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.

Features of Sandy Debris Flows of the Yanchang Formation in the Ordos Basin and Its Oil and Gas Exploration Significance

Sandy debris flow is a new genetic type of sand bodies,which has gained much attention in recent years and its corresponding theory is proved to be a significant improvement and even partial denial to the 'Bouma Sequence' and 'turbidite fan' deep-water sedimentary theories to some point. Oil exploration researchers are highly concerned with sandy debris flows for its key role in controlling oil and gas accumulation processes.In this article,by applying sandy debris flows theory and combining a lot work of core,outcrop observation and analysis plus seismic profile interpretation,we recognized three types of sedimentary gravity flows that are sandy debris flows,classic turbidites and slumping rocks in chang-6 member of Yanchang Formation in the deep-water area of central Ordos Basin.Among the three types,the sandy debris flows are the most prominent and possesses the best oil bearing conditions.On the contrary,the classic turbidites formed by turbidity currents are limited in distribution;therefore,previous Yanchang Formation deep-water sedimentary studies have exaggerated the importance of turbidite currents deposition.Further study showed that the area distribution of deep water gravity flow sand bodies in Yanchang Formation were controlled by the slope of the deep-water deposits and the flows had vast distribution,huge depth and prevalent advantages for oil forming,which make it one of the most favorable new areas for Ordos Basin prospecting.

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.

BTEX anomalies used as indicators of submarine oil and gas reservoirs

It is a conventional method for petroleum prospecting to generally use paraffin hydrocarbon as basic indexes of oil and gas. This conventional geochemical technology, however, shows some limits in the prospecting as paraffin is vulnerable to influences from human and biologic activities. Consequently, BTEX （short for benzene, toluene, ethyl benzene and xylem, which are direct biomarkers） among aromatic hydrocarbon series has been taken into account for the oil and gas prediction. Domestic and foreign study results demonstrate that BTEX is hardly disturbed and can well indicate oil and gas reservoirs. Based on measured data from a South China Sea area, the present authors have used self-developed visual assessment software for petroleum prospecting has been used to process data, strip background anomalies, and outline significant BTEX anomalies. By comparison with stratigraphic profiles of the target area, it is confirmed that BTEX is a good indication of marine oil and gas during the petroleum prospecting.

Discovery of Palaeozoic Karsts in the Qaidam Basin and Their Oil and Gas Prospects

Objective Complex geological factors have been constraining the oil and gas exploration in the Paleozoic strata of the Qaidam Basin,although there are high-quality hydrocarbon source rocks.One of the most important reasons may be reservoir densification due to the multiple stages of destructive cementation,which has hindered our understanding of the Paleozoic petroleum enrichment rules in the Qaidam basin.In recent years.

Microbial Gas in the Mohe Permafrost, Northeast China and its Significance to Gas Hydrate Accumulation in Permafrost across China

The Mohe permafrost in northeast China possesses favorable subsurface ambient temperature, salinity, Eh values and pH levels of groundwater for the formation of microbial gas, and the Mohe Basin contains rich organic matter in the Middle Jurassic dark mudstones. This work conducted gas chromatography and isotope mass spectrometry analyses of nearly 90 core gas samples from the Mk-2 well in the Mohe Basin. The results show that the dryness coefficient(C1/C1–5) of core hydrocarbon gas from approximately 900 m intervals below the surface is larger than 98%, over 70% of the δ13 C values of methane are smaller than-55‰, and almost all δD values of methane are smaller than-250‰, indicative of a microbial origin of the gas from almost 900 m of the upper intervals in the Mohe permafrost. Moreover, the biomarker analyses of 72 mudstone samples from the Mohe area indicate that all of them contain 25-norhopane series compounds, thereby suggesting widely distributed microbial activities in the permafrost. This work has confirmed the prevailing existence of microbial gas in the Mohe area, which may be a potential gas source of gas hydrate formation in the Mohe permafrost. This result is of great significance to gas hydrate accumulation in the permafrost across China.

