Geochemical characteristics and genetic model of dolomite reservoirs in the eastern margin of the Pre-Caspian Basin

The widespread Carboniferous KT-I dolomite in the eastern margin of the Pre-Caspian Basin is an important hydrocarbon reservoir. The dolomite lithology is dominated by crystalline dolomite. The δ18O values range from -6.71‰ to 2.45‰, and average 0.063‰, obviously larger than -2.5‰, indicating low-temperature dolomite of evaporation origin. Stable strontium isotope ratios （87Sr/86Sr） range from 0.70829 to 0.70875 and average 0.708365, very consistent with 87Sr/86Sr ratios in Carboniferous seawater. Chemical analysis of Ca and Mg elements shows that the dolomite has 9.1 mole% excess Ca or even higher before stabilization. The degree of order of dolomite is medium–slightly poor, varying in a range of 0.336-0.504 and averaging 0.417. It suggests that the dolomite formed under near-surface conditions. There are two models for the origin of the Carboniferous KT-I dolomite reservoir. These are 1） the evaporation concentration – weathering crust model and 2） the shoal facies – seepage reflux model. The former is mainly developed in restricted platforms – evaporate platforms of restricted marine deposition environments with a representation of dolomite associated with gypsum and mudstone. The latter mainly formed in platform edge shoals and intra-platform shoals and is controlled by dolomitization due to high salinity sea water influx from adjacent restricted sea or evaporate platform.

Application of the Material Balance Method in Paleoelevation Recovery: A Case Study of the Longmen Mountains Foreland Basin on the Eastern Margin of the Tibetan Plateau

We applied the material balance principle of the denudation volume and sedimentary flux to study the denudation-accumulation system between the Longmen Mountains （Mts.） and the foreland basin. The amount of sediment in each sedimentation stage of the basin was estimated to obtain the denudation volume, erosion thickness and deposit thickness since the Late Triassic Epoch, to enable us to recover the paleoelevation of the provenance and the sedimentary area. The results show the following： （1） Since the Late Triassic Epoch, the elevation of the surface of the Longmen Mts. has uplifted from 0 m to 2751 m, and the crust of the Longmen Mts. has uplifted by 9.8 km. Approximately 72% of the materials introduced have been denuded from the mountains. （2） It is difficult to recover the paleoelevation of each stage of the Longmen Mts. foreland basin quantitatively by the present-day techniques and data. （3） The formation of the Longmen Mts. foreland basin consisted of three stages of thrust belt tectonic load and three stages of thrust belt erosional unload. During tectonic loading stages （Late Triassic Epoch, Late Jurassic-Early Cretaceous, Late Cretaceous-Miocene）, the average elevation of Longmen Mts. was lower （approximately 700-1700 m）. During erosional unloading stages （Early and Middle Jurassic, Middle Cretaceous and Jiaguan, Late Cenozoic）, the average elevation of Longmen Mts. was high at approximately 2000-2800m.

Crustal Uplift in the Longmen Shan Mountains Revealed by Isostatic Gravity Anomalies along the Eastern Margin of the Tibetan Plateau

This study examines the relationship between high positive isostatic gravity anomalies （IGA）, steep topography and lower crustal extrusion at the eastern margin of the Tibetan Plateau. IGA data has revealed uplift and extrusion of lower crustal flow in the Longmen Shan Mountains （the LMS）. Firstly, The high positive IGA zone corresponds to the LMS orogenic belt. It is shown that abrupt changes in IGA correspond to zones of abrupt change of topography, crustal thickness and rock density along the LMS. Secondly, on the basis of the Airy isostasy theory, simulations and inversions of the positive IGA were conducted using three-dimensional bodies. The results indicated that the LMS lacks a mountain root, and that the top surface of the lower crust has been elevated by 11 km, leading to positive IGA, tectonic load and density load. Thirdly, according to Watts＇s flexural isostasy model, elastic deflection occurs, suggesting that the limited （i.e. narrow） tectonic and density load driven by lower crustal flow in the LMS have led to asymmetric flexural subsidence in the foreland basin and lifting of the forebulge. Finally, based on the correspondence between zones of extremely high positive IGA and the presence of the Precambrian Pengguan-Baoxing complexes in the LMS, the first appearance of erosion gravels from the complexes in the Dayi Conglomerate layer of the Chengdu Basin suggest that positive IGA and lower crustal flow in the LMS took place at 3.6 Ma or slightly earlier.

