Formation of oil and gas fields

Cycles of the geosynclinal-orogenic-platformal development of the continental crust are separated by natural phases of crustal destruction. They are determined by pulses of degassing of the Earth’s core marked by decelerated inversions of the magnetic field. Such pulses occur under the influence of fluid flows that ascend from the core and loss hydrogen. Consequently, the fluids acquire acidic properties and become aggressive to rocks of the continental crust (H₂ + 2CO = H₂ O + 0.5CO₂ + 1.5C). Oceanization of the continental crust represents the main result of its destruction accompanied by the formation of seas and sedimentary basins largely on the underwater margins of continents. Development of geodynamic compression setting of the Earth’s crust due to its evolution creates conditions that impede the loss of hydrogen from ascending fluid flows. Consequently, they acquire the ability to generate hydrocarbons (4H₂ + 2CO = 2H₂O + CH₄ + C) and produce oil and gas pools. This setting is marked by intrusions of alkaline rocks with characteristic water-hydrocarbon inclusions in minerals and by the development of fold-thrust and reversed fault dislocations in depressions. The dislocations controlled not only the fluid-related leaching of rocks, but also the distribution of oil and gas pools within both sedimentary basins and their basement.     

渤海湾盆地渤中19-6凝析气田凝析油成熟度判定及成因意义

关于渤海湾盆地渤中19- 6凝析气田凝析油成熟度存在成熟与高成熟两种截然不同观点,尚未达到统一定论。本文综合利用轻烃、饱和烃和芳烃成熟度参数对凝析油成熟度进行了综合判定,并深入分析了凝析油和天然气的成因关系及凝析气藏形成机制。结果表明：异庚烷值与庚烷值、Ts/（Ts+Tm）与C29Ts/（C29Ts+C29H）、甲基单金刚烷指数与甲基双金刚烷指数、甲基菲指数、二苯并噻吩类成熟度参数和TNR2显示渤中19- 6凝析气田凝析油处于成熟阶段。结合天然气成熟度和储层流体包裹体特征,可知渤中19- 6凝析气田的原油成藏期早于天然气,随着晚期大量天然气的充注,油气会发生相控混溶作用形成含液态烃的气流体,当温度和压力达到混溶后烃类体系的露点以上,则形成凝析气藏。     

Physicochemical peculiarities of absorbed oil in core samples of gas condensate deposit

The problem of the composition of absorption hydrocarbons and liquid condensate arises in the study of gas condensate reservoirs. From the examples of the gas condensate part of the Karachaganak, Astrakhan, and Yamburg deposits, it is shown that absorption hydrocarbons (absorption oil) contain polar components with S and O atoms in molecules. The differences in the physicochemical properties of absorbed oil and precipitated liquid condensate are revealed, as are the regularities in the composition and properties of the absorbed oil and condensate. The criteria for division of absorption oil and liquid condensate are given.     

Gravity monitoring at oil and gas fields: data inversion and errors

The present paper considers certain problems of gravity monitoring at oil and gas fields arising due to inversion of repeat measurement data, when finding the positions of water-oil and water-gas contacts. The main sources of noise in gravity data are errors in vertical positioning of the tool, changes in atmospheric pressure, and variations in groundwater level and soil moisture. An algorithm based on using a multisensor borehole tool is proposed for a more accurate inversion. Examples of locating successfully the water front while solving model problems with the help of this algorithm are provided.     

X-ray tomography in petrophysical studies of core samples from oil and gas fields

The porosity and permeability of core rocks were studied by X-ray tomography. This method has a high potential for studying petrophysical properties of rocks, because it permits not only a general quantitative estimation of the void volume but also visualization of the rock texture, including pores, cavities, cracks, and zones of different densities in the matrix. X-ray tomography permits detailed studies of rock inhomogeneity, which are necessary for the elaboration of reliable porosity-permeability models for hydrocarbon pools. The investigations at Perm State National Research Polytechnic University have shown that X-ray tomography of core samples has a wide spectrum of applications in petroleum geology. Nikon Metrology XT H 225 X-ray computed tomography makes it possible to examine samples with a standard diameter (30 mm) and whole core samples (100 mm). The structure of voids in carbonate and terrigenous rocks was studied on samples with standard and full diameters; the results of hydrochloric acid treatment of carbonate reservoir rocks were visualized; and the mechanical properties of rock salts were studied. Three-dimensional models for the structure of voids and mineral matrix of the core samples have been constructed with the use of the Avizo Fire software.     