DEFINITING AND ITS GEOLOGIC MEANING OF SOUTH-NORTH TREND FAULTED STRUCTURE BELT IN QIANGTANG BASIN, NORTH PART OF TIBET

There were more expounding to north—west (west) trend fault and north\|east trend fault within Qiangtang Basin, North Part of Tibet, in the past literature. With increasing of geophysical exploration data, nearly east\|west trend structure began to be taken note to. Since the year of 1995, by a synthetic study to geophysical and geological data, that south\|north trend faulted structures are well developed. These structures should be paid much more attention to, because they have important theoretical meaning and practical significance.1 Spreading of south\|north faulted structure belt According to different geological and geophysical data, the six larger scale nearly south\|north faulted structure belt could be distinguished within the scope of east longitude 84°～96° and near Qiangtang Basin. The actual location of the six belts are nearly located in the west of the six meridian of east longitude 85°,87°,89°,91°,93°,95° or located near these meridian. The six south\|north faulted structure belts spread in the same interval with near 2° longitude interval. The more clear and much more significance of south\|north trend faulted structure belts are the two S—N trend faulted structure belts of east longitude 87° and 89°. There are S—N trend faulted structure belts in the west of east longitude 83°,81°, or near the longitudes. The structure belts spreading features,manifestation,geological function and its importance, and inter texture and structure are not exactly so same. The structure belts all different degree caused different region of geological structure or gravity field and magnetic field. There is different scale near S—N trend faulted structure belt between the belts.

Structural Characteristics and Evolution of Jurassic Basins in the East of Middle Qilian Block

Structural characteristics of the Jurassic basins of Xining, Minhe, and Xiji in the east of middle Qilian were researched based on the data obtained by gravitational, magnetic, and seismic methods. The result shows that each of these three basins is an independent structural unit with a NW strike and being separated by upheavals. Two groups of faults with NW and NE directions are developed in the basin, which controls the formation and evolution of the (Jurassic basins). The NW faults are the main ones while the NE faults are the secondary for controlling the sedimentation. Of the three basins, the Minhe basin is the favorable prospecting area.

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.

Deep structure of the Kumkol basin in the northern Tibetan Plateau and its resource environmental implications

The Kumkol basin is located in the northern Tibetan Plateau and is a closed plateau basin with an average altitude of>4000 m and an area of nearly 20000 km^(2). Its boundaries are limited by the Altyn Tagh fault, East Kunlun orogen and Qimantag orogen. Studying the deep structure of the Kumkol basin reveals 2 significant implications:(1) the basin has developed a large thickness of >7000 m Cenozoic continental sediments, recording the uplift history of the northern Tibetan Plateau, and(2)preliminary work indicates that the basin is likely to have oil and gas prospects. However, owing to the adverse natural conditions of the area and the strong tectonic activity in the Cenozoic, the latter of which was not conducive to hydrocarbon preservation,only regional geological mapping and petroleum exploration route surveys have been carried out, and there is no consensus on strata, structure and tectonic evolution. From 2021 to 2022, a deep seismic reflection profile implemented by the Second Tibetan Plateau Scientific Expedition and Research(STEP) project was the first high-resolution geophysical survey across the Kumkol basin. This study uses seismic reflection migration profiles, first-arrival wave tomographic imaging and previous research results to analyze the deep structure of the basin. The final merged model contains many features of tectonic and resource significance:(1) The Kumkol basin is ~90 km wide from north to south, with a basement depth of >9000 m. The main component is the Cenozoic continental deposits, which are divided into two major parts: the southern composite basin and the northern faulted basin. Owing to the later compression, the southern composite basin experienced significant deformation, but most parts still preserved their original sedimentary formations.(2) The structural deformation characteristics of the basin reveal a two-stage tectonic evolution process of the northern Tibetan Plateau in the Cenozoic: from the Oligocene to the Pliocene, the main mechanism was vertical differential uplift and subsidence, and after the Pliocene, it transformed to north-south compression and shortened deformation.(3) The strata, formation time, and source-reservoir-cap conditions of the Kumkol basin are similar to those of the Qaidam basin. If a breakthrough can be achieved, it is expected to expand the production capacity of the oil field in the Qaidam basin with a low-cost investment. Thus, further exploration is recommended.

