Regression analysis and its application to oil and gas exploration:A case study of hydrocarbon loss recovery and porosity prediction,China

In oil and gas exploration,elucidating the complex interdependencies among geological variables is paramount.Our study introduces the application of sophisticated regression analysis method at the forefront,aiming not just at predicting geophysical logging curve values but also innovatively mitigate hydrocarbon depletion observed in geochemical logging.Through a rigorous assessment,we explore the efficacy of eight regression models,bifurcated into linear and nonlinear groups,to accommodate the multifaceted nature of geological datasets.Our linear model suite encompasses the Standard Equation,Ridge Regression,Least Absolute Shrinkage and Selection Operator,and Elastic Net,each presenting distinct advantages.The Standard Equation serves as a foundational benchmark,whereas Ridge Regression implements penalty terms to counteract overfitting,thus bolstering model robustness in the presence of multicollinearity.The Least Absolute Shrinkage and Selection Operator for variable selection functions to streamline models,enhancing their interpretability,while Elastic Net amalgamates the merits of Ridge Regression and Least Absolute Shrinkage and Selection Operator,offering a harmonized solution to model complexity and comprehensibility.On the nonlinear front,Gradient Descent,Kernel Ridge Regression,Support Vector Regression,and Piecewise Function-Fitting methods introduce innovative approaches.Gradient Descent assures computational efficiency in optimizing solutions,Kernel Ridge Regression leverages the kernel trick to navigate nonlinear patterns,and Support Vector Regression is proficient in forecasting extremities,pivotal for exploration risk assessment.The Piecewise Function-Fitting approach,tailored for geological data,facilitates adaptable modeling of variable interrelations,accommodating abrupt data trend shifts.Our analysis identifies Ridge Regression,particularly when augmented by Piecewise Function-Fitting,as superior in recouping hydrocarbon losses,and underscoring its utility in resource quantification refinement.Meanwhile,Kernel Ridge Regression emerges as a noteworthy strategy in ameliorating porosity-logging curve prediction for well A,evidencing its aptness for intricate geological structures.This research attests to the scientific ascendancy and broad-spectrum relevance of these regression techniques over conventional methods while heralding new horizons for their deployment in the oil and gas sector.The insights garnered from these advanced modeling strategies are set to transform geological and engineering practices in hydrocarbon prediction,evaluation,and recovery.

Hydrocarbon accumulation and orderly distribution of whole petroleum system in marine carbonate rocks of Sichuan Basin,SW China

Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.

Prospective prediction and exploration situation of marine Mesozoic-Paleozoic oil and gas in the South Yellow Sea

The South Yellow Sea Basin is a large sedimentary basin superimposed by the Mesozoic-Paleozoic marine sedimentary basin and the Mesozoic-Cenozoic terrestrial sedimentary basin, where no oil and gas fields have been discovered after exploration for 58 years. After the failure of oil and gas exploration in terrestrial basins, the exploration target of the South Yellow Sea Basin turned to the marine Mesozoic- Paleozoic strata. After more than ten years' investigation and research, a lot of achievements have been obtained. The latest exploration obtained effective seismic reflection data of deep marine facies by the application of seismic exploration technology characterized by high coverage, abundant low-frequency components and strong energy source for the deep South Yellow Sea Basin. In addition, some wells drilled the Middle-Upper Paleozoic strata, with obvious oil and gas shows discovered in some horizons. The recent petroleum geological research on the South Yellow Sea Basin shows that the structure zoning of the marine residual basin has been redetermined, the basin structure has been defined, and 3 seismic reflection marker layers are traceable and correlatable in the residual thick Middle-Paleozoic strata below the continental Meso-Cenozoic strata in the South Yellow Sea Basin. Based on these, the seismic sequence of the marine sedimentary strata was established. According to the avaliable oil and gas exploration and research, the marine Mesozoic-Paleozoic oil and gas prospects of the South Yellow Sea were predicted as follows.(1) The South Yellow Sea Basin has the same sedimentary formation and evolution history during the sedimentary period of the Middle-Paleozoic marine basin with the Sichuan Basin.(2) There are 3 regional high-quality source rocks.(3) The carbonate and clastic reservoirs are developed in the Mesozoic- Paleozoic strata.(4) The three source-reservoir-cap assemblages are relatively intact.(5) The Laoshan Uplift is a prospect area for the Lower Paleozoic oil and gas, and the Wunansha Uplift is one for the marine Upper Paleozoic oil and gas.(6) The Gaoshi stable zone in the Laoshan Uplift is a favorable zone.(7) The marine Mesozoic-Paleozoic strata in the South Yellow Sea Basin has the geological conditions required to form large oil and gas fields, with remarkable oil and gas resources prospect. An urgent problem to be addressed now within the South Yellow Sea Basin is to drill parametric wells for the Lower Paleozoic strata as the target, to establish the complete stratigraphic sequence since the Paleozoic period, to obtain resource evaluation parameters, and to realize the strategic discovery and achieve breakthrough in oil and gas exploration understanding.