Paleoseismological Study of the Late Quaternary Slip-rate along the South Barkol Basin Fault and Its Tectonic Implications,Eastern Tian Shan,Xinjiang

The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Quaternary activity, paleoseismology, and deformation characteristics of the fault provide important clues for understanding the tectonic process of the eastern Tian Shan orogen and implementing seismic mitigation. Through interpretation of high-resolution satellite images, unmanned aerial vehicle measurements, and detailed geological and geomorphic investigations, we suggest that the fault exhibits clear left-lateral slip along its western segment. Paleoseismic trenches dug near Xiongkuer reveal evidence of six large paleoearthquakes. The four latest paleoearthquakes were dated： the oldest event occurred at 4663 BC–3839 BC. Data on the horizontal offsets along the probable 1842 Barkol earthquake coseismic rupture suggest clear multiple relationships between cumulative offsets and possible ~4 m of coseismic left-lateral slip per event. From the cumulative offsets and 14 C sample ages, we suggest an average Holocene left-lateral slip rate of 2.4–2.8 mm/a on the SBF, accounting for ~80% of lateral deformation within the entire eastern Tian Shan fault system. This result is comparable with the shortening rate of 2–4 mm/a in the whole eastern Tian Shan, indicating an equal role of strike-slip tectonics and compressional tectonics in this orogen, and that the SBF may accommodate substantial lateral tectonic deformation.

The Coupling Relationship between the Uplift of Longmen Shan and the Subsidence of Foreland Basin,Sichuan,China

Depending on the analysis of the coeval sedimentary geometry and subsidence mechanism in the Longmen Shan foreland basin, three models about the coupling relationship between Longmen Shan uplift and foreland basin subsidence since the Indosinian have been proposed：（1） crustal shortening and its related wide wedge-shaped foreland basin,（2） crustal isostatic rebound and its related tabular foreland basin, and（3） lower crustal flow and its related narrow wedge-shaped foreland basin. Based on the narrow wedge-shaped foreland basin developed since 4 Ma, it is believed that the narrow crustal shortening and tectonic load driven by lower crustal flow is a primary driver for the present Longmen Shan uplift and the Wenchuan（Ms 8.0） earthquake.

青藏高原东缘及邻区强震构造:专辑序言

青藏高原东缘由多个次级构造单元组成了独特的“多层次挤出-旋转活动构造体系”,是调节高原物质向东挤出的构造转换带,发育了高密度的活动断裂,强震频度高且强度大,而且地质地貌复杂,成为我国地震灾害问题最为突出的地区之一。近年来,伴随全国地震灾害风险普查、城市活断层探测、地震科学实验场建设、工程场地的地震安全性评价以及重大工程与城镇区的活断层鉴定与地壳稳定性评价等工作的深入开展,高精度遥感、构造地貌、古地震和第四纪年代学等方法的广泛应用,显著提升了青藏高原东缘及邻区强震构造的调查研究程度。为了及时交流这方面的最新研究成果,支撑区域防震减灾及重要工程和基础设施建设的地质安全评价等工作,《地震科学进展》编辑部组织了“青藏高原东缘及邻区强震构造”成果专辑,征集了活断层与地震、甘肃积石山地震以及相关领域的研究综述等代表性学术论文20余篇,本期《青藏高原东缘及邻区强震构造专辑Ⅰ》优选了10篇论文,后续还将推出《青藏高原东缘及邻区强震构造专辑Ⅱ》,希望这些成果可提升对区域强震活动特征与孕震构造机制的理解,并为区域强震危险性分析和有效防范强震灾害风险提供科学依据。

