Sedimentary Features and Their Implications of Microdigital Stromatolites from the Mesoproterozoic Wumishan Formation at the Jixian Section in North China

The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3000-m-thick stromatolitic carbonate succession.In this succession,several lithofacies units,that is,the subtidal stromatolitic biostrome,the thrombolitic bioherm,tidal-flat micritic dolomite and lagoon dolomitic shale,make up many meter-scale cycles of the peritidal carbonate type that have been nominated as the Wumishan cycles.Importantly,many microdigital stromatolites make up the stromatolitic biostrome unit of the Wumishan cycles in the lower part of the Wumishan Formation. These microdigital stromatolites have been grouped as a stromatolitic assemblage by paleontologists, that is,＂Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris＂assemblage.These microdigital stromatolites had also been interpreted as the aragonite（tufa） sea-floor precipitates by sedimentologists,and has further been thought as the special products of the transitional period from the sea-floor aragonite precipitates of the Archean to the clastic and muddy carbonates of the Neoproterozoic.Although there are some restrictions for the stratigraphic meaning of the concept of the stromatolitic assemblage,detailed studies on classification by paleontologists provide an important clue to understand the sedimentological meaning of the microdigital stromatolites.Furthermore,an important and obvious horizon for the end of the microdigital stromatolites was recorded in the Mesoproterozoic Wumishan Formation at the Jixian section,which provides useful information to understand the stromatolite decline occurred at c.1250 Ma and the evolving carbonate world of the Precambrian.

Molar-Tooth Structure from the Mesoproterozoic Wumishan Formation in Lingyuan,Yanshan Region,North China,and Geological Implications

Although its origin has not yet reached a consensus so far, MTS （Molar-Tooth Structure） has been documented for more than 100 years. Current study reports a discovery of MTS from the Mesoproterozoic Wumishan Formation, Lingyuan, Yanshan Region, North China, and the features and geological implications of MTS are further discussed. Here, straitigraphic horizons of MTS＇s occurrences show that it was mainly located within the top part of the Wumishan Formation, i.e., limestone unit. Four kinds of morphology of MTS, i.e., fine fusiform, debris, ribbon, ptigmatic and nodular （irregular）, were recognized and thought to be highly related to the sedimentary environments and facies. Geochemistry of MTS including oxides, trace elements and C, O and Sr isotopes indicates that the horizons of MTS-bearing is of higher Sr/Ba and Ca/Mg ratios, lower positive ~13C and highly negative 3180 values than the adjacent stratigraphic levels of rare MTS. Lithology, morphology and geochemistry of MTS in the Wumishan Formation suggest that MTS occurs mainly in shallow subtidal near the storm wave base, which is typically characterized by warm temperature, oversaturated calcium carbonate seawater and high organic productivity. Furthermore, occasional enrichment of algae bacteria here is more favorable for the calcification of calcium oozes and catalytic for MTS. C isotope composition of the Wumishan Formation and MTS of this study is well correlated with that of the Mesoproterozoic Belt Supergroup, North America and Riphean, Siberia, suggesting that MTS acts as a sedimentary record responding to global changes and is a perfect indicator in Precambrian stratigraphic correlation worldwide.

Deformed stromatolites in marbles of the Mesoproterozoic Wumishan Formation as evidence for synsedimentary seismic activity

The Mesoproterozoic Wumishan Formation consists mainly of dolomites that represent diagenetically transformed limestones deposited in a shallow peritidal environment.Although the environment was tectonically stable,the study area in the Changping District(north of the Beijing area) was affected by synsedimentary earthquakes.Later,the dolomites in the study area were intruded by a granite.This resulted in contact metamorphism of the dolomites,changing them in a halo around the intrusion into marble.This marble,which is exposed near Taoyukou Village,shows some levels with well-developed stromatolites.The stromatolites contain structures that point at deformation when the stromatolites had not yet been lithified,and thus represent soft-sediment deformation structures.The stromatolites apparently built up during a time-span when repeated deformational processes affected the still unlithified sediment,from the sedimentary surface down to maximally a few decimeters.The deformed stromatolites thus represent seismites,which feature is exceptionally rarely recognizable in marble.

