Petroleum reservoir

About: Petroleum reservoir is a research topic. Over the lifetime, 5403 publications have been published within this topic receiving 83535 citations. The topic is also known as: petroleum deposit.

Exploration Potential and Geological Conditions of Tight Oil in the Qaidam Basin

Abstract: There are geological conditions for the formation of tight oil in the Qaidam basin.The Middle and Lower Jurrasic semi-deep lacustrine facies mudstone and the Tertiary semi-deep lake facies to deep lake facies mudstone are widely distributed in the Qaidam basin,which constitutes a favorable relationship of source and reservoir coexistence for the formation of tight oil with bank to shallow lake facies sand body or carbonate rock which is interbeded with or situated near the source rocks.The Jurassic source rocks in the northern margin of the Qaidam basin have an average organic carbon value of 1.85,Ⅰ-Ⅱ2 organic types and a maturity range from mature stage to over mature stage with better oil generation potential.The Tertiary source rocks in the west of the Qaidam basin have a range of organic carbon from 0.4%to 1.2%,Ⅰ-Ⅱ1 organic types and a Ro value from 0.4% to 1.2% within an oil generation window.Compared to other Chinese basins,the degree of hydrocarbon inversion of the Tertiary source rocks is high.The clastic reservoir space is dominated by remained intergranular pores and corroded pores with porosity from 3.8% to 10.2% and permeability from 0.1×10-3μm2 to 2×10-3μm2.The reservoir rocks have characteristics of thinner single beds,vertical multilayer's superimposition,thicker accumulated thickness and many horizontal oil beds overlayed.The reservoir space of the carbonate rock is predominated by corroded pores and interbeded contracted cracks with porosity from 5% to 7% and permeability from 0.2×10-3μm2 to 0.7 ×10-3μm2.The reservoir rock is characterized by more single beds,thinner single beds,more sedimentary facies controlled and horizontal widely continuous oil beds.The groups of oil reservoir formation include four types,that is,inner source included group,upper source widely distributed model,lower source layered group,and beside source covered group,which are mainly controlled by source depressions.The tight oil in the Qaidam basin is enriched and has a great potential,being estimated the resource yield ranges from 8.16 to 10.46×108 Tons.After the analysis of reservoir forming conditions,we think that four favorable exploration areas,i.e.,Zhahaquan-Wunan,Xiaoliangshan-Nanyishan and Qigequan-Yaojin in the western Qaidam basin and Lenghu in the northern Qaidam basin,can be served as current exploration targets.

Dynamics for multistage pool formation of Lunnan low uplift in Tarim Basin

Abstract: Lunnan area in the Tarim Basin has become an important onshore oil production base in China. Formation of the oil and gas pools in the low uplift of Lunnan has experienced a comparatively complex process of dynamics. Based on the hydrocarbon generation period of source rocks, the formation period of cap rocks and traps, the analysis of organic inclusion and the analysis of bitumen in the reservoir, this paper draws the conclusion that the low uplift area of Lunnan has experienced three pool formation periods: the Permian period, the Cretaceous-Early Tertiary period and the Late Tertiary-Quaternary period and two oil and gas reservoir adjustment periods: the Late Permian period and the Late Tertiary-Quaternary period. The comprehensive study indicates that the largescale Ordovician buried hill, formed in Early Hercynian, became the reservoir during the Permian period, because the Cambrian-Lower Ordovician oil was discharged laterally into the reservoir along the top of the Ordovician weathering crust from south to north. The reservoir experienced a complicated process—reconstruction in the end of Permian, adjustment in Cretaceous-Early Tertiary and redischarging process in Late Tertiary-Quaternary, leading to the early original heavy oil reservoir of marine facies and the late original light oil reservoir and gas pool. Carboniferous, Triassic and Jurassic oil and gas reservoirs result from upward adjustment and redistribution of Ordovician oil and gas reservoirs. Of those results, the formation of Triassic-Jurassic oil and gas pools came under the influence of the northwardtilting structure. The oil and gas sourcing from the different hydrocarbon source rock intervals vertically migrated into the base unconformity of Triassic system. Then the oil and gas migrated laterally from north to south and accumulated into the reservoir.

Stress–strain analysis in productive gas/oil reservoirs

Abstract: A numerical study of the stress–strain distribution in a thin disc-shaped reservoir embedded in a poro-elastic half-space and subject to a unit pore pressure decline is presented. The results are then compared with those of a geometrically equivalent porous cylindrical body which is either free to or prevented from expanding laterally (oedometric analogy). The analysis is based on the linear theory of poro-elasticity solved with the aid of the finite element method. The strength source is provided by the pressure gradient generated in a small region surrounding the gas/oil field where pore pressure dissipates. The influence of the burial depth c is also investigated. The results show that the reservoir rock undergoes a vertical compaction δ which is independent of c and very close to the compaction of the equivalent confined cylinder. The confinement factor is also similar. The horizontal displacement is, however, much larger. Its maximum value occurs at the boundary of the field and is of the same order of magnitude as δ. In addition, at the outer reservoir margin shear stresses develop which are totally missing in both the free and the constrained cylinders. It is shown that the vertical displacements of reservoir top and bottom, as well as the radial ones, are sensitive to c, especially in shallow formations. Finally, the largest shear stress is found to be related to the magnitude of the pressure gradient, i.e. to the radial size of the neighbouring volume where pore pressure vanishes. Copyright © 1999 John Wiley & Sons, Ltd.

Diffusion of Light Hydrocarbons in Subsurface Sedimentary Rocks

Abstract: In a deep core hole penetrating Paleocene-age strata on Spitsbergen Island, diffusive transport of light hydrocarbons from a siltstone into an adjacent sandstone unit is strongly supported by regular patterns of concentration changes which are controlled by molecular type, size, and structure. Individual molecular species are ranked in sequence of increasing effective diffusion coefficients. Benzene and toluene appear to have anomalously high transportation rates. These observations are significant with respect to an evaluation of the role of diffusion processes for hydrocarbon migration.