鄂尔多斯盆地东缘奥陶纪马家沟期边界断层的新认识及其对成钾凹陷的控制

鄂尔多斯盆地陕北盐盆奥陶系马家沟组具备良好的成钾潜力,然而,当前仅勘探到薄钾石盐矿层和厚层钾石盐矿化段,大规模钾盐矿尚未发现。通过分析鄂尔多斯盆地东缘地震剖面的构造特征,认为盆地东缘晋西挠褶带西部马五6亚段沉积期存在活动边界正断层。在该断层作用下,形成东断西超的活动同沉积凹陷,富钾卤水大量汇聚于此。在持续干旱的强蒸发环境下,卤水持续浓缩,成钾窗口出现,钾石盐大规模析出,进而形成整装海相优质固体钾石盐矿床。侏罗纪末期,挤压应力导致成钾凹陷抬升,形成古凹今隆的格局,钾盐层抬升至较浅部位,有利于水溶法经济开采。

忻定盆地金山凸起东缘断裂展布及晚第四纪最新活动特征

通过野外地质地貌调查结合无人机航拍测量、地质雷达勘探及浅层地震勘探综合分析认为,金山凸起东缘断裂整体呈NE向展布,走向40°,北起忻口村一带,向SW经金山铺村西、前淤泥村西延伸至部落村以北,进而向SWS转折进入盆地区。经探槽开挖和年龄测试,该断裂段最新断错晚更新世早期地层。

滇东地区裂谷盆地内火山-侵入岩序列与金属成矿

碱性岩浆对金属成矿和金属矿集区有独特控制作用,因火山—侵入岩序列与金属成矿和岩浆叠加侵入构造系统识别难度大,长期制约了深部勘探和找矿预测。本文以云南东川铁铜金矿集区(元古宙陆缘裂谷盆地)和个旧锡铜钨铯铷多金属矿集区(三叠纪弧后裂谷盆地)为主,采用大比例尺构造岩相学填图新方法,解析研究了碱性岩浆活动有关的火山—侵入岩侵入序列与岩石组合、裂谷盆地演化和岩浆叠加侵入构造系统,揭示了它们与滇东地区铁氧化物铜金型(IOCG)、铜钴-金红石-稀土和锡铜钨铯铷多金属矿叠加成矿内在关系。研究认为:①云南东川铁铜金矿集区内,新太古代末期碱性岩类以方解石钠长岩(2520±14 Ma)和碱性铁质苦橄岩(2529±77 Ma)为主。新太古界—古元古界小溜口岩组(>2.50Ga)顶部古岩溶风化壳,受中元古代火山喷发—岩浆侵入构造叠加再造形成了特殊单元(独立填图单元,2.50~1.80Ga),它们是铜钴-金红石-稀土矿床的新找矿层位。②在中元古界因民组一段内,铁钠质碱性基性岩、铁钾质粗面岩和铁质碱性辉绿辉长岩等岩石组合形成于因民期火山断陷成盆期。因民组二段和三段是稀矿山式铁铜矿床储矿层位,铁铜矿层下盘铁钾质粗面岩为独居石型稀土成矿层位。在格林威尔造山期碱性钛铁质辉长岩(1097~1047 Ma)-碱性钛铁质闪长岩-碱性二长斑岩等碱性钛铁质侵入岩体,形成了白锡腊深部IOCG矿床和金红石富集成矿。③在个旧三叠纪弧后裂谷盆地内,三叠纪碱性苦橄岩和碱玄岩中形成了Sn-Cu-Zn-Li-Rb-Cs初始富集;在晚白垩世浅色花岗岩叠加成矿作用下,形成了金云母矽卡岩型锡铜钨铯铷矿床。④裂谷盆地内早期碱性岩中初始富集金属与后期富含成矿金属的碱性侵入岩叠加成矿可能是金属超常富集机理。在东川地区岩浆叠加侵入构造内,岩浆热液角砾岩筒对铜钴-金红石-稀土元素叠加富集成矿控制显著;在个旧地区,浅色花岗岩侵入于碱性苦橄岩-碱玄岩中,对金云母矽卡岩型锡铜钨钴铯铷矿床的叠加富集成矿控制显著。

