Reactive transport modeling constraints on the complex genesis of a lacustrine dolomite reservoir:A case from the Eocene Qaidam Basin,China

Reactive transport modeling(RTM)is an emerging method used to address geological issues in diagenesis research.However,the extrapolation of RTM results to practical reservoir prediction is not sufficiently understood.This paper presents a case study of the Eocene Qaidam Basin that combines RTM results with petrological and mineralogical evidence.The results show that the Eocene Xiaganchaigou Formation is characterized by mixed siliciclastic-carbonate-evaporite sedimentation in a semiclosed saline lacustrine environment.Periodic evaporation and salinization processes during the syngeneticpenecontemporaneous stage gave rise to the replacive genesis of dolomites and the cyclic enrichment of dolomite in the middle-upper parts of the meter-scale depositional sequences.The successive change in mineral paragenesis from terrigenous clastics to carbonates to evaporites was reconstructed using RTM simulations.Parametric uncertainty analyses further suggest that the evaporation intensity(brine salinity)and particle size of sediments(reactive surface area)were important rate-determining factors in the dolomitization,as shown by the relatively higher reaction rates under conditions of higher brine salinity and fine-grained sediments.Combining the simulation results with measured mineralogical and reservoir physical property data indicates that the preservation of original intergranular pores and the generation of porosity via replacive dolomitization were the major formation mechanisms of the distinctive lacustrine dolomite reservoirs(widespread submicron intercrystalline micropores)in the Eocene Qaidam Basin.The results confirm that RTM can be effectively used in geological studies,can provide a better general understanding of the dolomitizing fluid-rock interactions,and can shed light on the spatiotemporal evolution of mineralogy and porosity during dolomitization and the formation of lacustrine dolomite reservoirs.

Genetic mechanism and main controlling factors of high-quality clastic rock reservoirs in deep and ultradeep layers:A case study of Oligocene Linhe Formation in Linhe Depression,Hetao Basin,NW China

Based on new data from cores,drilling and logging,combined with extensive rock and mineral testing analysis,a systematic analysis is conducted on the characteristics,diagenesis types,genesis and controlling factors of deep to ultra-deep abnormally high porosity clastic rock reservoirs in the Oligocene Linhe Formation in the Hetao Basin.The reservoir space of the deep to ultra-deep clastic rock reservoirs in the Linhe Formation is mainly primary pores,and the coupling of three favorable diagenetic elements,namely the rock fabric with strong compaction resistance,weak thermal compaction diagenetic dynamic field,and diagenetic environment with weak fluid compaction-weak cementation,is conducive to the preservation of primary pores.The Linhe Formation clastic rocks have a superior preexisting material composition,with an average total content of 90%for quartz,feldspar,and rigid rock fragments,and strong resistance to compaction.The geothermal gradient in Linhe Depression in the range of(2.0–2.6)°C/100 m is low,and together with the burial history of long-term shallow burial and late rapid deep burial,it forms a weak thermal compaction diagenetic dynamic field environment.The diagenetic environment of the saline lake basin is characterized by weak fluid compaction.At the same time,the paleosalinity has zoning characteristics,and weak cementation in low salinity areas is conducive to the preservation of primary pores.The hydrodynamic conditions of sedimentation,salinity differentiation of ancient water in saline lake basins,and sand body thickness jointly control the distribution of high-quality reservoirs in the Linhe Formation.

Genesis Types and Diagenesis Compaction Mechanisms of Sandstone Rreservoirs in Dynamic Environments in Oil/Gas Basins in China

The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genesis types of thermal diagenesis, tectonic diagenesis and fluid diagenesis are presented on the basis of the dynamic environment of the oil/gas basins and.the controlling factors and mechanisms of sandstone diagenesis. Thermal diagenesis of sandstone reservoirs is related not only to the effect of formation temperature on diagenesis, but also to the significant changes in diagenesis caused by geothermal gradients. The concept of thermal compaction is presented. Thermal compaction becomes weaker with increasing depth and becomes stronger at a higher geothermal gradient. At the same formation temperature, the sandstone porosity in the region with a lower geothermal gradient is e^0.077＋0.0042T times higher than that in the region with a higher geothermal gradient. Both sudden and gradual changes are observed in diagenetic evolution caused by structural deformation. Average sandstone compaction increased by 0.1051% for every 1.0MPa increase of lateral tectonic compressional stress, while late tectonic napping helped to preserve a higher porosity of underlying sandstone reservoir. Fluid diagenesis is a general phenomenon. The compaction caused by fluid properties is significant. The coarser the grain size, the stronger the fluid effect on compaction. The greater the burial depth, the weaker the fluid effect on compaction for the specific reservoir lithology and the greater the difference in the fluid effects on compaction between different grain sizes.