Tectonic-thermal history and hydrocarbon potential of the Pearl River Mouth Basin,northern South China Sea:Insights from borehole apatite fission-track thermochronology

The Pearl River Mouth Basin(PRMB)is one of the most petroliferous basins on the northern margin of the South China Sea.Knowledge of the thermal history of the PRMB is significant for understanding its tectonic evolution and for unraveling its poorly studied source-rock maturation history.Our investigations in this study are based on apatite fission-track(AFT)thermochronology analysis of 12 cutting samples from 4 boreholes.Both AFT ages and length data suggested that the PRMB has experienced quite complicated thermal evolution.Thermal history modeling results unraveled four successive events of heating separated by three stages of cooling since the early Middle Eocene.The cooling events occurred approximately in the Late Eocene,early Oligocene,and the Late Miocene,possibly attributed to the Zhuqiong II Event,Nanhai Event,and Dongsha Event,respectively.The erosion amount during the first cooling stage is roughly estimated to be about 455-712 m,with an erosion rate of 0.08-0.12 mm/a.The second erosion-driven cooling is stronger than the first one,with an erosion amount of about 747-814 m and an erosion rate between about 0.13-0.21 mm/a.The erosion amount calculated related to the third cooling event varies from 800 m to 3419 m,which is speculative due to the possible influence of the magmatic activity.

Driving forces and their relative contributions to hydrocarbon expulsion from deep source rocks: A case of the Cambrian source rocks in the Tarim Basin

To thoroughly understand the dynamic mechanism of hydrocarbon expulsion from deep source rocks,in this study,five types of hydrocarbon expulsion dynamics(thermal expansion,hydrocarbon diffusion,compaction,product volume expansion,and capillary pressure difference(CPD))are studied.A model is proposed herein to evaluate the relative contribution of different dynamics for hydrocarbon expulsion using the principle of mass balance,and the model has been applied to the Cambrian source rocks in the Tarim Basin.The evaluation results show that during hydrocarbon expulsion from the source rocks,the relative contribution of CPD is the largest(>50%),followed by compaction(10%-40%),product volume expansion(5%-30%),and thermal expansion(2%-20%).The relative contribution of diffusion to hydrocarbon expulsion is minimal(<10%).These results demonstrate that CPD plays an important role in the hydrocarbon expulsion process of deep source rocks.The hydrocarbon expulsion process of source rocks can be categorized into three stages based on the contribution of different dynamics to the process:the first stage is dominated by compaction and diffusion to expel hydrocarbons,the second stage is dominated by product volume expansion and CPD,and the third stage is dominated by product volume expansion and CPD.This research offers new insights into hydrocarbon exploration in tight oil and gas reservoirs.