Multi-Stage Basin Development and Hydrocarbon Accumulations： A Review of the Sichuan Basin at Eastern Margin of the Tibetan Plateau

Sichuan Basin is one of the uppermost petroliferous basins in China. It experienced three evolutionary phases which were marine carbonate platform （Ediacaran to Late Triassic）, Indosinian-Yanshanian orogeny foreland basin （Late Triassic to Late Cretaceous） and uplift and tectonic modification （Late Cretaceous to Quaternary）. The present-day tectonics of the Sichuan Ba- sin and its periphery are characterized by three basic elements which are topography, basement type and surface structure, and two settings （plate margin and interior）. Therefore, be subdivided into five units which have different structure and tectonic history. The basin contains five different sets of source rocks with thickness up to 2 500 m. These source rocks were well preserved due to the presence of Middel-Lower Triassic evaporites （〉-200 m） and thick terrestrial sediments filling in the Indosinian-Yanshanian foreland basin （〉3 000 m）. The uplift and erosion since Late Cretaceous has significant influence on cross-strata migration and accumulation of oil and gas. The multi-phase evolution of the basin and its superimposed tectonic elements, good petroleum geologic conditions and diverse petroleum systems reveal its bright exploration prospects.

四川盆地东缘寒武系盐下油气勘探领域探讨

地球物理资料显示四川盆地东缘齐岳山附近寒武系高台组膏盐岩层下深部存在逆冲构造,其形成过程以及油气地质意义未见深入研究。笔者等综合四川盆地东部石柱地区线束三维和建南地区二维地震反射资料,并结合钻井资料以及区域地质研究成果,从构造继承性的角度探讨四川盆地震旦系灯影组台缘带类型,并分析了川东地区寒武系盐下油气圈闭特征。研究获得如下认识:①川东齐岳山北段构造变形强烈,普遍发育基底卷入构造,构造样式受青白口纪—南华纪裂谷与转换带构造位置的控制。②依据构造继承关系将盆内灯影组台缘带划分为德阳—安岳地区原生型台缘带、万源—达州地区继承型台缘带以及石柱地区继承—改造型台缘带。③依据青白口纪—南华纪裂谷的分布和后期构造作用影响大小,认为沿齐岳山向南至南川一带存在与石柱地区相似的灯影组继承—改造型台缘带,忠县、南川以西存在灯影组继承型台缘带。④研究区新元古界—下寒武统烃源岩、灯影组—龙王庙组滩相白云岩储层与寒武系膏盐岩层系构成完整的生储盖组合。⑤寒武系盐下基底逆冲可形成成排、成带的构造,与灯影组继承—改造型台缘带、龙王庙组滩相白云岩储层配置,形成断层相关的构造—岩性圈闭带,成为川东地区油气规模聚集有利区。研究认为四川盆地东部石柱地区震旦纪—早寒武世早期继承了青白口纪—南华纪裂谷构造特征,燕山期构造反转,高台组盐下形成基底卷入逆冲构造,具备生储盖等基本石油地质条件,具有重要的油气勘探现实意义。