A vertically integrated eutrophication model and its application to a river-style reservoir-Fuchunjiang,China

Based on a 2-D hydrodynamic model, a vertically integrated eutrophication model was developed. The physical sub-model can be used for calculation of water density at different depths, and the water quality sub-model was used for calculation of algal growth. The cohesive and non-cohesive sediments were simulated separately with different methods. The light extinction coefficient used in the underwater light regime sub-model was linearly related to the sum of sediment and phytoplankton biomass. Some components less important to the model were simplified to improve practicability and calculation efficiency. Using field data from Fuchunjiang Reservoir, we calculated the sensitivity of ecological parameters included in this model and validated the model. The results of sensitivity analysis showed that the parameters strongly influenced the phytoplankton biomass, including phytoplankton maximum growth rate, respiration rate, non-predatory mortality rate, settling rate, zooplankton maximum filtration rate, specific extinction coefficient for suspended solids and sediment oxygen demand rate. The model was calibrated by adjusting these parameters. Total chlorophyll α （chl-α） concentrations at different layers in the water column were reproduced very well by the model simulations. The simulated chl-α values were positively correlated to the measured values with Pearson correlation coefficient of 0.92. The mean difference between measured and simulated chl-α concentrations was 12% of the measured chl-α concentration. Measured and simulated DO concentrations were also positively correlated （r = 0.74） and the mean difference was 4% of measured DO concentrations. The successful validation of model indicated that it would be very useful in water quality management and algal bloom prediction in Fuchunjiang Reservoir and a good tool for water quality regulation of other fiver-style reservoirs.

Distribution Patterns of Remaining Hydrocarbons Controlled by Reservoir Architecture of Distributary Channel with Different Channel Style: S2 Formation of Songliao Basin, China

1 Introduction Reservoir architecture analysis of distributary channel of Daqing oilfield has drawn consistent interest among development geologists and petroleum engineers over the last decade(Lv et al.,1999;Zhou et al.,2008;Zhang et

Genesis and Development of Porosity in Carbonate Reservoirs─Fluid Inclusion Evidence

Fluid inclusions in minerals filled in pores of reservoir rocks can be used as a good indicator of pore genesis and development so as to shed light on oil generation, migration and accumulation. The relationship between pore evolution and oil generation has been established based on fluid inclusion studies on the Lower Ordovician carbonate reservoir strata in the Ordos Basin, Northwest China. Seven stages of porosity developrnent can be recognized, i. e., the penecontemporaneous, the early and middle-late diagenetic, the supergene, the early, middle and late re-burying stages. The dissolution pores and fissures formed in the supergene and middle-late reburying stages and the strtJctural fractures formed in the late re-burying stage constitute the major traps of oil and gas. The major phase of oil migration and accumulation took place between Late Jurassic and Cretaceous, corresponding to the middle and late re-burying stages. The generation and accumulation of oil can be closely-related to Yenshanian tectonics.

Dolomitization evolution and its effects on hydrocarbon reservoir formation from penecontemporaneous to deep burial environment

Aiming at the scientific problem that only part of dolomite acts as dolomite reservoir,this paper takes the multiple dolomite-bearing formations in the Tarim and Ordos basins,NW China and Sichuan Basin,SW China as the study object,by means of mineral petrological analysis and geochemical methods including carbonate clumped isotope,U-Pb isotopic dating,etc.,to rebuild the dolomitization pathway and evaluate its effects on reservoir formation.On the basis of detailed rock thin section observation,five dolomitic structural components are identified,including original fabric-retained dolomite(microbial and/or micrite structure),buried metasomatic dolomite I(subhedral-euhedral fine,medium and coarse crystalline structure),buried metasomatic dolomite II(allotriomorphic-subhedral fine,medium and coarse crystalline structure),buried precipitation dolomite and coarse crystalline saddle dolomite.Among them,the first three exist in the form of rocks,the latter two occur as dolomite minerals filling in pores and fractures.The corresponding petrological and geochemical identification templates for them are established.Based on the identification of the five dolomitic structural components,six dolomitization pathways for three types of reservoirs(preserved dolomite,reworked dolomite and limestone buried dolomitization)are distinguished.The initial porosity of the original rock before dolomitization and the dolomitization pathway are the main factors controlling the development of dolomite reservoirs.The preserved dolomite and reworked dolomite types have the most favorable dolomitization pathway for reservoir formation,and are large scale and controlled by sedimentary facies in development and distribution,making them the first choices for oil and gas exploration in deep carbonate formations.

