Geologic characteristics,exploration and production progress of shale oil and gas in the United States:An overview

We present a systematic summary of the geological characteristics,exploration and development history and current state of shale oil and gas in the United States.The hydrocarbon-rich shales in the major shale basins of the United States are mainly developed in six geological periods:Middle Ordovician,Middle-Late Devonian,Early Carboniferous(Middle-Late Mississippi),Early Permian,Late Jurassic,and Late Cretaceous(Cenomanian-Turonian).Depositional environments for these shales include intra-cratonic basins,foreland basins,and passive continental margins.Paleozoic hydrocarbon-rich shales are mainly developed in six basins,including the Appalachian Basin(Utica and Marcellus shales),Anadarko Basin(Woodford Shale),Williston Basin(Bakken Shale),Arkoma Basin(Fayetteville Shale),Fort Worth Basin(Barnett Shale),and the Wolfcamp and Leonardian Spraberry/Bone Springs shale plays of the Permian Basin.The Mesozoic hydrocarbon-rich shales are mainly developed on the margins of the Gulf of Mexico Basin(Haynesville and Eagle Ford)or in various Rocky Mountain basins(Niobrara Formation,mainly in the Denver and Powder River basins).The detailed analysis of shale plays reveals that the shales are different in facies and mineral components,and"shale reservoirs"are often not shale at all.The United States is abundant in shale oil and gas,with the in-place resources exceeding 0.246×10^(12)t and 290×10^(12)m^(3),respectively.Before the emergence of horizontal well hydraulic fracturing technology to kick off the"shale revolution",the United States had experienced two decades of exploration and production practices,as well as theory and technology development.In 2007-2023,shale oil and gas production in the United States increased from approximately 11.2×10^(4)tons of oil equivalent per day(toe/d)to over 300.0×10^(4)toe/d.In 2017,the shale oil and gas production exceeded the conventional oil and gas production in the country.In 2023,the contribution from shale plays to the total U.S.oil and gas production remained above 60%.The development of shale oil and gas has largely been driven by improvements in drilling and completion technologies,with much of the recent effort focused on“cube development”or“co-development”.Other efforts to improve productivity and efficiency include refracturing,enhanced oil recovery,and drilling of“U-shaped”wells.Given the significant resources base and continued technological improvements,shale oil and gas production will continue to contribute significant volumes to total U.S.hydrocarbon production.

Growth behavior and resource potential evaluation of gas hydrate in core fractures in Qilian Mountain permafrost area, Qinghai-Tibet Plateau

The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.

A Review on Shale Reservoirs as an Unconventional Play--The History,Technology Revolution,Importance to Oil and Gas Industry,and the Development Future

As a milestone of the entire energy industry,unconventional resources have inevitably swept the world in the last decade,and will certainly dominate the global oil and gas industry in the near future.Eventually,the ＂unconventional＂ will become ＂conventional＂.Along with the rapid development,however,some issues have emerged,which are closely related to the viability of unconventional resources development.Under the current circumstances of low crude oil and gas price,coupled with the prominent environmental concerns,the arguments about the development and production of unconventional resources have been recently heated up.This work introduced the fullblown aspects of unconventional resources especially shale reservoirs,by discussing their concepts and definitions,reviewing the shale gas and shale oil development history and necessity,analyzing the shale plays＇ geology and petroleum systems with respects to key hydrocarbon accumulation elements and mechanisms,and summarizing the technology resolution.This study also discussed the relevant key issues,including significant estimation uncertainty of technically recoverable resources,the equivocal understanding of complex geology preventing the production and technologies implementation optimization,the difficulties of experiences and technologies global expanding,and the corresponding risks and uncertainties.In addition,based on the latest production and exploration data,the future perspective of the unconventional resources was depicted from global unconventional resources assessments,technology development,and limitations constraining the development.

A"One Engine with Six Gears"System Engineering Methodology for the Economic Development of Unconventional Oil and Gas in China

Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive amount of resources and the rapid growth of proven geological reserves.The challenges of technology,cost,management,and methodology restrict large-scale and economic development.Based on successful practices,a"one engine with six gears"system engineering methodology is put forward,which includes life-cycle management,overall synergy,interdisciplinary cross-service integration,marketoriented operation,socialized support,digitalized management,and low-carbon and green development.The methodology has been proved to be effective in multiple unconventional oil and gas national demonstration areas,including the Jimusar continental shale oil demonstration area.Disruptive views are introduced-namely,that unconventional oil and gas do not necessarily yield a low return,nor do they necessarily have a low recovery factor.A determination to achieve economic benefit must be a pervasive underlying goal for managers and experts.Return and recovery factors,as primary focuses,must be adhered to during China’s development of unconventional oil and gas.The required methodology transformation includes a revolution in management systems to significantly decrease cost and increase production,resulting in technological innovation.