呼图壁凝析气田构造控藏过程讨论

呼图壁气田是新疆准噶尔盆地南缘中段发现的第一个中型凝析气田。文章从区域构造应力特征及构造运动方式入手,重建了呼图壁背斜构造演化历史,综合分析了呼图壁气田成藏过程和成藏的关键控制因素。结果表明,呼图壁背斜构造形成演化,受幕式挤压应力、沉积压实作用及滑脱层的共同控制。同时,晚新生代的区域强烈SN向挤压应力不仅使得中下侏罗统煤系烃源岩迅速达到高-过成熟阶段并大量生气,而且造成地层异常高压以及断裂的开启,进而为呼图壁气田的形成提供气源和通道。而SN向水平区域构造挤压应力、异常高压及断裂是呼图壁气田成藏的主控因素。此认识对于呼图壁气田的开发、利用,以及在准噶尔盆地南缘寻找新的天然气勘探耙区,都具有指导意义。     

Influence of deep gas-steam fluids on the composition of reservoir waters of oil and gas fields

In this work the conditions of the formation of low-mineral deep hydrocarbonate sodium waters of oil-and-gas fields are considered. Analysis of the boron-bromine ratio of reservoir and condensed waters in several fields of Western Siberia shows that the influx of endogenous high-temperature gas-steam fluids into zones containing sedimentogenic brines is a decisive factor in the formation of the chemical composition of deep waters that are low in minerals.     

Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields

The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a J-shape, and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment.This paper was presented at Emerging Concepts, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.     

油气田地区土壤-水环境中有机污染的数值模拟及模型预测

针对油气田地区的地下水污染日益突出问题，文章综合考虑石油类有机污染物在包气带中扩散、吸附解吸、分配和生物降解等环境行为，建立了土壤－水环境体系有机污染物迁移转化的非平衡动力学模型，并编制了RBCA有限元程序，预测污染物在土壤－水环境中浓度分布变化趋势，探讨了模拟参数κd、κ变化对有机污染物迁移的影响。模拟结果表明：吸附解吸速率参数的变化对污染物达到平衡状态起着决定性作用，其结果可为定量研究有机污染物在土壤－水环境中的归宿提供可靠的理论根据，同时为油气田勘探开发过程中的污染控制与治理措施提供依据和理论指导。     

雅克拉白垩系凝析气藏气油比变化趋势分析

1998年至2000年，YK1井生产气油比出现连续下降趋势。经分析，初步认为这是由于凝析气藏不同部位的凝析气性质不同造成的。1 生产简史和存在问题 雅克拉凝析气藏于1984年SC2井井喷发现，后又连续钻探了S4、S5、S6、S7、S15等井，探明了奥陶系和白垩系两个主要凝析气藏。SC2井试采奥陶系，后出于安全考虑停产；S7、S15试采白垩系，其中S15井1994年发生井口失控事故停产。YK1是S15的替身井，布井时向东移至构造高部位，于1996年投产白垩系下气组。截止2000年10月，储量采出率为4.48%。据储量报告，上、下气组具有统一气水界面和同一压…     

Relationship between crude-oil properties and geology in some oil and gas fields in the Niigata basin,Japan

The crude oil separately sampled from every producing well in the two fields in the Niigata Neogene sedimentary basin was analysed chemically and tested physically. The data obtained were interpreted, taking the geological conditions of the reservoir fully into consideration.     

全球大型凝析气田的分布特征及其形成主控因素

随着勘探的不断深入,越来越多的凝析气藏被发现,并受到重视。目前全球共发现106个大型凝析气田,分布于全球70多个沉积盆地。凝析气田主要分布于西西伯利亚盆地、滨里海盆地、波斯湾盆地、扎格罗斯盆地、美国墨西哥湾及塔里木盆地等。通过对全球各大凝析气田进行系统的研究,发现凝析气藏主要分布在石炭系—新近系储层中,以构造圈闭为主,储集体物性较差,属于低孔低渗型,凝析气和凝析油的密度均相对较低。凝析气田的形成和展布主要受控于有效烃源岩分布、有利的储盖组合、圈闭类型、晚期成藏、特殊的温压系统和烃类体系组分等条件。根据其成因机理,将凝析气藏分为原生凝析气藏和次生凝析气藏。     