Surface Geochemical Patterns over Oil and Gas Traps

Surface geochemical exploration for oil and gas is still in the empirical stage , despite 50 years has passed since the method was first proposed by Laubmeyer and Sokolov . A boom of its application is emerging in China followed the depression during 60 - 70 's . However , before the method can be accepted by the industry as a routine technique , a relatively sound basis should be established . This paper presents several cases over known oil and gas fields and discusses the factors that effect the surface geochemical expression of underground oil pools .

Main progress and problems in research on Ordovician hydrocarbon accumulation in the Tarim Basin

The Tarim Basin is the largest petroliferous basin in the northwest of China, and is composed of a Paleozoic marine craton basin and a Meso-Cenozoic continental foreland basin. It is of great significance in exploration of Ordovician. In over 50 years of exploration, oil and gas totaling over 1.6 billion tonnes oil-equivalent has been discovered in the Ordovician carbonate formation. The accumulation mechanisms and distribution rules are quite complicated because of the burial depth more than 3,500 m, multi-source, and multi-stage accumulation, adjustment, reconstruction and re-enrichment in Ordovician. In this paper, we summarized four major advances in the hydrocarbon accumulation mechanisms of Ordovician carbonate reservoirs. First, oil came from Cambrian and Ordovician source rocks separately and as a mixture, while natural gas was mainly cracked gas generated from the Cambrian-Lower Ordovician crude oil. Second, most hydrocarbon migrated along unconformities and faults, with different directions in different regions. Third, hydrocarbon migration and accumulation had four periods： Caledonian, early Hercynian, late Hercynian and Himalayan, and the latter two were the most important for oil and gas exploration. Fourth, hydrocarbon accumulation and evolution can be generally divided into four stages： Caledonian （the period of hydrocarbon accumulation）, early Hercynian （the period of destruction）, late Hercynian （the period of hydrocarbon reconstruction and re-accumulation）, and Himalayan （the period of hydrocarbon adjustment and re-accumulation）. Source rocks （S）, combinations of reservoir-seal （C）, paleo-uplifts （M）, structure balance belt （B） matched in the same time （T） control the hydrocarbon accumulation and distribution in the Ordovician formations. Reservoir adjustment and reconstruction can be classified into two modes of physical adjustment and variation of chemical compositions and five mechanisms. These mechanisms are occurrence displacement, biodegradation, multi-source mixing, high-temperature cracking and late gas invasion. Late hydrocarbon accumulation effects controlled the distribution of current hydrocarbon. The T-BCMS model is a basic geological model to help understanding the control of reservoirs. At present, the main problems of hydrocarbon accumulation focus on two aspects, dynamic mechanisms of hydrocarbon accumulation and the quantitative models of oil-bearing in traps, which need further systemic research.

Prospects of borehole NMR instruments and applications Dedicated to Professor Chaohui Ye on the occasion of his 80th birthday

Borehole nuclear magnetic resonance(NMR)is a powerful technology to characterize the petrophysical properties of underground reservoirs in the petroleum industry.The rising complexity of oil and gas exploration and development objectives,as well as the novel application contexts of underground reservoirs,have led to increasingly demanding requirements on borehole NMR technology including instrument design and related processing methods.This mini review summarizes the advances and applications of borehole NMR instruments along with some future possibilities.It may be helpful for researchers and engineers in the petroleum industry to understand the development status and future trends of borehole NMR technology.

Sequence stratigraphic framework and sedimentary model of Shanxi Formation in northeast Zhoukou Depression of the North China Plate