鄂尔多斯盆地东缘深部煤层气开发先导试验效果与启示

鄂尔多斯盆地东缘大宁-吉县区块深部煤层气勘探开发取得突破对煤层气产业带来重大影响,引起业内广泛关注和跟进。前期一些学者对深部煤层气勘探开发理论技术难点与对策开展了研究,但缺乏对典型气田开发先导试验系统总结。通过深入剖析深部煤层气地质特征与效益开发难点,总结大宁-吉县区块开发先导试验项目取得的进展和成效,明确开发规律并提出效益开发对策。结果表明:(1)深部煤层具有广覆式发育、含气性好、游离气含量高、保存条件好、煤体结构好、脆性指数高、顶底板封盖性强等地质特征,但微构造发育、渗透性极差、矿化度高等因素制约了深部煤层气效益开发;(2)不同地质条件下气井生产特征差异较大,通过先导试验落实气井产能和适应性开发技术对策,采用滚动开发模式可有效降低煤层强非均质性带来的开发风险;(3)开展地质-工程一体化井网优化设计,构建井网与缝网高度弥合的人造气藏,可实现资源动用和采收率最大化;(4)“长水平段+多段多簇+大砂量”的大规模、大排量极限体积压裂技术可增大有效改造体积和井控储量,大幅提高单井产量;(5)深部煤层气井具有“见气时间短、上产速度快、初期产量高、递减快”的生产特征,可实现短期快速规模上产,但气田长期稳产需持续新井投入;(6)前期开发成本偏高,实现效益开发需不断提高工程作业效率、降低开发成本。综合认为,深部煤层气资源品质好,可动用性强,具备快速推广复制条件,大宁-吉县区块深部煤层气开发实践可为国内其他区块深部煤层气规模动用提供技术借鉴,对加快深部煤层气规模勘探开发具有重要意义。

大宁–吉县区块深部煤层气多轮次转向压裂技术及应用

鄂尔多斯盆地东缘大宁-吉县区块深部煤层气资源丰度高,煤储层天然裂缝与煤自身割理裂隙发育、煤体结构好、机械强度高、顶底板封盖能力强,为大规模体积压裂缝网的形成提供了有利条件。超大规模压裂改造工艺使深部煤层气单井产量获得重大突破,但示踪剂监测结果显示,水平井各压裂段产气效果贡献不均一、资源动用存在盲区、综合效益未达预期。指出深部煤储层形成超大规模有效缝网面临两类主要挑战:(1)深部煤层裂缝扩展规律认识不清;(2)现有压裂技术存在过度改造及改造不充分区域。基于此问题,提出适合深部煤储层改造的多轮次转向缝网弥合压裂技术。首先,分析深部煤层超大规模缝网形成的可行性;其次结合现场压裂数据与微地震监测结果,分析地层曲率、倾角等对压裂裂缝扩展的影响;最后建立应力场计算方法,以此为依据,进行多轮次转向工艺优化及现场试验。在大宁-吉县区块现场进行试验验证,井周微应力场非均匀区域水力裂缝实现了较为均匀的扩展,增大了裂缝整体改造体积,单井产气效果较周边井有明显提升,其中DJ55井5轮次压裂,储层改造体积达到243.6×10^(4)m^(3),生产340 d累产气量970.5×10^(4)m^(3),平均日产气量2.85×10^(4)m^(3),日产量和压力均保持稳定,改造效果较好,预计采收储量(EUR)大于3000×10^(4)m^(3),产气潜力较大;JS8-6P05井第1-7段采用2~3轮次压裂,压后日产气量8.59×10^(4)m^(3),相比各段均采用单轮次压裂的JS8-6P04井加砂规模降低41.9%、压裂费用降低21%,但2口井水平段千米日产气量相当。试验效果表明,多轮次压裂工艺在一定程度上解决了水平井两侧应力差异而导致的裂缝单侧扩展问题,促进井筒两侧压裂裂缝趋于均匀扩展,极大程度上保障了深部煤储层资源动用程度和压后产量,是深部煤层气压裂工艺降本增效的主要技术途径。