Reservoir geological modeling and significance of Cambrian Xiaoerblak Formation in Keping outcrop area, Tarim Basin, NW China

Take the Cambrian Xiaoerblak Formation in the Keping(Kalpin) outcrop area as an example, a 28 km reservoir scale geological model was built based on description of 7 profiles, observation of more than 1000 thin sections, petrophysical analysis of 556 samples and many geochemical tests. The Xiaoerblak Formation, 158–178 m thick, is divided into three members and 5 submembers, and is composed of laminated microbialite dolomite(LMD), thrombolite dolomite(TD), foamy-stromatolite dolomite(FSD), oncolite dolomite(OD), grain dolomite(GD)/crystalline dolomite with grain ghost and micritic dolomite(MD)/argillaceous dolomite. The petrology features show that its sediment sequence is micro-organism layer – microbial mound/shoal – tidal flat in carbonate ramp background from bottom up. The reservoir has 5 types of pores, namely, framework pore, dissolved vug, intergranular and intragranular dissolved pore and intercrystalline dissolved pore, as main reservoir space. It is found that the development of pore has high lithofacies selectivity, FSD has the highest average porosity, TD, OD and GD come second. The reservoir is pore-vug reservoir with medium-high porosity and medium-low permeability. The dolomite of Xiaoerblak Formation was formed in para-syngenetic to early diagenetic stage through dolomitization caused by seawater. The reservoir development is jointly controlled by sedimentary facies, micro-organism type, high frequency sequence interface and early dolomitization. The classⅠand Ⅱ reservoirs, with an average thickness of 41.2 m and average reservoir-stratum ratio of about 25.6%, have significant potential. It is predicted that the microbial mounds and shoals in the middle ramp around the ancient uplift are the favorable zones for reservoir development.

Origin of carbonate minerals and impacts on reservoir quality of the Wufeng and Longmaxi Shale, Sichuan Basin

The Ordovician-Silurian Wufeng and Longmaxi Shale in the Sichuan Basin were studied to understand the genesis and diagenetic evolution of carbonate minerals and their effects on reservoir quality. The results of geochemical and petrological analyses show that calcite grains have a negative Ce anomaly indicating they formed in the oxidizing environment of seawater. The high carbonate mineral contents in the margin of basin indicate that calcite grains and cores of dolomite grains appear largely to be of detrital origin. The rhombic rims of dolomite grains and dolomite concretions with the δ^(13)C of –15.46‰ and the enrichment of middle rare earth elements were formed during the sulfate-driven anaerobic oxidation of methane. The calcite in radiolarian were related to the microbial sulfate reduction for the abundant anhedral pyrites and δ^(13)C value of –11.34‰. Calcite veins precipitated in the deep burial stage with homogenization temperature of the inclusions ranging from 146.70 ℃ to 182.90 ℃. The pores in shale are mainly organic matter pores with pore size mainly in the range of 1–20 nm in diameter. Carbonate minerals influence the development of pores through offering storage space for organic matter. When calcite contents ranging from 10% to 20%, calcite grains and cement as rigid framework can preserve primary pores. Subsequently, the thermal cracking of liquid petroleum in primary pores will form organic matter pores. The radiolarian were mostly partially filled with calcite, which combining with microcrystalline quartz preserved a high storage capacity.