The sequence stratigraphic framework of Shanxi Formation in the northeast Zhoukou Depression was established based on detailed sequence stratigraphical and sedimentological analysis by utilizing the logging and core data of six wells drilled in the eastern tectonic unit of Zhoukou Depression.It was divided into three third-order sequences,namely SQs1,SQs2,and SQs3 from bottom to top.Each sequence can be divided into a transgressive system tract(TST)and a highstand system tract(HST).Furthermore,four sequence boundaries and three maximum flooding surfaces were identified,and they are the bottom interface SBs and maximum flooding surface mfss1 of SQs1,the bottom interface SBs1 and maximum flooding surface mfss2 of SQs2,the bottom interface SBs3 and maximum flooding surface mfss3 of SQs3,and the top interface SBx from bottom to top.Carbonate tidal flat–clastic tidal flat sedimentary system developed in Shanxi Formation in the northeast Zhoukou Depression(also referred to as the study area)under the control of regression.Meanwhile,four sedimentary microfacies were identified in the sedimentary system,which are lime-mud flats,sand flats,mixed flats,and mud flats.The transgression in the study area occurred from the southeast to the northwest.Therefore,the northwestern part is the seaward side,and the southeastern part is the landward side.As revealed by relevant drilling data,SQs1 of the Shanxi Formation is characterized by the development of limestone and carbonaceous mudstone,with limestone,dark mudstone,and carbonaceous mudstone mainly developing.Meanwhile,lime-mud flats were mainly deposited in it.During the periods of SQs2 and SQs3,the sedimentary environment of the study area changed from the carbonate tidal flats to clastic tidal flats as the coastline migrated towards the sea.In these periods,sand flats mainly developed near the maximum flooding surfaces and were relatively continuous in the eastern and southern parts of the transgressive system tract;mixed flats were relatively continuous in the western and northern parts of the transgressive system tract as well as the eastern and southern parts of the highstand system tract;mud flats widely developed in the highstand system tract.Peat flats mainly developed in the period of HSTs2,with coal seams relatively developing in the southeastern part of the study area as revealed by drilling data.The peat flats in SQs2 are favorable hydrocarbon source layers,the lime-mud flats in SQs1 and sand flats formed in the transgression periods of SQs2 and SQs3 constitute favorable hydrocarbon reservoirs,and the mud flats form in the transgressions periods serve as favorable cap rocks.Therefore,the study area features a reservoir-cap assemblage for self-generating and self-storing of hydrocarbon,and the southeastern part of the study area can be taken as a favorable exploration area.

New progress of microbial prospecting of oil and gas in China:Taking the Satellite Oilfield in Daqing as an example

The Microbial Prospecting of Oil and Gas(MPOG) is applied to the matured development area in the Satellite Oilfield in Daqing for the first time. And with the MPOG,the hydrocarbon accumulation regulation controlled by faults is interpreted,and the matured development area is extended out to western part. At the same time,four microbial anomalies are discovered. The MPOG results were verified by the hydrocarbon-bearing conditions of the 10 drilled wells within the following half a year,and the consistent rate is up to 80%,which add about 300×104 t of the explored petroleum-in-place. Through study and successful application of MPOG to the Satellite Oilfield,the basis of the application from the exploration to development field is substantially established,and standard system of microbial anomaly is more precisely built for the Satellite Oilfield,which provided an effective explanatory item for the studied and adjacent region,even for the whole Songliao Basin,and also a new technique for complicated reservoirs,especially for the later stage development of litho-reservoirs in China. Therefore,it must have profound influence upon the oil and gas exploration,especially upon the remaining oil,extension and reserves addition of the developed area in China.

Hydrocarbon accumulation conditions and key exploration and development technologies for PL 19-3 oilfield

