源之一,以其储量大、清洁、输出连续的特点,在未来社会对电力、燃料和热力三大能源需求中的热力供应方面尤其可以做出重要贡献,而中国地热与煤炭资源在空间分布上的重叠,使地热开发利用成为煤炭行业转型的有效途径之一。

四川盆地中部地区震旦系大型碳酸盐岩气藏开发技术新进展

四川盆地中部地区(以下简称川中地区)震旦系灯影组气藏为大型古老深层岩溶风化壳型碳酸盐岩气藏,气藏整体表现为低孔隙度低渗透率,储集空间小尺度缝洞发育,储层非均质性强特征,气藏开发面临储层表征难、井位部署和效益开发难度大等系列挑战。为此,以川中地区安岳气田灯影组气藏为对象,通过地质工程一体技术化攻关,深化了对储层发育特征和成因机理的认识,提出了气藏开发新模式,创建形成了气藏高效开发的关键技术。研究结果表明:①灯影组储层主要为岩溶成因储层,具有“叠合岩溶差异控储”的发育特征;②岩溶储层非均质性强,“溶蚀相成因控储”可精细刻画储层的非均质性;③灯影组气藏宜采用“单井指标叠加论证气藏规模”的开发新模式;④创新形成了“双界面”岩溶古地貌恢复及定量刻画方法,并指导平面选区,其中Ⅰ+Ⅱ类井比例由评价期的40%提高到方案建设期的100%;⑤创建了小尺度缝洞识别、刻画及表征技术,并指导钻井轨迹设计,测试百万立方米气井比例由开发评价期的41.6%提高到建产期的60%;⑥配套完善了分段酸压工艺技术,高效动用了优质储层,并解放了低品位储层,储层渗透率由改造前的0.62 mD提高到酸压改造后的6.77 mD。结论认为,“十四五”期间,在上述开发技术的支持下,安岳气田由台缘带灯四段高效开发转向长期稳产和台内地区多层系效益开发,蓬莱含气区由单井高产转向区块高产和气藏规模建产,将强力支撑中国石油西南油气田公司“十四五”末天然气上产500×10^(8)m^(3)。

高烈度区长联PC连续梁桥减隔震措施分析

为了明确高烈度区长联预应力混凝土(prestressed concrete,PC)连续梁桥滑动摩擦摆式支座的减隔震性能,针对设防烈度为9度的某长联PC连续梁桥,利用CSiBridge软件建立大桥空间梁单元非线性分析模型,以普通球型钢支座地震响应为基准,对比分析铅芯橡胶支座与滑动摩擦摆式支座的减隔震性能,并对滑动摩擦摆式支座的摩擦系数和支座曲率进行参数分析。结果表明:在长联连续梁桥中,相比于铅芯橡胶支座,滑动摩擦摆式支座减隔震效果更好,固定墩内力与变形更小,全桥受力更加均匀合理;对于滑动摩擦摆式支座,摩擦系数越大,长联连续梁固定墩墩底弯矩与墩顶位移越大,摩擦系数变化20%,固定墩墩底弯矩最大值变化约1.67%,墩顶位移极值变化约1.45%;支座曲率半径对长联连续梁地震响应的减隔震性能影响较小,曲率半径增大1.5 m,固定墩墩底弯矩最大值增大约0.97%,固定墩墩顶位移增幅约为0.37%~1.39%。

鄂尔多斯盆地陇东地区长8油层组物源分析

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岩溶区桩基承载特性研究综述

在岩溶区进行桩基施工时,应尽可能地避开溶洞,但不可避开的情况也普遍存在,因此岩溶区桩基承载特性研究是桩基发展过程中必须要面对的问题。从理论研究、物理实验、数值模拟3个方面对岩溶区桩基承载特性研究现状进行了分析,得到如下结论:现有承载力计算公式存在影响因素考虑不全的情况,后续理论研究应考虑多因素协同影响下单桩极限承载力计算公式推导。物理模型试验的变量较为单一,试验过程中常常忽略水对桩基承载特性的影响,后续研究应当重点考虑地下水及多因素的协同作用。原位实验开展较少,检测获得数据准确性有待提高,后续应开展更多的原位实验、现场破坏实验以获得更全面的桩基承载特性实验数据。数值模拟研究中溶洞模型的建立大多采用长方体、正方体、椭球体、球体等标准尺寸,这与实际地层溶洞三维几何尺寸不符,真实的溶洞几何模型的建立是未来重点的发展方向。

龙凤山气田易漏井不承压泡沫水泥浆固井技术

中国石化龙凤山地区面临井温高、地层承压能力低、周期长、承压堵漏成本高等系列固井技术难题,导致固井周期长、费用高且固井质量无法保证等。为解决上述问题,在分析工区现有固井工艺的基础上,提出了不承压泡沫水泥浆固井设计思路,形成了龙凤山地区不承压泡沫水泥浆固井工艺,建立了泡沫水泥浆井内密度及恒密度注气固井计算方法与固井工艺;优选了发泡剂、降失水剂和早强剂等泡沫水泥浆关键外加剂,开发了新型低密度泡沫水泥浆体系,耐温性可达到120℃以上,泡沫半衰期大于420 s、水泥浆30 min失水32 mL、48 h强度13.3 MPa,各项性能均可满足中石化龙凤山气田高温、深井固井要求;形成了适合于龙凤山气田泡沫水泥浆固井技术。现场11口井应用表明,该项技术能够有效提高固井质量,避免了固井前承压、分级或尾管固井作业,平均节约承压堵漏周期7 d以上,经济效益显著。龙凤山气田泡沫水泥浆固井技术对解决中国石化其他工区深井、高温井固井漏失、承压堵漏等难题具有重要借鉴意义和可持续性推广价值。