Typical earthquake-induced soft-sediment deformation structures in the Mesoproterozoic Wumishan Formation, Yongding River Valley, Beijing, China and interpreted earthquake frequency

The Mesoproterozoic Wumishan Formation, composed of dolomite is a widely distributed stratigraphic unit in the Beijing area. It was formed over a long period of time in the Yan-Liao aulacogen, a stable peritidal environment that was ideal for recording earthquakes in the form of soft-sediment deformation structures (SSDS). Numerous examples occur in the upper part of the Wumishan Formation, along the Yongding River Valley. In addition, brittle structures include intrastratal fault and seismically cracked breccias. The soft-sediment deformation structures include liquefied features (diapirs, clastic dykes, convolute bedding), compressional deformation features (accordion folds, plate-spine breccias, mound-and-sag structures), and extensional plastic features (loop-bedding). Based on the regional geological setting and previous research, movements along the main axial fault of the Yan-Liao aulacogen are considered as the triggers for earthquakes since the Early Mesoproterozoic. The number and distribution of the SSDS suggest the major earthquake frequency in the Wumishan Formation of 20 to 32 thousand years.

Milankovitch-driven cycles in the Precambrian of China:The Wumishan Formation

Carbonate strata of the Mesoproterozoic Wumishan Formation in the Jixian area near Tianjin are ~3300 m thick and were deposited over some 100 million years(from ~1310±20 Ma to ~1207±10 Ma).Metre-scale cycles(parasequences) dominate the succession.They are generally of the peritidal carbonate type,and mostly show an approximately symmetrical lithofacies succession with thick stromatolite biostromes and small thromboliteoncolite bioherms constituting the central part and tidal-flat dolomites forming the upper and lower parts.Lagoonal-supratidal dolomitic shales with palaeosol caps make up the topmost layers.The boundaries of the Wumishan cycles are typically exposure surfaces,and there is abundant evidence for fresh-water diagenesis.Widespread 1:4 stacking patterns indicate that the individual Wumishan cycles are sixthorder parasequences,with 4 parasequences constituting one fifth-order parasequence set.Locally,5-8 beds or couplets,can be discerned in some of the cycles.The regular vertical stacking pattern of beds within the sixth-order parasequences,forming the fifth-order parasequence sets,are interpreted as the result of environmental fluctuations controlled by Milankovitch rhythms,namely the superimposition of precession,and short and long-eccentricity.The widespread 1:4 stacking pattern in the cyclic succession,as well as the local 1:5-8 stacking patterns of the beds within the cycles,suggest that the Milankovitch rhythms had similar ratios in the Mesoproterozoic as in the Phanerozoic.Based on the cycle stacking patterns,26 thirdorder sequences can be distinguished and these group into 6 second-order,transgressiveregressive megasequences(or sequence sets),all reflecting a composite,hierarchical succession of relative sea-level changes.

Earthquake-induced soft-sediment deformation structures in the Mesoproterozoic Wumishan Formation,North China,and their geologic implications

Soft-sediment structures are key to defining seismites. Two soft-sediment deformation horizons, bounded by undeformed carbonate strata, have been found in the Wumishan Formation in the Jumahe region, 175 km southwest of Beijing. One is in the lowest part of Wumishan Formation; and the other is in the uppermost part of Litho-member I. The soft-sediment structures in these two horizons fall into three categories: mould-and-sag structures, hydraulic shatterings and liquefaction dikes. The mould-and-sag structures are divided into two types: one developed in tidal-flat sediments, accompa-nied by many liquefaction-related structures and characterized by autochthonous post-earthquake sediments in sags, and the other type developed in deep-water environments, is not associated with liquefaction structures, and is overlain immediately by seismogenic tsunamites. The hydraulic shat-terings are composed of pockets of fluidization conglomerate, sand intrusions, and syndepositional faults. The liquefaction dikes fall into two categories: hydraulic-fracturing dikes and lateral-spreading dikes. The former are steep, planar, and pinch out upwards. The latter are snake-like and characterized by no diapir-related drag structures in surrounding rocks. Examination of the attitudes and strati-graphic positions of these structures suggests that these soft-sediment structures are seismogenic, and consequently, are seismites. Most seismites in the Wumishan Formation are developed near the former western, margin fault of Yanliao rift. This occurrence suggests that they could be related to movements on this fault. Other geological implications are discussed.