The PL 19e3 Oilfield is the only super-large monolithic oilfield with oil and gas reserves up to 1×10^(9) t in the Bohai Bay Basin,and it has been successfully developed.Exploration and development practices have provided abundant data for analyzing formation conditions of this super-large oilfield.On the basis of the exploration and development history,fundamental reservoir features,and with available geological,geophysical and test data,the hydrocarbon accumulation conditions and key exploration&development technologies of the PL 19e3 Oilfield were discussed.The key conditions for forming the super-large Neogene oilfield include four aspects.Firstly,the oilfield is located at the high position of the uplift that contacts the brachy-axis of the multi-ridge slope in the biggest hydrocarbon-rich sag in the Bohai Bay Basin,thus it has sufficient hydrocarbon source and extremely superior hydrocarbon migration condition.Secondly,the large-scale torsional anticlines which formed in the Neogene under the control of the Tanlu strike-slipping movement provide sufficient storage spaces for oil and gas preservation.Thirdly,the“multiple sets of composite reservoir-caprock assemblages”developing in the special shallow-water delta further contributes greatly to the effective storage space for oil and gas preservation.Fourthly,due to the coupling of the uplift and strike slip in the neotectonic period,extensive faulting activities constantly released the pressure while the late period massive hydrocarbon expulsion of the Bozhong took place at the same time,which assures the constant and intense charging of oil and gas.The super-large PL 19e3 Oilfield was controlled by the coupling effects of all those special geologic factors.In view of this oilfield's features(e.g.violently reformation caused by strike slip,and the special sedimentary environment of shallow-water delta),some key practical technologies for exploration and development have been developed.Such technologies include:the special prestack depth migration processing for gas cloud zones,the prediction of thin interbed reservoirs based on high-precision inversion of geologic model,the reservoir description for the shallow-water braided river delta,the quantitative description for remaining oil in the commingled oil reservoirs with wide well spacing and long well interval,and the well pattern adjustment for formations during high water cut period in the complex fluvial-facies oilfields.

The surface geochemical exploration of oil and gas in the Gangbatong-Ya'anxiang and the Dongqiao-Nam Co of the Qinghai-Tibet region

Due to the complexity of geological background and the adverseness of natural geographical environment in the Qinghai-Tibet Plateau,it is very difficult to carry out petroleum geological study in this region. The Qinghai-Tibet Plateau is the only blank space of petroleum exploration on a large scale. The authors carried out the surface geochemical exploration of oil and gas in the Gangbatong-Ya'anxiang and Dongqiao-Nam Co of the Qinghai-Tibet region. Based on the data of actual detection and experiments in the studied area,the characteristics of concentration and profile distribution of the main geochemical exploration indicators(total adsorbed hydrocarbon,altered carbonate,thermal released mercury,etc.) were discussed. The origin of hydrocarbon was also discussed. Moreover,the oil and gas potential of different sections in the Qiangtang Basin and the Biru Basin were evaluated,which could provide references for the exploration and prediction of oil and gas in this region. The concentrations of total adsorbed hydrocarbons in the Ya'anxiang of Suoxian County-Zadong of Baqing County and the Jiecha-Dangxiong of Anduo County in the Qinghai-Tibet region are high,averaging 312.64 μL·kg-1 and 164.36 μL·kg-1. Their altered carbonate concentrations are relatively low,averaging 0.11% and 0.56%. Their concentrations of thermal released mercury are relatively high,averaging 13.09×10-9 and 1.94×10-9. Geochemical exploration results in fact reflect hydrocarbon information in the underground,which are mainly petroleum associated gas and over-matured cracking gas. The Jiecha-Charenluma and the Xiamaya'ertong-Suoba sections in the Qiangtang Basin are the most favorable ones for oil and gas and the Ekou-Zadong section is relatively favorable one,while the Nam Co and the Zigetangcuo-Dongqiao sections in the Biru Basin are the favorable ones for oil and gas,and the Jiang Co-Nading Co and the Ya'anxiang-Ya'ertong sections are relatively favorable ones.

Petroleum Exploration of Craton Basins in China

Craton basins are a significant petroliferous provenance. Having undergone multiple open- dose tectonic cycles and strong reworking of the late Cenozoic tectonic movement, the craton basins in China are highly broken. This has resulted in multi-source and multiphase hydrocarbon generation and later hydrocarbon accumulation so that a complicated spatial assemblage of primary, paraprimary and secondary oil-gas pools has been formed. The primary factors controlling hydrocarbon accumulation include hydrocarbon-generating depressions, paleouplifts, paleoslopes, unconformity surfaces, paleo-karst, faults and fissure systems as well as the later conservation conditions. In consequence, the strategy of exploration for China＇s craton basins is to identify the effective source rocks, pay attention to the different effects of paleohighs and late reworking, enhance studies of the secondary storage space, attach importance to the exploration of lithologic oil-gas reservoirs and natural gas pools, and approach consciously from the secondary oil pools to the targets near the source rocks. At the same time, a complete system of technologies and techniques must be built up.