Distribution and potential of global oil and gas resources

Using conventional and unconventional oil and gas resource evaluation methods with play as a unit, this study evaluates the oil and gas geology and resource potential of conventional oil and gas resources and seven types of unconventional resources in the global major oil and gas basins(excluding China). For the first time, resource evaluation data with independent intellectual property rights has been obtained. According to evaluation and calculation, the global recoverable conventional oil resources are 5 350.0×108 t, the recoverable condensate oil resources are 496.2×108 t, and the recoverable natural gas resources are 588.4×1012 m3. The remaining oil and gas 2 P recoverable reserves are 4 212.6×108 t, the reserve growth of oil and gas fields are 1 531.7×108 t. The undiscovered oil and gas recoverable resources are 3 065.5×108 t. The global unconventional oil recoverable resources are 4 209.4×108 t and the unconventional natural gas recoverable resources are 195.4×1012 m3. The evaluation results show that the global conventional and unconventional oil and gas resources are still abundant.

Geological characteristics and ‘‘sweet area'' evaluation for tight oil

Tight oil has become the focus in exploration and development of unconventional oil in the world, especially in North America and China. In North America, there has been intensive exploration for tight oil in marine. In China, commercial exploration for tight oil in conti- nental sediments is now steadily underway. With the dis- covery of China＇s first tight oil field--Xin＇anbian Oilfield in the Ordos Basin, tight oil has been integrated officially into the category for reserves evaluation. Geologically, tight oil is characterized by distribution in depressions and slopes of basins, extensive, mature, and high-quality source rocks, large-scale reservoir space with micro- and nanopore throat systems, source rocks and reservoirs in close contact and with continuous distribution, and local ＂sweet area.＂ The evaluation of the distribution of tight oil ＂sweet area＂ should focus on relationships between ＂six features.＂ These are source properties, lithology, physical properties, brittleness, hydrocarbon potential, and stress anisotropy. In North America, tight oil prospects are distributed in lamellar shale or marl, where natural fractures are fre- quently present, with TOC 〉 4 %, porosity 〉 7 %, brittle mineral content 〉 50 %, oil saturation of 50 %-80 %, API 〉 35~, and pressure coefficient 〉 1.30. In China, tight oil prospects are distributed in lamellar shale, tight sand- stone, or tight carbonate rocks, with TOC 〉 2 %, poros- ity 〉 8 %, brittle mineral content 〉 40 %, oil saturation of 60 %-90 %, low crude oil viscosity, or high formation pressure. Continental tight oil is pervasive in China and its preliminary estimated technically recoverable resources are about （20-25） × lO8^ t.

Research progress and challenges of natural gas hydrate resource evaluation in the South China Sea

As an efficient clean energy,natural gas hydrate(NGH)has become a hot topic in recent researches.Since1990 s,China has made great achievements and progress in NGH exploration in the South China Sea(SCS),including determination of the favorable distribution areas and favorable strata thickness,identification of the dual source for accumulation,evaluation of the prospective gas contents,verification of the widespread existence,and confirmation of the technical recoverability of NGH resources.However,there are three major challenges in the NGH studies.First,all the 24 national key and major projects in the SCS focused on trial production engineering and geological engineering in the past 20 years,while 8 of the 10 international NGH research projects focused on resource potential.Second,resource evaluation methods are outdated and some parameter selection are subjective.Third,the existing resource evaluation results are low-level with a great uncertainty,and cannot be used to guide NGH exploration and production or strategic research.To improve the evaluation of NGH resources in the SCS,future researches should focus on four aspects:(1)improve the research on the criterion of the objective existence of NGH and the method of prediction and evaluation;(2)apply new theories and methods from the global NGH research;(3)boost the research on the difference and correlation of the conditions of hydrocarbon migration and accumulation in different basins;(4)innovate the theory and method of NGH resource potential evaluation.

Analysis of the world oil and gas exploration situation in 2021

The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries;second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly;third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins;fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.