鄂尔多斯盆地东缘深部煤层气高效开发理论技术体系

针对深部煤储层埋藏深、渗透率低、应力环境复杂等开发难题,总结大宁—吉县区块近5 a勘探开发取得成果,明确了资源富集条件、有效改造体积、水平段长、良好储盖组合条件是气井高产关键因素。在“人造气藏”开发理论指导下,建立了地质-工程一体化背景下的深部煤层气高效开发技术体系:(1)基于储层资源条件、构造保存条件和工程改造条件三大类11项指标,建立深部煤层气地质工程开发甜点评价标准;(2)基于微幅构造刻画、多尺度裂缝预测、三维地质模型构建等技术,形成“地质+工程”全要素定量化、可视化表征的煤储层精细评价技术;(3)按照“地质小尺度、三维地震微尺度、轨迹走靶体、少调快钻”导向思路,形成以钻前轨迹精优设计、精准入靶及靶后微调为核心的三阶段地质工程一体化导向技术;(4)按照实现资源动用和采收率最大化为目标,形成“地应力场、天然裂缝场、人工裂缝场、井型与方位、井网井距”五位一体井网优化设计技术;(5)依据深部煤层气赋存特征、渗流机理和气井生产特征,形成以产量不稳定分析法为主,经验产量递减法、数值模拟法和经验类比等多方法结合的气井产能评价及EUR预测技术;(6)遵循“四位一体”精准选段和“井间交错+段内差异化”设计原则,形成以构建人造气藏为目标的大规模体积压裂技术;(7)根据气井气水变化特征,形成全生命周期不同生产阶段排采优化控制技术;(8)结合当前AI技术进展与深部煤层气开发规律、集输等特征,探索了地质、工程、地面等多专业一体化协同环境下集输和数智化技术。在这一成果指导下,已投产29口水平井生产初期日产量5×10^(4)~16×10^(4) m^(3),平均10.2×10^(4) m^(3),区块日产气量突破300万m^(3),对加快鄂尔多斯盆地东缘深部煤层气规模上产具有重要指导意义,也为同类资源高效开发建立了参考标准。

鄂尔多斯盆地府谷地区深部煤层气富集成藏规律及有利区评价

鄂尔多斯盆地东缘神府区块是典型深部煤层气田,资源丰富且勘探开发潜力巨大。2023年10月,神府深部煤层大气田成功申报探明地质储量超1100亿m^(3)。府谷地区位于神府区块中部,是最早深部煤层气生产试验区,但目前对其煤层气的富集成藏规律和勘探开发潜力的认识尚不清楚。综合应用地震、测井、钻井和煤岩测试等资料以查明该地区深部煤层气地质特征、富集成藏规律和有利区分布。结果表明:主力煤层4+5、8+9号煤发育稳定且厚度较大(4+5号煤:3.2~5.8 m;8+9号煤:8.7~13.5 m),有利层段主要分布在煤层中上部位置;宏观煤岩类型主要为光亮-半亮煤,煤体结构主要为原生-碎裂结构煤;受深成变质作用的影响,煤类以气煤、肥煤和焦煤为主,煤的变质程度处于热解生气的高峰期,煤储层表现出中-高含气量(4+5号煤:3.0~12.0 m^(3)/t;8+9号煤:7.5~18.5 m^(3)/t)和中-高含气饱和度(35.0%~115.0%)等特征;主力煤层属于低渗储层((0.01~0.09)×10^(-3)μm^(2)),孔隙结构主要以微孔和小孔为主。提出府谷地区煤层气为“挠褶-断层-水动力”富集成藏模式,煤层气富集区位于构造平缓区和斜坡带。建立深部煤层气地质-工程双甜点评价体系,识别出I类地质-工程甜点区位于东部和西南部,是研究区深部煤层气勘探开发首选区带。因此,该研究认识进一步丰富了深部煤层气富集成藏理论,对鄂东缘深部煤层气勘探开发实践具有重要指导意义。

滨里海盆地东缘北特鲁瓦油田石炭系碳酸盐岩储层裂缝网络连通性评价

基于岩心、成像测井及裂缝网络建模结果,应用拓扑学理论,对滨里海盆地东缘北特鲁瓦油田石炭系碳酸盐岩储层裂缝网络的连通性进行了评价,并分析了其对油田开发的影响。研究结果表明:(1)滨里海盆地东缘北特鲁瓦油田石炭系碳酸盐岩储层裂缝切割类型可划分为高高切割、高低切割和低低切割,研究区A2,A3,G1,G2,G3及G4小层裂缝切割较为发育,且主要分布在构造高部位。(2)裂缝网络连通性可通过连通体面积占比、裂缝体密度、裂缝的平均长度和平均节点数4个参数进行定量评价,根据连通体面积大小、裂缝体密度大小及裂缝类型可对裂缝连通体进行定性分析和命名,研究区A2小层主要发育低低大连通体、高中大连通体和高高大连通体。(3)裂缝网络连通性和储层物性的耦合作用是油田水窜的原因,裂缝网络连通性主要与裂缝长度和裂缝体密度有关。