The source and formation characteristics of the Zhujiadun gas reservoirs in the Yancheng Sag, Subei Basin

The Yancheng Sag is a favorable exploration area in the Subei Basin. However, the key geological understanding of the natural gas source and reservoir formation characteristics of the sag is still controversial. Based on a set of organic geochemical experiments conducted on natural gas and associated condensate oil of the first member of the Funing Formation (E1f1) in well YCh5 and well data analysis, the oil-gas resources and reservoir formation model in the Zhujiadun gas reservoir in the Yancheng Sag, Subei Basin, were investigated. The results of this study are as follows. (1) The natural gas in the Zhujiadun gas reservoir is dry gas with high methane content, low heavy hydrocarbon content, and high maturity. The characteristics of carbon and hydrogen isotopes in the natural gas indicate that the natural gas is oil-cracked gas, which mainly originates from the source rocks of the Permian Qixia Formation. (2) The condensate oil from well YCh5 with a high degree of maturity has a high pristane/phytane ratio, low gamma-paraffin abundance, and low tricyclic terpene abundance, indicating a mixture of the Upper Paleozoic condensate oil and Cenozoic crude oil. The saturated and aromatic hydrocarbons have similar δ13C values to the Cenozoic continental crude oil. These features suggest two sources of condensate oil. (3) Oils generated from the source rocks of the Qixia Formation were cracked into highly mature gas after deep burial, which migrated along large faults into the sandstones of the E1f1 and K1t1 members. This type of reservoir was effectively preserved beneath the overlying mudstone cap rocks. Therefore, it can be inferred that a play fairway might occur in the eastern zone of the faults connected to the Paleozoic source rocks in the Yancheng Sag since this zone has similar petroleum geological conditions to well YCh5. Therefore, this zone is a favorable area for further exploration.

川东北地区凉高山组致密砂岩孔隙特征及成因机制——以川东北铁山金窝剖面为例

文中以川东北铁山金窝剖面凉高山组为研究对象,综合野外露头样品,开展岩石铸体薄片、全岩X衍射、扫描电镜及孔隙度测试,系统分析了凉高山组砂岩的岩石学、储集空间、物性及成岩作用特征,探讨物性控制因素,明确储层成因机制。结果表明:研究区凉高山组砂岩成分及结构成熟度中—差,岩石类型以细粒长石岩屑砂岩为主;孔隙类型以残余原生粒间孔、粒内微孔、杂基/胶结物微孔为主,孔隙度介于0.64%~14.71%,平均为6.65%,物性较差;砂岩成岩特征表现为强压实、弱胶结、弱溶蚀。砂岩物性是物源、沉积条件及埋藏成岩过程共同作用的结果:小湖盆、近物源导致了砂岩搬运距离短,淘洗不充分,岩屑及塑性组分含量高;早期持续快速埋藏压实导致粒间孔隙快速损失、后期胶结和溶蚀受抑制。互层的烃源岩品质较差导致储层晚期溶蚀改造有限。喜山期抬升改造有利于改善储层物性。现今有利砂岩主要形成于水下分流河道。

Characteristics and genesis of shoal facies reservoir of the Lower Ordovician Tongzi Formation in southeastern Sichuan Basin,China

The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan Basin.However,the current studies mainly focus on the central part of the Basin,the systematic analysis of the southeastern part with well-developed shoal facies is lacking.This paper aims to clarify the characteristics and genesis of the Tongzi Formation reservoir in Southeastern Sichuan Basin,following an analysis of sedimentary facies within the sequence stratigraphic framework.The research shows that the main types of reservoir rocks are oolitic,intraclastic and bioclastic dolostones.And the reservoir spaces consist mainly of intergranular(dissolved)pores,intercrystalline(dissolved)pores,intragranular dissolved pores and fractures.Among them,intergranular pores account for the highest proportion,which is followed by intragranular dissolved pores.In addition,most throats are necking and flaky which mainly connect intergranular and intercrystalline pores,respectively.The diagenetic sequence shows that penecontemporaneous karst well improved the porosity of the reservoir in the early-stage although the cementation and compaction reduced parts of pores.The reservoir formation is associated with the tectonic-depositional settings,diageneses and terrigenous contamination.Paleohighlands and submerged uplifts,forming in the early Ordovician amalgamation between Yangtze and Cathaysia blocks,accumulated shoal sediments as the material basis for the reservoir formation.Penecontemporaneous karst forming intragranular dissolved pores and the dolomitization aiding grainstones to resist the pressure solution are the key to increasing porosity and preserving pores.The absence of terrigenous contamination prevented intergranular pores from being strongly cemented,which resulted in the reservoir difference between the central and southeastern Sichuan Basin.The study can be used as a reference for the further exploration of Ordovician petroleum in the Sichuan Basin and other regions owning similar geological settings.

