Jungang Lu

The influence of bitumen on reservoir properties and hydrocarbon accumulation in the Santai Area of the Junggar Basin, North Western China

ABSTRACT Bitumens influence on reservoir properties and hydrocarbon accumulation in Santai area was studied by experiment measures and geochemical evidences. The porosity and permeability of the sandstones containing bitumen increased significantly by dissolving experiments, implying that bitumen strongly influences the reservoir properties. The analysis reveals that there were two stages of hydrocarbon accumulation. In the first stage oil migrated into coarse-grained sandstone and then degraded to bitumen, which deteriorated the reservoir properties. The second stage oil had to migrate into fine-grained sandstones, or the residual pores of the bitumen-containing coarse-grained sandstone. Exploration in this area should avoid the bitumen distribution zone.

Geochemical characteristic and origin of solid bitumen in the Jurassic and Triassic sandstone reservoir of Santai Area, Junggar Basin, NW China

ABSTRACT Solid bitumen was identified in the pore spaces of the Jurassic and Triassic sandstone reservoir in the Santai Area, Junggar Basin, NW China, which limits economic petroleum production, even influencing hydrocarbon accumulation. Organic geochemical techniques were figured out the origin of bitumen and its formation mechanisms. Carbon isotope characteristics of the crude oil and bitumen-reservoir extracts suggests the bitumen mainly derived from sapropelic-type source rock of Pingdiquan Formation, which was deposited in the semideep and deep lacustrine environment. Biomarker date indicates bitumen was formed from petroleum in low thermally mature stage and biodegradation was responsible for formation of the bitumen.

NMR method to calculate the bitumen saturation in the deposit

ABSTRACT Deposit bitumen is a highly viscous, asphaltene-rich hydrocarbon that can fill in the pores as the cement reduce the porosity in the deposit. The authors comparatively analyzed the experimental data of the nuclear magnetic resonance before and after the dissolving of bitumen-rich core samples. The short transverse relaxation times (T2) and consequently lower NMR porosity are characteristics of bitumen-rich zones. An NMR method was used to reconcile core data as well as to calculate the saturation of bitumen in the deposit.

The influence of water on the thermal simulation experiment of hydrocarbon generation and expulsion

ABSTRACT Thermal simulation experiment of hydrocarbon generation and expulsion is an important method for the study of source rock evolution. The role played by water in organic material evolution was clarified by summarizing the effect of water on different pyrolysis systems. According to the results, the hydrous experiment has a better hydrocarbon generation rate than the anhydrous experiment in the closed system. In the semi-open system, high-pressure water vapor has good effect to gas generation, while near-critical water (NCW) improves the oil and total hydrocarbon productive rate. So, it is inferred that NCW improves the conversion of kerogen to hydrocarbon reactions, and increases the dissolving capacity of hydrocarbons.

Overpressure water zone influence on hydrocarbon migration and oil reservoir distribution in low Cretaceous formations of Yinger sag, China

ABSTRACT The low Cretaceous Zhonggou, Xiagou, and Chijinpu formations are major source rocks in Yinger sag, Jiudong Basin, China. Oil reservoirs were discovered in Zhonggou and Chijinpu formation, which were on the top and bottom of overpressure water zone, but no hydrocarbon was discovered within overpressure zone. The impact of overpressure zone on oil accumulation was indicated by reservoir fluorescence and oil-source correlation study through geochemical analysis. The result shows the overpressure zone reservoirs have less fluorescence display and reservoir extracts dissimilar to source rocks of Chijinpu or Zhonggou formation, implying the inexistence of oil migration in overpressure zone.

The source of cretaceous oil and gas in Dinan bulge, Junggar Basin

ABSTRACT The analysis on natural gas, light hydrocarbons and biomarkers, and comparison with periphery structures by the whole hydrocarbon geochemistry has been made to figure out controversial Dinan Cretaceous source. The oil, similar to Dongdao-3 reservoir extracts but different from Kelameili oil, is characterized by light carbon isotope, small light-hydrocarbon value, high methyl cyclohexane but low C28 sterane abundance, while natural gas differs in components and carbon isotopes from typical Carboniferous gas. Moreover, both Dinan Cretaceous oil and gas are sourced from Dongdaohaizi sag where crude oil is generated from Permian and Jurassic maturation while gas is from Carboniferous high-over maturation and Permian maturation.

The source of gas and oil in Cainan oilfield Jurassic layers of Junggar Basin

ABSTRACT The aim of this paper is to analyze natural gas, light hydrocarbons, and biomarkers by the whole hydrocarbon geochemistry to figure out controversial source of Cainan oilfield. Dry gas and oil reservoirs in Baijiahai suggest multi-stage accumulation of mature and high-over mature gas from widely distributed methane carbon isotope and humic, which are products of heavy ethane carbon isotope. The natural gas in Fubei slope area is typical mature wet gas. According to regional structural and evolution features, high-over mature gas in Baijiahai originates from Carboniferous source rocks of Dongdaohaizi sag, while mature crude oil is a mixture of Jurassic and Pingdiquan formation of Permian.

Comparison on geochemical characteristics between oil shale and black mudstone of Yanchang formation Chang 7 in the Erdos Basin, China

ABSTRACT Geochemical characteristics between high quality oil shale and black mudstone of Chang 7, Yanchang formation of Erdos Basin were compared through certain analyses on sedimentary environment and parent materials of different source rocks combined with comprehensive evaluation of source rocks and parameter analysis of biomarkers. The results showed the oil shale formed from deep-lacustrine reducing environment, but the black mudstone formed from semi-deep-lacustrine weak oxidation environment. In addition, oil shale has better total organic carbon, hydrocarbon potential and organic types while black mudstone has better abundance of 17α(H)-diahopanes and Ts.

Application of 17α(H)-diahopanes in oil-source correlation of Triassic Yanchang formation in Zhoujiawan area, Ordos Basin, China

ABSTRACT 17α(H)-diahopane are extensively distributed in Yanchang formation source rocks of Ordos Basin, but the content varies greatly. The content of 17α(H)-diahopane is pretty low in Chang 7 oil shale, whereas it is very high in Chang 9 mudstones. Low diahopane abundance of Chang 81 reservoir extracts and similar crossplots of Ts/C29Ts and C30 diahopane/C30 hopane show that Chang 81 oils come from Chang 7 oil shale. However, Chang 82 and Chang 9 reservoir extracts are similar to Chang 9 source rocks in most of geochemical parameters, which indicates that the oil is derived from Chang 9 source rocks.

The characteristics and accumulation conditions of tight oil in the Huoshaoshan area, eastern Junggar basin, northwest China

ABSTRACT Source rock and oil geochemistry and reservoir physical property research were employed to study the characteristics and accumulation conditions of tight oil in Huoshaoshan area. The result indicated the maturity and physical properties of oil were varied in different well blocks though the source rocks were in similar maturity stage, the reservoir physical property was key factor to cause the diversities of oil characteristics. The tight reservoir is almost filled with low-mature oil derived from native source rocks, the relatively good reservoir not only accumulates local low-mature oil, but also reserve lots of mature oil from other source rocks.