A Mutant Strain of a Surfactant-Producing Bacterium with Increased Emulsification Activity

As reported in this paper, a strain of oil-degrading bacterium Sp - 5 - 3 was determined to belong to Enterobacteriaceae, which would be useful for microbial enhanced oil recovery (MEOR). The aim of our study was to generate a mutant using low energy N+ beam implantation. With 10 keV of energy and 5.2× 1014 N+/cm2 of dose - the optimum condition, a mutant, S-34, was obtained, which had nearly a 5-fold higher surface and a 13-fold higher of emulsifica-tion activity than the wild type. The surface activity was measured by two methods, namely, a surface tension measuring instrument and a recording of the repulsive circle of the oil film; the emulsification activity was scaled through measuring the separating time of the oil-fermentation mixture. The metabolic acid was determined as methane by means of gas chromatography.

Research achievements of the Qinghai-Tibet Plateau based on 60 years of aeromagnetic surveys

The Qinghai-Tibet Plateau(also referred to as the Plateau)has long received much attention from the community of geoscience due to its unique geographical location and rich mineral resources.This paper reviews the aeromagnetic surveys in the Plateau in the past 60 years and summarizes relevant research achievements,which mainly include the followings.(1)The boundaries between the Plateau and its surrounding regions have been clarified.In detail,its western boundary is restricted by West Kunlun-Altyn Tagh arc-shaped magnetic anomaly zone forming due to the arc-shaped connection of the Altyn Tagh and Kangxiwa faults and its eastern boundary consists of the boundaries among different magnetic fields along the Longnan(Wudu)-Kangding Fault.Meanwhile,the fault on the northern margin of the Northern Qilian Mountains serves as its northern boundary.(2)The Plateau is mainly composed of four orogens that were stitched together,namely East Kunlun-Qilian,Hoh-Xil-Songpan,Chamdo-Southwestern Sanjiang(Nujiang,Lancang,and Jinsha rivers in southeastern China),and Gangdese-Himalaya orogens.(3)The basement of the Plateau is dominated by weakly magnetic Proterozoic metamorphic rocks and lacks strongly magnetic Archean crystalline basement of stable continents such as the Tarim and Sichuan blocks.Therefore,it exhibits the characteristics of unstable orogenic basement.(4)The Yarlung-Zangbo suture zone forming due to continent-continent collisions since the Cenozoic shows double aeromagnetic anomaly zones.Therefore,it can be inferred that the Yarlung-Zangbo suture zone formed from the Indian Plate subducting towards and colliding with the Eurasian Plate twice.(5)A huge negative aeromagnetic anomaly in nearly SN trending has been discovered in the middle part of the Plateau,indicating a giant deep thermal-tectonic zone.(6)A dual-layer magnetic structure has been revealed in the Plateau.It consists of shallow magnetic anomaly zones in nearly EW and NW trending and deep magnetic anomaly zones in nearly SN trending.They overlap vertically and cross horizontally,showing the flyover-type geological structure of the Plateau.(7)A group of NW-trending faults occur in eastern Tibet,which is intersected rather than connected by the nearly EW trending that develop in middle-west Tibet.(8)As for the central uplift zone that occurs through the Qiangtang Basin,its metamorphic basement tends to gradually descend from west to east,showing the form of steps.The Qiangtang Basin is divided into the northern and southern part by the central uplift zone in it.The basement in the Qiangtang Basin is deep in the north and west and shallow in the south and west.The basement in the northern Qiangtang Basin is deep and relatively stable and thus is more favorable for the generation and preservation of oil and gas.Up to now,19 favorable tectonic regions of oil and gas have been determined in the Qiangtang Basin.(9)A total of 21 prospecting areas of mineral resources have been delineated and thousands of ore-bearing(or mineralization)anomalies have been discovered.Additionally,the formation and uplift mechanism of the Plateau are briefly discussed in this paper.

