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1.
Six wells were drilled in the North Falkland Basin in 1998. Five of these wells recorded oil shows, and up to 32% gas was also recorded in mud returns to the rig floor. However, none of the wells encountered commercially viable petroleum accumulations.
The syn-rift and early post-rift intervals contain thick, lacustrine claystones with oil source potential as indicated by TOC values up to 7.5% and Rock-Eva1 S2 values of up to 102 kg HC per tonne of rock. These source rocks were immature or only marginally mature in five of the wells but had attained maturity in one of them. Modelling suggests that the main source interval may well be within the peak oil generation window in deeper, undrilled parts of the basin. Calculations of the amount of oil expelled range up to 60 billion barrels.
Most of the wells tested a closely-related set of plays in large structures asSociated with a sandstone interval near the top of the late syn-rifi to early post-rij? source-rock succession. Post-drilling geological modelling of the basin suggests that oil is unlikely to have migrated into this sandstone play at the localities tested, and that the wells consequently failed largely due to a lack of charge. Howevel; the play maintains exploration potential elsewhere. Other plays, particularly those stratigraphically asSociated with the base rather than the top of the source rock, may have a higher chance of exploration success.  相似文献   

2.
This study reports aqueous solubilities of crude oil distillation fractions over the carbon number range C1- C 34 as a function of: temperature (100° to 400° C), pressure (100 to 2,000 bars), NaCl concentration, and gas in solution (N 2, CO 2, CH 4). Experimental parameters were designed so that conditions within a petroleum basin would be duplicated. Increases in temperature increased crude oil solubility, and the higher molecular weight species were affected more positively than lower molecular weight species. Increases in pressure or salinity decreased solubility. The presence of gas in solution increased the solubility of high molecular weight hydrocarbons (> C 24) over all temperatures, and increased the solubility of lower molecular weight hydrocarbons at high temperatures (> 180–260°C). Gas decreased the solubility of low molecular weight hydrocarbons at low temperatures.
Hydrocarbon solute compositional changes were also examined as a function of the above parameters. At high temperatures, both increasing gas concentration and increasing temperature caused hydrocarbon solutes to become compositionally more similar and eventually identical to the original distillation fraction. The high molecular weight hydrocarbons and saturated hydrocarbons, especially the n-paraffins, were taken into solution in progressively greater concentrations over the aromatic and low molecular weight hydrocarbons. Thus, the strong preferential uptake of low molecular weight and aromatic hydrocarbons into solution at lower temperatures was reversed.  相似文献   

3.
The injection of steam into oil reservoirs is a technique commonly used for improving the production of heavy crude oils. Very often, a change in the composition of the oil and gas produced may be observed during steam flooding. In general, corrosive gases, such as H2S and CO2, are produced in increased quantities.
In laboratory experiments on sulphur-bearing reservoir minerals and crude oils the origin of the change in oil and gas composition was investigated. Temperatures up to 370°C were applied to study temperature- and rate-dependent phenomena. By means of X-ray fluorescence, gas chromatography and chemical precipitation methods, the change in the sulphur material balance was studied.
It was shown that gas evolution depends strongly on the temperature of the steam injected. Furthermore, it was possible to prove that the gases evolved during steam flooding (such as CO2, H2S etc.) originate from the decomposition of crude oil components. Besides these investigations, a drastic viscosity increase of the residual crude oil was observed after steam injection was applied.
It is concluded that the production of H2S and CO2 may be controlled by temperature adjustment of the steam being injected.  相似文献   

4.
Based on natural data-sets and several hydrous-pyrolysis experiments on immature humic coals, the conventional "oil window" (0.5–0.6%R0 to 1.3–1.35%R0) for humic coals is re-considered. A worldwide coal data-set comprising coals of Carboniferous - Tertiary age and having vitrinite reflectances from 0.32%R0 to 3.6%R0 indicates that initial liquid hydrocarbon generation commences at a vitrinite reflectance of 0.5%R0 to 0.6%R0, and that a significant liquid hydrocarbon build-up occurs from approximately 0.6%R0 to 0.85%R0. The start of the "oil window" corresponds to a vitrinite reflectance of 0.85%R0; however, the start of the "oil window" can vary significantly for individual coal series, and it may range up to a vitrinite reflectance of 1.15%R0. Liquid hydrocarbon generation is negligible at a vitrinite reflectance of approximately 1.8%R0, and at 2.0%R0 the hydrocarbon generative potential is exhausted. A vitrinite reflectance of 1.8%R0 corresponds to the end of the "oil window", and for general use a vitrinite reflectance range of 0.85–1.8%R0 is suggested to define the "oil window" for humic coals and kerogen type III. The end of the "oil window" at 1.8%R0 is supported by published data, indicating a much higher thermal stability of nC15+ hydrocarbons than is generally accepted, and therefore limited oil-to-gas cracking at 1.3%R0. The re-considered "oil window" between 0.85–1.8%R0 has significant implications for evaluating the prospectivity of basins dominated by terrestrial organic matter, such as coals.  相似文献   

5.
三肇凹陷扶杨油层源断裂的再认识及其对成藏的控制作用   总被引:2,自引:0,他引:2  
付广  王有功  袁大伟 《石油学报》2010,31(5):762-766
对三肇凹陷青一段源岩生成的油向下伏扶杨油层"倒灌"运移通道类型及分布特征研究表明,三肇凹陷扶杨油层源断裂不是过去认为的从青一段底(T2)断至嫩三段底的断裂,而应为上部消失于青一段源岩中的T2断裂。这些断裂主要为坳陷期活动的断裂和断陷期形成、坳陷期继续活动的断裂,在整个凹陷分布广泛。三肇凹陷青一段源岩生成的油向下"倒灌"运移距离主要受青一段源岩古超压值与油"倒灌"运移阻力差的控制,同时还受到被T2源断裂错断的扶杨油层砂泥组合关系的影响。青一段源岩生成的油向下"倒灌"运移的实际距离可达到300m,高值区主要分布在油田区域内。T2源断裂对油成藏与分布的控制作用表现在:T2源断裂发育区控制油聚集区域;T2源断裂发育程度控制着油"倒灌"运移的距离;T2源断裂附近高断块圈闭有利于油聚集成藏;距T2源断裂的距离控制着油井产能。  相似文献   