Origin of Molar-Tooth Structure Based on Sequence-Stratigraphic Position and Macroscopic Features: Example from Mesoproterozoic Gaoyuzhuang Formation at Jixian Section, Tianjin, North China

Both the macroscopic feature and the sequence-stratigraphic position of the molar-tooth structure developed in the third member of the Gaoyuzhuang （高于庄） Formation at the Jixian （蓟县） Section in Tianjin （天津） can provide some useful information about its origin and can reveal some problems to be further researched in the future. The Mesoproterozoic Gaoyuzhuang Formation is a set of 1 600 m thick carbonate strata. This formation can be divided into four members. The first member is mainly made up of stromatolitic dolomites; the second is marked by a set of manganese dolomites; the third is mainly composed of lamina limestones with the development of molar-tooth strcutures; the fourth is a set of stromatolitic-lithoherm dolomites. According to lithofacies and its succession, several types of meter-scale cycles can be discerned in the Gaoyuzhuang Formation： the L-M type, the subtidal type and the peritidal type. There is a regularly vertical stacking pattern for meter-scale cycles in the third-order sequence. Therefore, the Mesoproterozoic Gaoyuzhuang Formation can be divided into 13 third-order sequences （SQ1 to SQ13 ） and can further be grouped into 4 second-order sequences. The third member is marked by lamina limestones and can be grouped into three third-order sequences （SQ9 to SQ11 ）. The molar-tooth structure is developed in the middle part of the third sequence, i.e. SQH , in the third member. Several features of this kind of molar-tooth structure reflect some features of carbonate sedimentation in the Precambrian, such as the particular configuration, abundant organic matter, and easy silication. Stromatolites are chiefly formed in a shallow tidal-flat environment; lamina are mainly formed in the shallow ramp and molar-tooth structures are mainly generated in a relatively more deep-water environment from the middle to the deep ramp. Therefore, similar to stromatolite and lamina, the molartooth structure might also be a kind of bio-sedimentation structure. This suggestion is based on macroscopic observation and the sedimentary-facies analysis of the molar-tooth structures from the sequencestratigraphic position. These features of Precambrian sedimentation also reveal the problem of Precambrian carbonate sedimentation. With more detailed study, a more practical solution for these problems may be obtained in the future.

天津滨海地热田北部深部地热资源赋存规律

【研究目的】天津地热资源丰富,目前已开发的深部地热资源大部分位于“隆中凸”构造区域,而位于“坳中凸”构造区域的地热资源勘查和研究程度基本尚属空白,揭示其深部地热赋存规律可为滨海新区及京津冀地区寻找深部地热资源及勘探与开发提供重要参考。【研究方法】本文以黄骅坳陷宁河凸起中的桥沽地区为研究区,以近期新发现的资源禀赋最好的蓟县系雾迷山组热储层为研究对象,通过分析区域地质资料、大地电磁测深(MT)、钻孔测温和物探测井等资料,系统总结了研究区地质构造、地温场和深部地热资源赋存特征。【研究结果】雾迷山组储层的热储温度高(90~120℃),出水量大于100 m^(3)/h,埋藏相对较浅(2200~2800 m)。区内地质构造条件复杂,断裂构造发育,汉沽断裂为研究区重要的导热、导水通道;地温场呈现“两高夹一低”展布特征与两处背斜构造空间位置相对应;热源以壳源热为主、幔源热次之,大气降水为主要热水来源,热传输机制以热传导型为主。【结论】综合研究区深部地热赋存规律,建立了深部地热资源概念模型,明确了“坳中凸”深部地热找矿新思路。