石油微生物勘探技术在西柳地区的应用

将油气微生物勘探新技术应用于西柳地区进行采样 ,并进行了烃氧化菌培养 ,根据经验确定了本研究区的 2个微生物异常区 ,即中北异常区和东南异常区。与研究区内现有已钻的 12口井相比 ,其油气微生物勘探结果的符合率为 75 % ,效果是良好的。同时 ,通过油气微生物勘探技术实践 ,总结并讨论了该技术分析结果的客观性以及地表和断层的影响因素、导致部分结果不相符的原因 ,这对我国复杂地下地质条件的油气勘探具有指导意义。最后 ,在油气微生物勘探结论的基础上 ,结合圈闭、油源等条件对试验区进行了含油性预测 。

大庆卫星油田微生物勘探技术研究

将微生物勘探技术应用于大庆卫星油田油气成熟开发区,揭示了卫星油田工区内受断层控制的油气富集规律,将成熟开发区向西侧进行了拓展,且在未知区域发现了4个油气富集区。这4个油气富集区的总面积为16.08km2,占总研究区面积的19.7%,这表明研究区内的含油气远景不是十分理想。根据微生物异常区形态和面积、微生物异常最大值和平均值,将微生物异常区与断层的关系与已知含油气区进行了比较,对4个油气富集区进行了分级。其中:中部异常区为最有利的目标区块;其次是东南异常区。根据卫星油田油气微生物勘探结果,在工区内部署了10口评价控制井。钻井证实,其含油气性符合率达80%。这对于我国的复杂油气藏,特别是岩性油气藏的后期开发提供了一个新的技术支撑,将对我国的油气勘探尤其是在油田开发区寻找剩余油及扩边增储产生深远的影响。

地质微生物技术在油气勘探开发中的应用

总结了地质微生物技术包括油气微生物勘探技术(MPOG)和本源微生物采油技术(MEOR)的理论基础和原理,简述了MPOG和MEOR技术的流程和主要特点等,评述了MPOG和MEOR技术在石油天然气勘探开发中的应用现状。MPOG和MEOR技术的应用实践表明,加强基础理论研究,培养和造就一批拥有微生物学、生物化学、地球化学、石油地质学和石油工程学等多学科理论和技术的专门人才或者实现了这些相关学科人才的有效结合,发展中国自己的成套地质生物技术,必将对大幅度提高我国油气勘探成功率和采收率产生深远的影响。

二连盆地马尼特坳陷天然气微生物勘探

油气微生物勘探技术(MPOG)因具有直接、有效、多解性小和经济效益好等优势日益受到全球油气勘探界的重视。运用油气微生物勘探新技术中的天然气微生物勘探技术,在二连盆地马尼特坳陷进行了采样和甲烷氧化菌培养,之后根据经验确定了该坳陷的2个气异常显示区即西北异常区和中南异常区,发现该两异常区异常值与区内已钻井的勘探结果基本相符,说明微生物勘探技术效果较好。通过油气微生物勘探技术实践,讨论了该技术分析结果的客观性和地表、断层等因素对该技术效果的影响。认为该技术对我国复杂地质条件下的天然气勘探具有重要的应用价值。在天然气微生物勘探基础上,结合圈闭、油源等条件对研究区进行了含油性预测,并确定了最有利的布井点位。

生物法在油田地面处理及地下开采系统中的应用

概述了生物技术在油田地面处理和地下开采系统中的发展现状和存在的问题,重点论述了在地面和地下两个生产系统中的热点研究方向。在地面处理系统中,生物技术已经涉足到多个研究领域,尤以生物修复、生物破乳、生物絮凝3个方面得到了广泛研究和一定应用,但受到技术成熟度、实际工况条件、处理成本等因素的限制,制约了其进一步的推广和应用。在地下开采系统中,生物技术涉猎范围很小。其中,微生物驱油技术历经几十年的发展,业已成为油田系统最具深远意义的前沿热点研究领域,部分成果已经得到了小规模的应用,但该技术难以实现受控,且极大地受到油藏特点的影响,限制了其推广;此外,近年来发展起来的油藏勘探技术成为一大亮点,利用地表微生物群落构成识别油藏的位置已经取得了一定成果。未来随着相关技术不断完善,解决与实际工况条件有机契合问题,将促使生物技术在油田生产中有更为广阔的发展前景。