Major controlling factors and hydrocarbon accumulation models of large-scale lithologic reservoirs in shallow strata around the Bozhong sag,Bohai Bay Basin,China

Based on the practice of oil and gas exploration and the analysis of shallow lithologic reservoirs,combined with the allocation relationship and enrichment law of oil and gas accumulation factors,main controlling factors and models of hydrocarbon accumulation of large lithologic reservoirs in shallow strata around the Bozhong sag are summarized,and favorable exploration areas are proposed.The coupling of the four factors of“ridge-fault-sand-zone”is crucial for the hydrocarbon enrichment in the shallow lithologic reservoirs.The convergence intensity of deep convergence ridges is the basis for shallow oil and gas enrichment,the activity intensity of large fault cutting ridges and the thickness of cap rocks control the vertical migration ability of oil and gas,the coupling degree of large sand bodies and fault cutting ridges control large-scale oil and gas filling,the fault sealing ability of structural stress concentration zones affects the enrichment degree of lithologic oil and gas reservoirs.Three enrichment models including uplift convergence type,steep slope sand convergence type and depression uplift convergence type are established through the case study of lithologic reservoirs in shallow strata around the Bozhong sag.

Prolific Oil and Gas Reservoirs Discovered in Extremely Shallow Sea in Dagang

ProlificoilandgasflowswereobtainedfromWellGangshen78intheextremelyshallowseaareaonNovember22.Adailyoilproductionof542.58m3andadailygasproductionof90500m3wererecordedona12.7mmchoke.ItisreportedthattheproducingformationinWellGangshen78doesnotbelongtoth...

The Anatomy of Shallow Water Sandy Braided River Reservoir Architecture

1 Introduction Reservoir architecture refers to pattern,scale,direction and overlapping relationship of different levels of architecture units.The research of architecture in fluvial phase began in the 1980s(Miall,1985).The braided river

Seismic Acquisition Parameters Analysis for Deep Weak Reflectors in the South Yellow Sea

The Mesozoic-Paleozoic marine residual basin in the South Yellow Sea(SYS) is a significant deep potential hydrocarbon reservoir. However, the imaging of the deep prospecting target is quite challenging due to the specific seismic-geological conditions. In the Central and Wunansha Uplifts, the penetration of the seismic wavefield is limited by the shallow high-velocity layers(HVLs) and the weak reflections in the deep carbonate rocks. With the conventional marine seismic acquisition technique, the deep weak reflection is difficult to image and identify. In this paper, we could confirm through numerical simulation that the combination of multi-level air-gun array and extended cable used in the seismic acquisition is crucial for improving the imaging quality. Based on the velocity model derived from the geological interpretation, we performed two-dimensional finite difference forward modeling. The numerical simulation results show that the use of the multi-level air-gun array can enhance low-frequency energy and that the wide-angle reflection received at far offsets of the extended cable has a higher signal-to-noise ratio(SNR) and higher energy. Therefore, we have demonstrated that the unconventional wide-angle seismic acquisition technique mentioned above could overcome the difficulty in imaging the deep weak reflectors of the SYS, and it may be useful for the design of practical seismic acquisition schemes in this region.

Accumulation conditions of outside source heavy oil in NepaBotuoba Sub-basin,Russia and prediction of distribution

In terms of tectonic evolution and petroleum geological conditions of the Nepa-Botuoba Sub-basin and its adjacent su4b-basins,the accumulation conditions of the heavy oil were analyzed. The studied area had plenty of oil and gas accumulation,but there were no developed source rocks. It is a typical outside source accumulation,whose origins from thick high-quality source rock deposited in the adjacent sub-basins. The shallow layer has favorable heavy oil reservoir conditions and poor sealing conditions,which benefits the thickening of hydrocarbon. The multi-periods of structural compression not only uplifted the studied area drastically,but also created a series of fault zones and large-scale slope belt. The structural compression also provided channel and sufficient power for migration of hydrocarbon to shallow layers. Based on these conditions,the favorable accumulation zone of heavy oil was predicted,which provided direction for heavy oil exploration in Nepa-Botuoba Subbasin.