容城地热田雾迷山组碳酸盐岩热储层裂缝主控因素及成因机制

容城地热田雾迷山组是华北地区典型的低孔隙度碳酸盐岩热储层,也是地热流体勘探的主要目标。裂缝对研究区地热流体的富集和产能有重要影响。本文通过对研究区岩心、薄片和成像测井等资料的分析,确定了裂缝的发育特征、控制因素和形成期次。结果表明容城地热田雾迷山组碳酸盐岩热储层裂缝多为未充填的高角度斜交缝,11.8%的裂缝被方解石和石英脉充填。裂缝开度主要集中在0~2 mm,靠近断裂的D19井开度最大(均值为3.65 mm),孔隙度也最大(均值为0.7523%),裂缝孔隙度随开度的增大线性增加。裂缝在断裂附近或者构造应力场较大的区域更为发育,受构造作用影响最明显。在同一构造环境和应力场下,岩性是控制研究区裂缝发育的主导因素。容城地热田雾迷山组碳酸盐岩热储层裂缝大致分为3组,印支期形成的NNE-SSW与NW-SE向“X”型共轭剪裂缝,燕山晚期形成的NEE-SWW向剪裂缝,以及喜马拉雅期形成的近E-W向张裂缝。

雄安新区三维地热地质模型方法研究

根据区域地质资料、钻井地层数据、测井资料,分别对雄安新区构造进行网格化并建立构造模型,应用层序地层学原理厘定等时界面及地层框架,选取建模参数,建立沉积相三维模型.采用相控条件下的序贯高斯模拟算法,建立孔隙度、渗透率模型.根据实测,得出区域内盖层、储层、基岩的岩石热导率,并建立雾迷山组温度场模型.最后采用物性参数展布对比、概率模型一致性、拟合三方面对地质模型进行验证,结果表明,此地质模型的孔隙度、渗透率概率分布特征与测井解释曲线数据和初始化数据基本一致,说明该模型与地质认识吻合度超过90%,所建地质模型合理.

Basic Lithofacies-Succession Model for the Wumishan Cyclothems: Their Markov Chain Analysis and Regularly Vertical Stacking Patterns in the Third-Order Sequences

The Mesoproterozoic Wumishan Formation in the Jixian section of Tianjin is a succession of 3300-m-thick carbonate strata formed in a period of about 100 Ma (1310±20 Ma-1207±10 Ma). In this succession of strata, the carbonate metre-scale cyclic sequences belonging to peritidal type with an approximately symmetrical lithofacies-succession are best developed. The wide development of 1:4 stacking patterns shows that these metre-scale cyclic sequences are genetically related to the short-eccentricity cycles, which are called the Wumishan cyclothems that could truly represent sedimentary cycles. Generally, massive and thick-bedded calcareous dolomites and dolomitic limestones of stromatolite biostromes and thrombolite bioherms constitute the central part of the Wumishan cyclothems. The lower and upper parts consist of tidal flat dolostones, sandy-muddy dolostone and the top part is composed of lagoonal facies dolomitic shales with a paleosol cap. Therefore, an approximately symmetrical lithofacies-succession is formed. Many features such as the clear deepening and shoaling vectors of cyclothems, and all kinds of marks of fresh-water diagenesis indicate that the Wumishan cyclothems are the product of autocyclic sedimentation governed by allocyclic high-frequency sea-level changes. The results of a Markov chain analysis reaffirm the existence of the lithofacies-succession model of the Wumishan cyclothems. The boundaries of the Wumishan cyclothems are marked by the instantaneous exposed punctuated surface, which leads to the discrepancy between the cyclothems and the parasequences of the sequence stratigraphy terminology system. It is difficult to form a judgment that the time span of the Milankovitch cycles in the Precambrian is certainly equal to that of the Phanerozoic, but the regularly vertical stacking patterns of the seventh-order rhythms, sixth-order cyclothems and fifth-order parasequence sets still indicate their consistency with the duration of the Milankovitch cycles in the Phanerozoic.