利用重磁资料研究北极地区扬马延微陆块中南部断裂构造与油气远景

为了研究北极地区扬马延微陆块中南部的断裂构造与油气远景,系统收集并整理了已有的重力及磁力资料,基于变纬度化极技术计算磁力化极异常,利用位场边缘识别技术获得相应的位场边缘识别信息,结合已有的地质及地球物理研究成果,对重磁异常及位场边缘识别信息进行深入分析,确定扬马延微陆块中南部断裂构造格架,圈定油气勘探有利区。研究认为,扬马延微陆块中南部重力高异常与重力低异常相间分布的特征反映了该区隆起与坳陷分布的范围及展布特征。扬马延微陆块中南部主要发育有北东向、北西向、近东西向及近南北向4组断裂,这4组断裂对基底结构、性质、隆坳格架及新生界分布起着重要的控制作用。扬马延微陆块中南部圈定出Ⅰ类和Ⅱ类油气勘探有利区,这些勘探有利区最显著的特征是处于自由空间重力局部异常及垂向二阶导数异常高值带,其发育明显受断裂构造控制。Ⅰ类勘探有利区对应的重力异常幅值较高、异常变化梯度较陡;相对于Ⅰ类勘探有利区,Ⅱ类勘探有利区对应的重力异常幅值相对较小、异常变化梯度相对较为平缓。

Theory, Technology and Practice of Unconventional Petroleum Geology

0 INTRODUCTION The breakthroughs in unconventional petroleum have a great impact on world petroleum industry and innovation in petroleum geology(Dou et al,2022;Jia,2017;Zou et al.,2015b,2014a;Yerkin,2012;Pollastro,2007;Schmoker,1995).The exploration and development evolution from conventional petroleum to unconventional petroleum and more and more frequent industrial activities of exploring petroleum inside sources kitchen have deepened theoretical understanding of unconventional petroleum geology and promoted technical research and development(Jia et al.,2021,2017;Jin et al.,2021;Zhao W Z et al.,2020;Ma Y S et al.,2018,2012;Zou et al.,2018b,2016,2009;Dai et al.,2012).We have introduced and extended the theory of continuous hydrocarbon accumulation since 2008 and published several papers/books(in Chinese and English)with respect to unconventional petroleum geology since 2009,basically forming the theoretical framework for this discipline(Yang et al.,2022a,2021a,2019a,,2015a;Zou et al.,2019c,2017b,2014a,,2013a).In this paper,we present the background of unconventional petroleum geology,review the latest theoretical and technological progress in unconventional petroleum geology,introduce relevant thinking and practices in China,and explore the pathway of unconventional petroleum revolution and multi-energy coordinated development in super energy basins,hopefully to promote the unconventional petroleum geology and industry development.

中国南方盆地覆盖类型及油气成藏

根据盆地演化及生储盖组合特征,将中国南方盆地叠合关系分为覆盖型(连续覆盖型、间断覆盖型)和非覆盖型(下组合保持型、上组合保持型)。不同的覆盖关系对烃类的生成、演化、运移、保存或破坏有不同程度的影响。在不同覆盖类型的盆地中,以连续覆盖型盆地的油气勘探前景最为优越;具有间断覆盖特点的江汉南部的沉湖—土地堂复向斜和苏北盆地的南陵—句容—海安区块,其地质条件较为有利;上组合保持型覆盖地区的油气前景值得认真研究和探索,就保存条件来说,阿坝地区勘探前景优于南盘江地区;下组合保持型地区也具有良好的油气勘探远景;对于那些由于大型推覆构造所形成的特殊覆盖关系地区,下盘海相地层中的油气成藏和勘探值得重视。