Buoyance-driven hydrocarbon accumulation depth and its implication for unconventional resource prediction

The discovery of unconventional hydrocarbon resources since the late 20th century changed geologists’understanding of hydrocarbon migration and accumulations and provides a solution to energy shortage.In 2016,unconventional oil production in the USA accounted for 41%of the total oil production;and unconventional natural gas production in China accounted for 35%of total gas production,showing strong growth momentum of unconventional hydrocarbons explorations.Unconventional hydrocarbons generally coexist with conventional petroleum resources;they sometimes distribute in a separate system,not coexisting with a conventional system.Identification and prediction of unconventional resources and their potentials are prominent challenges for geologists.This study analyzed the results of 12,237 drilling wells in six representative petroliferous basins in China and studied the correlations and differences between conventional and unconventional hydrocarbons by comparing their geological features.Migration and accumulation of conventional hydrocarbon are caused dominantly by buoyance.Wepropose a concept of buoyance-driven hydrocarbon accumulation depth to describe the deepest hydrocarbon accumulation depth driven dominantly by buoyance;beyond this depth the buoyance becomes unimportant for hydrocarbon accumulation.We found that the buoyance-driven hydrocarbon accumulation depth in petroliferous basins controls the different oil/gas reservoirs distribution and resource potentials.Hydrocarbon migration and accumulations above this depth is dominated by buoyancy,forming conventional reservoirs in traps with high porosity and permeability,while hydrocarbon migration and accumulation below this depth is dominated by non-buoyancy forces(mainly refers to capillary force,hydrocarbon volumeexpansion force,etc.),forming unconventional reservoirs in tight layers.The buoyance-driven hydrocarbon accumulation depths in six basins in China range from 1200mto 4200 m,which become shallowerwith increasing geothermal gradient,decreasing particle size of sandstone reservoir layers,or an uplift in the whole petroliferous basin.The predicted unconventional resource potential belowthe buoyance-driven hydrocarbon accumulation depth in six basins in China is more than 15.71×10^(9) t oil equivalent,among them 4.71×10^(9) t reserves have been proved.Worldwide,94%of 52,926 oil and gas reservoirs in 1186 basins are conventional reservoirs and only 6%of them are unconventional reservoirs.These 94%conventional reservoirs show promising exploration prospects in the deep area below buoyance-driven hydrocarbon accumulation depth.

Geological and Engineering‘Sweet Spots'in the Permian Lucaogou Formation,Jimusar Sag,Junggar Basin

Unconventional oil and gas resources require petrophysical logs to answer the question of how best to optimize geological and engineering‘sweet spots'.Therefore,the establishment of a key well with comprehensive descriptions of lithology,reservoir properties,hydrocarbon-bearing properties,electronic well log responses,source rock properties,brittleness,and in situ stress magnitude and direction is important for the effective exploration and production of unconventional hydrocarbon resources.Cores,thin sections,scanning electron microscopy(SEM)and comprehensive well log suites are used to build a key well for the Permian Lucaogou Formation,Jimusar Sag of the Junggar Basin.The results show that there are three main types of lithologies,including siltstone,mudstone and dolostone.Lithologies can be predicted using the combination of conventional well and image logs.The pore spaces consist of interparticle pores,intragranular dissolution pores and micropores.Nuclear Magnetic Resonance(NMR)T_(2)components longer than 1.7 ms are superposed as effective porosity.Permeability is calculated using the Coates model from NMR T_(2)spectra.The ratio of T_(2)components>7.0 ms to T_(2)components>0.3 ms is used to calculate oil saturation.TOC is calculated using theΔlog R method.Brittleness index is calculated using Poisson-Young's method,ranging from 13.42%-70.53%.In situ stress direction is determined,and in situ stress magnitudes(maximum horizontal stress SH_(max),minimum horizontal stress Sh_(min),vertical stress S_(v))are calculated using density and sonic logs.The strike-slip stress type(SH_(max)>S_(v)>Sh_(min))is encountered.The key well which comprehensively includes the above seven properties is established.Geological and engineering(geomechanical)‘sweet spots'are then optimized from the key well by fully analyzing lithology,reservoir property,oilbearing potential,in situ stress magnitude and brittleness.It is hoped that the results support engineers'and geologists'decisions for the future exploitation of unconventional hydrocarbon resources.

Numerical Study of Gas Production from a Methane Hydrate Reservoir Using Depressurization with Multi-wells

With the implementation of the production tests in permafrost and offshore regions in Canada,US,Japan,and China,the study of natural gas hydrate has progressed into the stage of technology development for industrial exploitation.The depressurization method is considered as a better strategy to produce gas from hydrate reservoirs based on production tests and laboratory experiments.Multi-well production is proposed to improve gas production efficiency,to meet the requirement for industrial production.For evaluating the applicability of multi-well production to hydrate exploitation,a 2D model is established,with numerical simulations of the performance of the multi-well pattern carried out.To understand the dissociation behavior of gas hydrate,the pressure and temperature distributions in the hydrate reservoir are specified,and the change in permeability of reservoir sediments is investigated.The results obtained indicate that multi-well production can improve the well connectivity,accelerate hydrate dissociation,enhance gas production rate and reduce water production as compared with single-well production.