雄安新区雾迷山组岩溶热储成储机制及发育模式

雄安新区雾迷山组地热资源丰富,研究其岩溶热储特征及其形成机理对于雄安新区清洁地热资源的开发利用具有重要的理论意义和实用价值。前人已经对该区雾迷山组油气储集层的分布、古岩溶、成岩作用、储集空间等特征做过一定的研究,但对于该区雾迷山组地热资源的成储机制、特别是3期岩溶等成岩特征尚缺乏系统性的研究。充分利用野外露头、岩心、薄片和测录井等地质及地球物理资料,并结合区域地质背景的分析,对雄安新区雾迷山组的岩石学特征、成岩作用、岩溶热储的成储机制进行了深入研究,并建立了雄安新区雾迷山组岩溶热储的发育模式。结果表明:(1)雄安新区雾迷山组主要岩性为白云岩,主要的储集空间为次生孔隙和构造缝—构造溶蚀缝,热储孔渗变化较大;(2)雄安新区最主要的建设性成岩作用是3种溶蚀作用,包括同生—准同生溶蚀、表生溶蚀和埋藏溶蚀,主要破坏性成岩作用是压实作用和胶结作用;(3)根据构造演化、岩心及测井资料,将表生溶蚀作用划分为3期,分别是芹峪期、印支期和燕山—喜山期。芹峪期雾迷山组局部出露遭受淋滤,形成的溶孔经后期改造后不易识别;印支期大部分区域抬升并遭受淋滤,形成高孔渗储集层,后期遭受了进一步改造;燕山—喜山期是雄安新区规模最大、影响最广泛的表生岩溶作用形成期,对前期的储集层进一步淋滤、改造,形成大范围的优质储集层。最后提出了雄安新区雾迷山组优质岩溶热储的成储机制与模式,指出了岩溶热储的有利发育区。

雄安新区地层及主要热储空间结构特征与地热水资源潜力

雄安新区中深层白云岩热储地热资源丰富,为了提高对该区主要热储白云岩热储特征及地热水资源潜力的认识程度,指导新区中深层白云岩热储地热水资源的规模化开发,基于钻井、地震、地质等资料,研究了该区白云岩热储的地层空间分布、构造特征、储集空间特征和主建设区白云岩热储地热水资源潜力。研究表明:雄安新区主要热储雾迷山组、高于庄组除在断裂面部分地区外基本全区分布;雾迷山组埋深在容城凸起、牛驼镇凸起相对较浅,在高阳低凸起相对较深;高于庄组有类似的分布特征,总体埋深更深,温度更高;其它地层除第四系、新近系明化镇组外分布都比较局限;区内发育众多以NNE向为主的正断层,与少数其它方向断裂交会,将深部地热通过流体传输到浅部,并造就断裂两侧大量的裂缝和控制岩溶发育方向及规模,形成众多溶蚀孔洞;同时构造演化中雾迷山组古地貌中高地貌部分,在喜山期大多剥蚀与新生界形成不整合面,共同构成本区重要的输导通道和储集空间,岩溶孔洞和裂缝结合型复合空间是本区雾迷山组主要热储空间,单独的裂缝、孔洞是次要热储空间,大型溶洞一旦发育往往是主力产水层;新区主建设区顶面在5000 m(底部埋深可达6000 m)及以浅的白云岩岩溶裂缝热储地热水资源,按100年采用总热水储量的50%及500 m井距“三采两灌”原则单井产量110 m^(3)/h计,最适宜生产井布井数目233口,主建设区现阶段可满足每年4787×10^(4)m^(2)的供暖面积,占实际需求的30.1%。结论认为:雾迷山组埋深较浅,在当前经济技术条件下是主力热储,高于庄组埋深较深是最重要的备用热储,今后20年内会被大规模开发利用,但即便现在同时开发它们也不能满足雄安新区主建设区的清洁能源需求,需要发展“多能互补”系统,域外的过剩地热资源能否向域内目标区集输受经济成本和环境成本风险制约。在当下和未来发展与应用节能保温技术既重要也必要。