6.
The hydrocarbon compositions (C1/ΣC1—C4) = 0.96-0.98) and the carbon isotopes ratios of methane (—51.4 to—52.1%) studied in the Zohar Gas Field indicate that the generations of the gas was associated with an oil-generation process. Thus, gas and heavy oils found in the area could have formed simultaneously within one system.
The carbon isotope composition of the CO2 is relatively heavy, with δ13 CO2 value ofabout +7% which is probably the original value of the CO2 generated by biodegradation of the cruded oil.
The dissimilarity in the organochemical characteristics of the Kidod shales, which cap the gas reservoirs and the oils found in the region, as well as the low degree of maturation of the Kidod, shales, negate the accepted hypothesis that these shales are the source rock of the heavy oils and the gas found in the Zohar area. The vitrinite reflectance of the reservoir rocks and of the underlying Jurassic sequences, which is only 0.5%, infers that the gas is not trapped near its site of generation.  相似文献   

7.
柴达木盆地北缘块断带原油的地化特征及油源问题   总被引:2,自引:2,他引:0       下载免费PDF全文
柴达木盆地北缘断层纵横交错,控制着本区的构造格局和中新生界地层的岩性和厚度,故称北缘块断带。其范围西起昆特依凹陷,东至旺尕秀地区,北界阿尔金山—祁连山山前断裂带,南邻葫芦山、埃姆尼克山一线,面积约三万平方公里(图1)。   相似文献   

8.
Accurate estimates of losses occurring during secondary petroleum migration are of vital importance for valid petroleum systems assessments. In this paper, we discuss the development of migration pathways and the corresponding hydrocarbon losses using data from laboratory experiments based on diphasic immiscible draining processes. These experiments permitted us to study the formation of migration pathways, the distribution of non-wetting oil along these pathways, and the re-utilization of existing pathways by later pulses of migrating oil.
The configuration of a migration pathway can be characterized by a phase diagram whose coordinates are two dimensionless numbers: the capillary number and the Bond number (a measure of the buoyancy force). NMR imaging was used to measure the saturation of residual oil within the pathways. It was found that, after migration, the average residual oil saturation within a pathway was generally less than 40% at a resolution of 0.4mm. Hydrocarbon losses during migration were estimated as the product of the volumetric proportion of the migrating cluster structure, defined using this spatial resolution, multiplied by the average residual oil saturation in the pathway.  相似文献   

9.
Cuttings samples from eight wells in the Muglad Basin have been analysed using a combination of organic geochemistry and palynofacies. The lacustrine Aptian-Albian shales of the Abu Gabra Formation, previously identified as the main source rock, have an overall mean TOC of 1.43% (n = 146), with those from the NW part of the basin (Sharaf area) being approximately twice as organic-rich as those from the SE (Heglig area). The Abu Gabra Formation contains two distinct organic facies: a lower interval dominated by higher TOC values (1.5–2.3%), higher measured hydrogen indices (338–546), higher amorphous kerogen contents (>80%), and heavier δ13CTOC values (> −27%0); and an upper, less rich interval (mean TOC 1.4%, mean HI 83, δ13CTOC approximately −28%0). The isotopic contrast between the upper and lower units may potentially be of stratigraphic use. The organic facies differences appear to reflect deteriorating preservation of the organic matter (higher dissolved oxygen, possibly due to shallower conditions resulting from lower rates of subsidence). Use of S2 v. TOC plots suggests corrected true mean hydrogen indices of around 800 in the richer facies (corresponding to a Type I kerogen). Mean random vitrinite reflectance, pyrolysis Tmax values, and visually determined fluorescence colours indicate that the samples studied are mostly immature, or at most in the earliest part of the oil window (<0.7% VRo); biomarker data suggest that the vitrinite reflectance values may be suppressed by up to 20%.  相似文献   

10.
秦岭—大别造山带北侧盆地序列及油气前景   总被引:1,自引:1,他引:0       下载免费PDF全文
秦岭—大别造山带北侧存在多个盆地,其中有些盆地中已有一定的油气显示。近年来地质、地球化学研究成果表明,秦岭—大别造山带北侧主要发育6个世代的盆地序列,分别是:1)被动大陆边缘盆地(-C1—O2);2)弧后盆地(O2—C1);3)残余盆地(C2—T2),其中可分为残余盆地第1阶段(C2—P12)和残余盆地第2阶段(P12—T2);4)陆内前陆盆地(T3—J);5)张扭性盆地(J3—K1);6)断—拗盆地(K2—E)。秦岭—大别造山带北侧盆地发育6套烃源岩层系,分别是古近系、下白垩统、下侏罗统、上三叠统、石炭—二叠系和下古生界,并进行了相关烃源岩层系的成藏特征分析。东秦岭—大别山北侧主要勘探层系第一位的是石炭—二叠系,第二位是下白垩统,第三位是上三叠统,第四位是古近系,而中—下侏罗统及下古生界可列为第五位。建议勘探选区是一类盆地为周口盆地、济源盆地和洛—伊盆地。有利区带是谭庄—沈丘凹陷、倪丘集凹陷、襄城凹陷、舞阳凹陷、孟县—温县凹陷和洛阳凹陷。   相似文献   

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