Petroleum Distribution Characteristics of the Americas and the Exploration Prospect Analysis

The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.

全球页岩油形成分布潜力及中国陆相页岩油理论技术进展

全球非常规页岩层系油气资源丰富,富有机质页岩主要沉积在劳亚构造域和特提斯构造域的上侏罗统、渐新统—中新统、白垩系和上泥盆统4套页岩层系内。交汇分析北美典型页岩油区块产量与R_(o)数据关系,提出R_(o)为0.7%作为低熟页岩油和中高熟页岩油的界限,系统评价了全球116个盆地157套页岩层系中高熟页岩油、低熟页岩油技术可采资源量约2512亿t,主要分布在北美洲、南美洲、北非和俄罗斯,以前陆盆地中新界、克拉通盆地古生界、裂谷盆地和被动大陆边缘盆地的中生界为主。海相页岩油受显生宙以来的海侵影响,富集在稳定克拉通和前陆等类型盆地中,具大面积稳定分布、成熟度适中等特征;陆相页岩油受暖室期气候影响,主要在坳陷、断陷等类型盆地中发育,以微纳米级无机孔隙和微页理裂缝为主要储渗空间通道,具有沉积相横向变化大、“甜点区段”局部富集等特征。中国石油工业正经历从“陆相页岩生油”向“陆相页岩产油”转变,初步形成源岩油气“进源找油”地质理论、陆相页岩油高效勘探及低成本开发技术体系,推动中国陆相页岩油取得重要突破。着力加强应用基础理论研究与关键技术攻关,构建地质-工程一体化模式,强化全生命周期管理理念,加快中高熟页岩油“压裂人工油藏”工业化发展,加强低熟页岩油“加热原位转化”技术攻关与工业化试验,推动实现中国“陆相页岩油革命”,夯实“稳油增气”资源基础。

地应力测井评价方法及其地质与工程意义

地应力场研究可为井网部署、油气井压裂和裂缝有效性评价等提供理论指导与技术支撑,系统归纳地应力场分析以及测井评价方法流程至关重要。总结了地应力场构成及其测井响应机理,并指出对地应力响应较灵敏的测井序列为声波时差、电阻率和成像测井。在声发射实验确定古构造应力场期次及大小的基础上,通过电阻率、声波时差测井和裂缝密度恢复最大古构造应力。现今地应力场一般从地应力方向和大小两个方面进行描述,确定地应力方向的测井方法是成像测井拾取井壁崩落和诱导缝、阵列声波测井横波分裂,获取地应力场大小的手段是水力压裂法和声发射实验。在现今地应力场描述的基础上,利用组合弹簧模型等模型或方法计算现今地应力大小,实现地应力场分析。地应力场分析结果有助于更好地开展断层性质分析、储层质量和裂缝有效性评价以及油气藏分布预测,此外在非常规油气储层压裂改造等工程领域也有较大的应用价值。

新疆地区公益性油气调查进展与主要成果

新疆地区油气资源潜力巨大,是我国陆上油气增储上产的重点地区。“十三五”以来,公益性油气地质调查按照“盆地综合研究选方向、基础地质调查定区带、战略选区研究求突破”的工作思路,以深层—超深层、山前复杂构造带和非常规页岩油气为重点,持续加大新疆地区油气基础地质调查投入和科技攻关力度,取得了塔里木盆地深层地质结构调查1项重大进展和温宿凸起新近系、沙井子构造带志留系、塔西南和塔东南坳陷山前带侏罗系和准噶尔盆地博格达山周缘非常规页岩油气等4项油气调查重大发现和突破,形成了温宿地区“古隆起差异沉降控储控藏”、沙井子构造带“断裂主控、多期充注、晚期为主”和博格达山周缘“深部源储一体、浅部构造-岩性为主、多矿种环带分布”等3项地质理论认识,形成了“盆地级骨干地震大剖面资料拼接处理”“复杂山前带地震资料叠前目标处理解释”“广域电磁剖面测量及综合解释”等3项关键技术。支撑新疆地区油气勘查开采体制改革试点工作取得实效,带动企业实现高效勘探开发,提升了盆地深层、山前带及非常规页岩油气成藏理论认识水平,促进了地方经济和社会发展。