天津山岭子地热田蓟县系雾迷山组热储流体同位素特征及其指示意义

为分析天津山岭子地热田地热流体化学成因、赋存条件及物质来源,笔者通过采集地热流体样品和测试分析,对天津山岭子地热田蓟县系雾迷山组地热流体同位素特征进行了研究,总结了天津山岭子地热田蓟县系雾迷山组地热流体起源与形成机理。结果表明:研究区蓟县系雾迷山组地热流体^(87)Sr/^(86)Sr范围为0.7113~0.7118,指示碳酸盐岩溶解成因,表现出明显的时间累积效应;蓟县系雾迷山组热储流体的^(40)Ar/^(36)Ar范围为301~412,远小于幔源^(40)Ar/^(36)Ar,可排除其幔源物质成因。δ^(34)S范围为34.1‰~34.6‰,气体组分含量以氮气和甲烷为主,指示其还原环境。本文研究结果对山岭子地热田地热资源的开发利用具有借鉴参考意义。

天津东丽湖深部岩溶热储时频电磁法探测及有利区预测

天津市地热资源储量丰富,蓟县系雾迷山组作为主力热储,是典型的碳酸盐岩型热储层。为查明天津东丽湖5 km以浅的地层结构和隐伏断裂、重点查明深部主力热储层空间分布及结构特征、预测地热有利区,笔者首次将主要用于深部油气勘探的时频电磁法应用于东丽湖深部地热资源探测。通过高标准的数据采集、精细化数据处理和电阻率约束反演,结合地震和钻孔资料进行层位标定,精细刻画了地层结构:推断了7条隐伏断裂,均为NNE与NWW向的拉张性正断层,其中沧东断裂F1作为区内主要热流体的必要通道,导热、储热并控制着地热异常区的分布和形态;雾迷山组热储层主要分布在沧东断裂西侧,顶界面埋深海拔约-2200~-2400 m,在电阻率剖面上显示为连续递增的A型电性特征,三、四段岩溶裂隙较发育时,热水在裂隙或断裂处的聚集引起局部低电阻率异常,出现H型电性特征,指示了目标深度内地热有利区的发育部位。据此,本文圈定地热有利区4处,为后续地热资源的开发利用提供了重要的基础资料和支撑。

基于可钻性分析及三维地质建模的钻探有利区优选:以雄安新区雾迷山组为例

针对雄安新区深部雾迷山组白云岩地热储层非均质性强和可钻性差等特点,本文基于丰富的钻井、岩心、薄片和测井解释等数据,建立雄安新区各层系岩性测井解释模型,将雾迷山组岩石类型划分为结晶白云岩、颗粒白云岩、微生物白云岩、硅质白云岩和角砾白云岩5类。结合抗压强度、硬度和研磨性等可钻性参数测定结果,将雾迷山组角砾白云岩和柱状叠层石白云岩的可钻性级别归为易钻级,颗粒白云岩和层纹石的可钻性级别归为中钻级,块状泥晶白云岩和硅质白云岩的可钻性级别划为难钻级。利用地质建模技术,建立雄安新区三维地质模型,从而明确研究区各地层展布、岩性分布和可钻性变化的规律。最终圈定牛驼镇凸起和容城凸起为钻进效率最高、钻井成本最低的钻探靶区,高阳低凸起、同口—雁翎低潜山带、任丘低潜山带、牛北斜坡和蠡县斜坡区域为次有利的潜力钻探靶区,而凹陷区地层钻进难度较大且成本较高,为高风险的钻探靶区。该结果可为雄安新区深部岩溶热储的钻井地质设计、工艺优化和效率提高提供参考。