柴北缘大柴旦地区地下热水成因:来自水化学及氢、氧、锶同位素的约束

为探究柴达木盆地北缘的大柴旦地热田的水化学特征及成因模式,本文对研究区14组地下热水进行了水化学组分和同位素(δD,δ^(18)O,^(87)Sr/^(86)Sr,3 H)分析。结果表明,大柴旦地下热水出露温度为52~74℃,溶解性总固体浓度(TDS)为959.8~1451.3 mg/L。地下热水的水化学类型为Cl-Na型,区内地下热水的水化学成分主要来源于蒸发岩和硅酸盐矿物的溶解;氢、氧稳定同位素特征表明,大气降水及冰雪融水是地下热水主要补给来源,且部分温泉有岩浆水的补给,估算的补给高程为3591~4374 m。3 H测年结果表明,区内地下热水主要由1952年之前的古水补给、蒸发作用和水-岩反应增强导致。XSWQ-06和XSWQ-07样品有明显的氧漂移。基于SiO_(2)地热温标、多矿物平衡法和硅焓模型估算出的地下热水的热储温度为171~227℃,循环深度为4.7~6.9 km。该地区地热资源具有较大的开发利用潜力。

济阳坳陷桩海地区碎屑岩优质储层特征及成因机制

济阳坳陷桩海地区油气资源丰富,新近系和潜山地层探明储量较高,而古近系钻探和认识程度较低,古近系储层特征和优质储层的成因机制认识不清。为此,通过岩心、薄片、扫描电镜等分析手段,对桩海地区东下段—沙河街组碎屑岩储层的岩石学特征、成岩作用类型、储集空间特征及优质储层控制因素进行了研究。结果表明:桩海地区东下段—沙河街组碎屑岩储层分布范围小、厚度薄,储层以近源快速沉积的砂岩为主,岩石成熟度较低;压实作用是破坏储层孔隙的主要原因,以碳酸盐岩为主的胶结作用对孔隙造成了进一步的破坏,而有机酸溶蚀是形成次生孔隙、造成储层增孔的重要因素;孔隙类型整体以次生孔隙为主,原生孔隙仅在西北物源区东下段储层保留程度相对较高,储层裂缝发育程度低;优质储层发育主要受控于沉积条件、成岩改造和断裂沟通3个条件。岩石成熟度高、远离钙源、靠近酸源、断裂沟通的砂砾岩储层为有利勘探目标。该研究可为桩海地区古近系勘探开发提供地质依据。

准噶尔盆地玛湖斜坡八道湾组低含油饱和度油藏地球化学特征分析

准噶尔盆地玛湖凹陷斜坡中浅层发现了侏罗系八道湾组低含油饱和度油藏,但是老井试油后产量不一,油藏“甜点”识别困难。为此,利用油气地球化学参数,对八道湾组油藏地球化学特征进行研究。结果表明:八道湾组低含油饱和度油藏原油的生物标志化合物特征对分析原油特点和原油成因具有显著的表征意义,原油普遍具有β-胡萝卜烷和γ-蜡烷丰度高的特征,为典型二叠系风城组烃源岩的产物。其中,低产井原油的γ-蜡烷丰度相对偏低,Ts/Tm较大;高产井原油的γ-蜡烷丰度较高,Ts/Tm偏小,色层效应是造成原油间生物标志化合物差异的主要原因。综合分析认为,断裂沟通方式及油藏充注过程影响了油气的聚集程度,晚期构造掀斜调整形成的八道湾组低含油饱和度油藏更具有勘探潜力。研究结果可为玛湖凹陷下一步勘探开发提供思路和方向。

蜀南自贡地区茅口组岩溶储层成因及地震预测方法

近年来,四川盆地下二叠统茅口组大量非构造圈闭钻井获得高产,证实了岩溶储层是茅口组岩性气藏的一个重要控制因素。但岩溶储层的成因及地震响应特征尚不明确,不同地区的岩溶储层预测方法不尽相同。通过对蜀南自贡地区茅口组构造特征、地层特征和岩溶储层地震响应特征研究,得出以下5方面认识:①台内滩相是岩溶储层发育的物质基础,自贡地区茅口组台内滩相主要在茅三段和茅二b段发育;②东吴运动差异抬升是研究区岩溶储层的主控因素;③断层形成于茅口组沉积之后,茅口组顶部岩溶储层受后期局部持续风化控制,茅口组内部岩溶储层受后期断层改造控制;④距茅口组顶距离不同,岩溶储层地震响应特征不同,茅三段表层型岩溶储层物性与茅口组顶部波峰振幅呈负相关,茅二b段内幕型岩溶储层物性则与茅口组内部波峰振幅呈正相关;⑤表层型岩溶储层在平面上不依赖断层且具有一定规模。