临兴区块深部煤层气井生产特征及影响因素

【目的】深部煤层气生产特征与中浅部煤层气生产特征具有明显区别,且同一区块内深部煤层气排采井也存在差异性。相关研究尚处于探索阶段,深入分析深部煤层气生产特征差异的影响因素对后续大规模开发阶段的产能预测与生产管理具有重要意义。【方法】为明确临兴区块深部煤层气生产特征及其影响因素,基于含气性、煤厚、埋深、水化学特征及压裂工艺等地质工程因素开展研究。【结果和结论】结果表明:(1)临兴区块深部煤层气井分为过饱和气藏自喷井、过饱和气藏排采井和欠饱和气藏排采井3类。(2)含气性是3种生产特征的主控因素,工区内1800~2000 m埋深的煤层气井含气量与稳产气量均相对较高。(3)欠饱和气藏排采井储层保存条件较差,水化学特征与其他两类井存在明显差异,导致其生产效果相对较差,且由于高矿化度和高碳酸氢根离子产生的管柱结垢与腐蚀导致排采不连续。(4)大规模压裂是提高气井产量的有效储层改造措施,压裂砂对裂缝的有效支撑是保障深部煤层气井高气量稳产的关键因素。上述成果明确了临兴区块深部煤层气生产特征差异影响因素,对研究区和邻近地区深部煤层气生产具有参考意义。

银川盆地东缘上地壳电性结构特征及地热勘探方向

随着银川盆地东缘地热井的成功实施,指明了围绕黄河断裂及其次级断裂寻找地热的新方向。为了进一步研究黄河断裂对银川盆地东缘地热资源的控制作用及缩小勘探靶区,共布设了4条MT测线,获得了71个测深点。通过对大地电磁测深资料进行预处理及二维反演,获得了研究区10 km以浅的二维电性结构。综合研究区以往地质、重力、微动、可控源音频大地电磁测深资料,对银川盆地东缘地层、断裂构造进一步解释,认为大地电磁测深测线所反映的奥陶系基底高阻内出现的相对低阻可能是黄河断裂后缘次级断裂发育部位,由奥陶系破碎充水所致,具有地热资源勘探的潜力。

柴达木盆地东缘德令哈柏树山大型天然饮用矿泉水成因分析

在对柴达木盆地东缘柏树山饮用矿泉群进行水文地质、控水断裂、水质等方面实地调查,对泉群的成因进行了研究。结果表明:矿泉群的水补给源为北部山区降水,补给源水通过大量的基岩裂隙补给深层地下水,径流至F2北倾活动性逆断层上盘时,形成富水“三角区”,并沿F2断层破碎带在上盘处排泄出地表,矿泉总流量达6446.3 m^(3)/d,是一处天然理想的矿泉水水源地。

含水致密气藏产能评价新方法——以鄂尔多斯盆地东缘致密气田为例

随着致密气勘探开发技术的发展,中海油临兴-神府区块致密气勘探取得突破,发现探明储量超千亿立方米的致密气田,然而相比于苏里格等气田,具有地层压力低、产水量大等特点。如何针对该类含水致密气藏产能进行评价对区块开发至关重要。基于该区块实际岩心开展启动压力梯度实验,创新定量评价启动压力梯度与渗透率和含水饱和度之间的关系。在此基础上利用气水两相流渗流力学理论,创新建立考虑动态启动压力梯度的含水致密气藏压裂气井多因素产能公式,并与现场实际试气结果进行对比,验证模型的准确性。研究分析地质工程因素对产能的影响。结果表明:含水饱和度对气井产能影响显著,随着储层含水饱和度的增加,气井产能大幅降低;随着启动压力梯度增加,气井产能降低并且气井存在最小流动压差,为气井生产策略提供依据;压裂工程改造中随着裂缝半长与渗透率的增加,气井产能增加,但是存在最优的裂缝渗透率值。研究成果可为优化致密气工程改造实施提供新的解决方案。