雄安新区蓟县系雾迷山组地层水对白云岩溶蚀的模拟实验研究

为了研究雄安新区雾迷山组地层水对白云岩的溶蚀作用,文章以雾迷山组白云岩为研究对象,以井下雾迷山组地层水为实验流体,开展高温高压条件下溶蚀模拟实验。实验结果表明:(1)样品在地层水中的溶蚀速率随温度增加总体呈下降趋势,具有快速下降—缓慢增加—快速下降的特征,在100~140℃范围内明显增加。样品在地层水中的溶蚀速率随压力增加明显增大。反应溶液的Ca^(2+)、Mg^(2+)浓度增加量随温度、压力变化特征与样品溶蚀速率随温度、压力变化特征一致;(2)孔隙、微裂隙欠发育的样品仅在样品表面发生溶蚀,使得样品表面变模糊。孔隙、微裂隙发育的样品,沿粒间、晶间孔隙及各类裂隙溶蚀、扩展,最终呈一定程度连通;(3)埋藏成岩环境下,在100~140℃范围存在一个保持较高溶蚀能力的温度窗口,这可能是研究区雾迷山组白云岩岩溶储层形成的有利温度区间。

天津市南部平原区雾迷山组热储岩溶裂隙发育规律

蓟县系雾迷山组是天津主力开发的热储层位,对这套地层的研究主要集中在热储层温度场、动力场、水化学场和地表水回灌等方面,在热储岩溶裂隙方面的研究较少。通过对天津市138眼雾迷山组地热井的完井和测井资料进行对比分析,统计了不同构造单元雾迷山组一、二类裂缝发育,热储顶板埋深,地热井单位涌水量和上覆不同地层的情况,总结了其岩溶裂隙发育规律。结果表明:雾迷山组岩溶裂隙较发育,漏失部位距热储顶板埋深距离集中在100 m以浅;热储顶部岩溶发育,裂隙发育受上覆不同地层的影响不大,裂隙发育与该层顶板埋深的相关性不明显,但整体上有裂隙发育随顶板埋深加大而略有减小的趋势;地热井的单位涌水量随裂隙发育程度的增大而变大;热储裂隙比集中在0.1~0.4,受构造影响,在张性断裂构造带、断裂交汇和背斜轴部热储构造裂隙较发育。研究结果可为天津市雾迷山组地热的有效开发利用与地热钻探提供参考。

冀中坳陷任丘潜山雾迷山组微生物白云岩储层特征及演化

综合利用野外露头、钻井岩心、岩石薄片、测录井及分析化验等资料,对冀中坳陷任丘潜山雾迷山组微生物白云岩储层特征及类型开展研究,总结分析优质储层形成控制因素及演化规律。结果表明:雾迷山组主要发育微生物白云岩和与微生物相关的颗粒白云岩,其中微生物白云岩包括叠层石、凝块石、层纹石和核形石白云岩,与微生物相关的颗粒白云岩主要为砂砾屑白云岩;储集空间分为孔隙、裂缝、溶洞3大类,储层整体物性较差,整体上属于孔洞缝复合型低孔低渗储层,可进一步划分为Ⅰ、Ⅱ、Ⅲ类储层。沉积环境是储层形成与演化的基础,溶蚀作用是形成多类型储集空间的关键,构造破裂作用是形成有效储集空间的重要补充。雾迷山组微生物白云岩储层演化经历沉积-同生成孔、Ⅰ期表生增孔、浅埋藏减孔、褶皱断裂改造-Ⅱ期表生增孔、深埋藏减孔等5个阶段,多因素共同作用最终形成现今2%~5%的孔隙度。

温敏型形状记忆聚合物及其在雄安新区热储钻进的应用展望

雄安新区地热资源丰富,其深部蓟县系雾迷山组碳酸盐岩热储是目前首要的目标储层。其碳酸盐岩热储高度发育地裂隙网使得钻井中存在钻井液严重漏失与储层伤害问题,导致地热井产能下降。为在实现地热钻井裂隙封堵的同时不伤害热储层,从而最大程度地提高地热井产能,本文提出应用温敏型形状记忆聚合物对温度响应的形状记忆特性以实现雄安新区裂隙型碳酸盐岩热储钻进过程中屏蔽暂堵。温敏型形状记忆聚合物既能够有效地应对雄安新区目标热储由于裂隙发育而造成的钻井液漏失问题,在地热井生产时又能够完全离开储层裂隙从而最大程度实现热储保护,是一种具有发展潜力的裂隙型热储屏蔽暂堵技术,为雄安新区高效地热钻井及热储保护技术提供一种新的技术手段。