我国重点盆地致密油气资源潜力评价

我国致密油气勘探开发在鄂尔多斯盆地、四川盆地、松辽盆地、准噶尔盆地等盆地取得了一系列新发现和新突破,储量和产量快速增长,是现阶段最现实的非常规油气资源。梳理总结致密油气勘探开发进展,采用三大类七种评价方法,对10个重点含油气盆地致密油气资源进行评价,计算得到致密油地质资源量146.60×10~8 t,可采资源量14.55×10~8 t,致密气地质资源量22.88×10^(12) m^3,可采资源量11.26×10^(12) m^3。综合分析认为,我国致密油气资源丰富、潜力大,尽管面临技术成本等挑战,但是抓住新形势和新机遇,具有良好的勘探开发前景。

南海北部莺歌海盆地与琼东南盆地油气成藏条件比较研究

莺歌海盆地与琼东南盆地位于南海北部大陆边缘西部,两盆地虽仅以①号断层相隔,但其油气成藏特征差异明显:莺歌海盆地以中新统三亚—梅山组和上新统底部莺歌海组海相泥岩为主要烃源岩,而琼东南盆地主要烃源岩为渐新统崖城—陵水组近海含煤岩系;泥底辟活动产生的大量垂向断层、裂缝是莺歌海盆地油气垂向运移的主要通道,而琼东南盆地西区则以侧向输导为主,东区兼有垂向和侧向输导特征;莺歌海盆地中新世晚期泥底辟背斜、披覆背斜、断块等构造圈闭及地层岩性圈闭是油气聚集的主要圈闭类型,琼东南盆地则以古近纪构造圈闭为主、新近纪地层岩性圈闭为辅。认为莺歌海盆地下含气系统具有巨大资源潜力,是未来油气勘探的主要靶区;琼东南盆地的主要勘探领域应放在古近系和能与古近系连通的新近纪岩性—构造复合圈闭上,深水区则是该盆地非常重要的油气勘探新领域。

西非被动大陆边缘Walvis Ridge以南纳米比亚盆地的地质特征及油气意义——兼与Walvis Ridge以北盆地比较

西非被动大陆边缘近海盆地区是世界关注的油气产区和投资热点地区之一,但目前为止的油气产出主要集中在Walvis Ridge以北的盆地区(北部盆地区),而以南的纳米比亚盆地区只发现了一个Kudu气田。从西非被动边缘的构造演化历史、边缘结构特征等方面,通过纳米比亚盆地与北部产油气盆地间的比较,对纳米比亚近海盆地区的油气勘探前景进行了有益的探讨。综合分析后认为,纳米比亚近海盆地区油气勘探没有大的突破的主要原因是受政治影响、勘探程度低及公布资料较少、研究程度低。从边缘演化特征来看,纳米比亚盆地区裂谷作用及海底扩张方式、边缘结构等与北部盆地区十分相似,只不过时间上略早。南、北盆地区都经历了前裂谷期、同裂谷期、过渡期和后裂谷期等几个发育时期,形成了类似的构造—沉积组合,发育类似的烃源岩层(除与北部盆地区类似的烃源岩层外,纳米比亚边缘Karoo期前裂谷期沉积可能也是潜在烃源岩)。成熟度和热史模拟认为,纳米比亚边缘离开海岸线一定距离内油气成熟度达到中、高度,具备了油气生成条件,而储盖层及对西非产油意义较大的蒸发岩也较发育,漂移期地层中发育的重力滑动构造可形成大型构造圈闭并对漂移期浊积岩分布有控制作用。综合分析后认为,纳米比亚盆地区与北部盆地区具十分相似的地质背景,具备了形成油气的条件,应加强勘探与研究工作,而纳米比亚近海盆地离开岸线一定范围是油气勘探的优选目标区。