全球油气资源潜力与分布

采用以成藏组合为单元的常规、非常规油气资源评价方法,对全球主要含油气盆地(不含中国)的常规油气资源和7种类型的非常规资源油气地质与资源潜力进行评价,首次获得了具有自主知识产权的资源评价数据。经评价计算,全球常规石油可采资源量为5 350.0×10~8 t、凝析油可采资源量为496.2×10~8 t、天然气可采资源量为588.4×10^(12) m^3;其中剩余油气2P(证实储量+概算储量)可采储量为4 212.6×10~8 t,已知油气田可采储量增长量为1 531.7×10~8t,待发现油气可采资源量为3 065.5×10~8 t。全球非常规石油可采资源量为4 209.4×10~8 t、非常规天然气可采资源量为195.4×10^(12) m^3。评价结果表明,全球常规与非常规油气资源仍然丰富。

世界页岩气研究概况及中国页岩气资源潜力分析

页岩气系指泥岩或页岩在各种地质条件下生成的、已饱和岩石自身各种形式的残留需要、进入了排烃门限但尚未完全排出的以吸附、游离及溶解等多种形式残留于泥页岩内部的天然气资源。随着北美、欧洲和亚洲等地区页岩气勘探程度不断加大,对页岩气的储集特征、成藏机理等方面的研究取得重大进展。但页岩气研究仍存在许多问题,如"页岩气"概念没有科学地表达出页岩油气资源的科学内涵;页岩气的成因机制不清且缺乏行之有效的判别标准;页岩气分布发育模式不明且缺乏统一的预测方法。针对当前对页岩气的认识,本文依据源岩残留烃临界饱和量及其钻采过程中温压下降而释放油气的比率等参数,对中国页岩气资源进行了预测。

烃源岩非均质性及其意义——以中国元古界下马岭组页岩为例

以中国元古界下马岭组页岩为例,基于野外露头、镜下观察和地球化学特征分析,对不同尺度的烃源岩非均质性及烃类的微观赋存特征进行研究。岩石圈板块运动和古纬度位置导致烃源岩宏观旋回性和非均质性,天文轨道力控制的气候变化可能是导致烃源岩微观非均质性的最主要原因。因此,烃源岩非均质性是恒定存在的,不仅体现为有机质含量的差异,还包括碎屑物来源和孔隙度的差异。在油气资源评价,尤其是非常规油气资源评价时需要充分考虑烃源岩的非均质性。烃源岩非均质性特征为油气生成、排驱和储集提供了良好的"源储组合",为估算非常规油气经济可采储量提供了新的参考指标。因此烃源岩非均质性的定量化研究对非常规油气形成机理及资源量预测具有重要意义。

非常规油气储层脆性指数测井评价方法研究进展

非常规油气储层一般都需要进行压裂改造才能获得工业产能,而岩石脆性指数测井评价是非常规油气储层压裂设计中应考虑的重要因素之一。目前国内外关于脆性指数定义众多、且计算方法各异,在关于脆性指数的测井评价方法方面更是缺少一套完整的研究方法流程。本文回顾了油气储层脆性指数的研究历程,明确了脆性指数定义的科学内涵,归纳总结了脆性指数的测井评价方法。最后以鄂尔多斯盆地长7致密油储层为例,探讨了主要的脆性指数测井评价方法计算流程及其有效性。在有纵、横波测井资料时,可利用泊-杨法直接计算岩石脆性指数。同时也可通过元素俘获测井矿物成分比值法计算脆性指数。此外基于常规测井的最优化方法确定矿物组分,利用矿物成分比值法也能计算脆性指数。通过X-射线衍射资料与岩性系数GR/Pe的回归拟合建立地区经验公式,也可实现岩石脆性指数的测井评价。最后对脆性指数测井计算中存在的问题进行归纳总结,并对未来发展方向做出展望。研究成果可为非常规油气储层钻井和压裂设计工作提供科学指导。

非常规油气资源经济评价研究

非常规油气资源已成为重要的战略接替资源,且由于独特的形成、富集与分布规律,非常规油气资源并不能使用常规的方法进行开采.首先对油气资源经济评价进行定义,在此基础上将常规油气资源经济评价广泛使用的净现值法与实物期权法进行对比,针对非常规油气资源的特点,该案例研究构建以实物期权法为基础的非常规油气资源经济评价方法,通过对西部某省份非常规油气资源勘探开发投资项目进行分析,结果显示:当前应该持有资产以待开发;第一年无论价格是上升还是下降,都选择持有资产以期获取更大的收益;第二年在价格上涨的趋势下,非常规油气资源理应立即开发,如果价格下跌,则继续持有.该案例研究为非常规油气资源勘探开发投资项目不同阶段应该选择持有以待开发还是立即开发提供了依据,验证了以实物期权为基础的非常规油气资源经济评价方法的适用性.