南羌塘古油藏白云岩成因机制及其油气地质意义

南羌塘隆鄂尼—昂达尔错—达卓玛古油藏白云岩是羌塘盆地最有利的碳酸盐岩储层之一,其成因机制对于羌塘盆地油气勘探突破具有十分重要的意义。在岩石薄片鉴定的基础上,结合碳氧稳定同位素、锶同位素、微量和稀土元素等测试分析,对古油藏白云岩成因机制及白云岩储层的形成演化开展研究。结果表明:(1)研究区共发育6种类型白云岩(石),分别为泥—粉晶残余结构白云岩、他形—半自形细晶白云岩、自形细晶白云岩、他形中—粗晶白云岩、雾心亮边晶粒白云岩和后期孔洞充填的马鞍形白云石。(2)古油藏白云岩存在多种成因。泥—粉晶残余结构白云岩成因为准同生期微生物白云石化作用,他形—半自形细晶白云岩和他形中—粗晶白云岩成因为浅埋藏阶段回流渗透白云石化作用,自形细晶白云岩成因为埋藏白云石化作用,雾心亮边晶粒白云岩是后期抬升至近地表混合水白云石化作用的产物。古油藏白云岩孔洞中大量充填的马鞍形白云石是热液白云石化作用的产物。(3)南羌塘古油藏白云岩储层受白云石化、大气淡水淋滤和热液溶蚀等成岩作用改造形成次生孔隙,形成了良好的规模储层,可作为油气勘探目的层之一。建立了南羌塘古油藏白云岩成因模式,为羌塘盆地油气成藏演化研究与优质碳酸盐岩储层预测提供了新的理论依据。

梁平地区二叠系长兴组台缘礁滩储层演化——来自天东110井岩石学及地球化学证据

天东110井是川东地区长兴组近年来获得的高产稳产井之一,该井的不同类型储层成因研究及模式建立对梁平地区长兴组勘探具有重要指示作用。基于天东110井长兴组丰富的取心资料,文中对其开展了岩石学、地球化学分析,建立了不同储集空间的演化模式,提出了高产井储层分布模式。结果表明:1)天东110井长兴组发育孤立状洞、溶洞、孔隙(包括针状孔及晶间孔)、高角度构造溶蚀缝。2)天东110井长兴组针状孔分布于礁滩体的颗粒云岩中,准同生期大气淡水溶蚀成孔、渗透回流白云岩化起关键保孔作用。3)缝洞形成受晚三叠世诺利期地层水溶蚀及瑞提期热液溶蚀作用控制,前者被沥青及巨晶方解石全充填,储集性能较差,后者部分被方解石、白云石、萤石等充填,充填程度低,孔渗性能好。下一步勘探应注重台地边缘的白云岩礁滩体微地貌高点与近晚三叠世瑞提期断裂及裂缝的热液溶蚀叠合发育区,可望获得更大突破。

太行山东南麓断裂带水文地球化学特征及水热成因模式

太行山东南麓断裂带发育,赋存丰富的中低温地热资源,然而,该地区深部地热水的水热成因模式依然不清楚。通过55组地热水和38组浅层地下水的水化学组分特征,研究离子组分来源及其运移规律,并借助同位素特征分析地热水补给来源,在此基础上分析深部热储的水岩平衡状态、热储温度和热循环深度。结果表明:研究区属对流—传导复合型地热系统,地热水整体处于氧化环境,离子组分以HCO_(3)^(-)和Na^(+)为主,主要受盐岩和碳酸盐岩等矿物的溶解及阳离子交替吸附作用控制;地热水的补给高程为1010~1153m,表明地热水补给区位于太行山东南麓西部的太行山地区;地热水循环深度范围为1125~4468 m;混合比例法估算汤阴断陷深层热储温度达到110~160℃,而汤阴断陷东部的内黄凸起地区为80~110℃,二者热储温度差别源自汤阴断陷两侧深切地幔的汤东、汤西深大断裂导热导水条件良好,以及内黄凸起的基岩埋深较浅,上伏盖层薄,热能更容易散失。本研究揭示了太行山东南麓地热系统的水文地球化学特征和水热成因模式,为该区地热资源开发利用提供重要依据。

Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.