世界碳酸盐岩油气田的储层特征及其成藏的主要控制因素

世界碳酸盐岩储层的类型可识别为6种类型:不整合面之下的储层、白云岩储层、鲕粒和团粒浅滩储层、生物礁储层、微孔隙储层以及微裂缝储层。尚有深埋溶解型储层,但此类较少。上述各类储层,如出露水面,遭受雨水淋滤,必将增加其孔隙度,成为重要的油气储层。中东地区碳酸盐岩之所以能形成世界级的大油气田,其基本要素为油气的生储盖层组合的密切配置、有台地内继承性发育的生油盆地、含油气层的年代较新,且石油进入构造圈闭的时间也较晚、构造圈闭规模巨大、有十分理想的区域性的盖层。正是这些要素的有机配合,从而形成世界上无可匹敌的大油田。对中国碳酸盐岩油气田的储层研究,应寻找上述这些原生储层,又经历次生溶蚀和白云石化作用,这样才能成为有效的油气储层。     

Bromine as an indicator of oil migration in northern Iraqi oil fields

The Br content of oil varies systematically along the paths of oil migration in northern Iraqi oil fields, indicating that this element may be used as an indicator of oil movement. The variation in Br parallels that of V and Ni, and like these two elements it is concentrated in the asphaltene fraction of petroleum.     

中国东部陆相断陷盆地成熟探区油气勘探新领域分析*

经过50多年勘探开发,中国东部陆相油气田均已进入勘探中后期阶段,受石油地质认识局限性和勘探技术的限制,待发现目标日趋隐蔽,油气勘探难度日益增大。针对中国东部陆相断陷盆地深层低孔渗—致密砂岩储集层评价方法的局限性、深部砂砾岩储集体成因模式问题以及基岩风化壳形成和分布的复杂性问题,作者经过近几年的探索和总结,取得以下主要研究进展: (1)基于砂岩储集层物性演化动力学原理,提出了致密砂岩储集层动态评价的新思路和新方法,指出过去评价较低的深部凹陷带低孔渗—致密砂岩体仍然具有较大的勘探潜力; (2)运用地震地层学方法,通过建立断陷盆地陡坡带斜向大型扇三角洲沉积模式,指出斜向大型扇三角洲砂砾岩是断陷盆地深层有利的储集体,可以作为下一步有利勘探方向; (3)根据基岩风化壳双层结构新模式,结合风化壳储集层改造—破坏—保存机理的动力学新模型,指出断陷盆地中低部位是最有利风化壳储集层发育带,断陷盆地缓坡内带(洼槽区)风化壳是下一步油气勘探的重要新领域。文中提出的上述3大勘探新领域不仅是对断陷盆地油气成藏模式的补充和发展,更重要的是展现出中国东部断陷盆地深层常规和非常规油气勘探领域的巨大潜力,为深化东部成熟盆地油气勘探指出了明确的方向。     

中国东部陆相断陷盆地成熟探区油气勘探新领域分析*

经过50多年勘探开发,中国东部陆相油气田均已进入勘探中后期阶段,受石油地质认识局限性和勘探技术的限制,待发现目标日趋隐蔽,油气勘探难度日益增大。针对中国东部陆相断陷盆地深层低孔渗—致密砂岩储集层评价方法的局限性、深部砂砾岩储集体成因模式问题以及基岩风化壳形成和分布的复杂性问题,作者经过近几年的探索和总结,取得以下主要研究进展: (1)基于砂岩储集层物性演化动力学原理,提出了致密砂岩储集层动态评价的新思路和新方法,指出过去评价较低的深部凹陷带低孔渗—致密砂岩体仍然具有较大的勘探潜力; (2)运用地震地层学方法,通过建立断陷盆地陡坡带斜向大型扇三角洲沉积模式,指出斜向大型扇三角洲砂砾岩是断陷盆地深层有利的储集体,可以作为下一步有利勘探方向; (3)根据基岩风化壳双层结构新模式,结合风化壳储集层改造—破坏—保存机理的动力学新模型,指出断陷盆地中低部位是最有利风化壳储集层发育带,断陷盆地缓坡内带(洼槽区)风化壳是下一步油气勘探的重要新领域。文中提出的上述3大勘探新领域不仅是对断陷盆地油气成藏模式的补充和发展,更重要的是展现出中国东部断陷盆地深层常规和非常规油气勘探领域的巨大潜力,为深化东部成熟盆地油气勘探指出了明确的方向。