Study on source rock potential and source rocks spatial distribution in the Manghan Faulted Sag, Kailu Basin

Manghan Faulted Sag is an exploratory target area in Kailu Basin. In order to determine its exploration prospect, the effectiveness of its source rocks is evaluated by organic geochemical behavior analysis of the samples, and their distributions are predicted using trace integration seismic inversion technology. Studies on their organic matter abundance, type and maturity indicate that the source rocks in the Sag have great generating potentials. Furthermore, it is found that, based on the spatial distribution predication, the source rocks in the Sag are well developed. Therefore, the Sag has a promising prospect for exploration.

Fluid Geochemical Features and Preservation Conditions of Marine Stratum in Typical Structure of Jianghan Plain Area

Many scholars carried out large quantity of researches on oil and gas preservative conditions of marine carbonate rocks from the aspects of cap rocks,faults,formation water,hydrodynamic,and tectonism.This article gives dynamic evaluation on oil and gas preservative conditions of marine stratum in Jianghan(江汉) plain of multiphase tectonic disturbance from the view of paleofluid geochemistry.The conclusion shows that there mainly existed fluid filling of two periods in the reservoir of Lower-Middle Triassic to Permian.The fluid filled in the earlier period came from Lower Palaeozoic.The interchange of fluid in Lower-Middle Triassic to Permian suggested the oil and gas in Lower Pa-laeozoic had been broken up.The fluid filled in the later period(Lower-Middle Triassic to Permian) came from the same or adjacent strata and lacked anatectic fluidogenous features coming from Palaeozoic.With good preservative conditions of bulk fluid at the time,the fluid of Lower-Middle Triassic to Permian and that of Lower Palaeozoic did not connect with each other.However,the hydrocarbon generation peak of marine source rocks had passed or the paleooil and gas reservoirs had been destroyed at that time and the marine stratum of Palaeozoic to Triassic in the research area did not put out commercial oil and gas flow.

A numerical investigation on deep shale gas recovery

In recent years,exploration and development of deep shale gas(at a burial depth of 3,500-4,500 m)has become a hotspot in the industry.However,the state of gas storage and transporting mechanism for deep shale gas under high pressure and temperature have not been thoroughly explored,compared with its shallower counterpart.A numerical model for deep shale gas recovery considering multi-site nonisothermal excess adsorption has been established and applied using Finite Element Method.Results from the simulation reveal the following.(1)Excess desorption significantly impacts early-stage performance of deep shale gas well;the conventional way for shallower shale gas development,in which the density of adsorbed gas is not distinguished from that of free gas,overestimates the gas in place(GIP).(2)Although thermal stimulation can speed up the desorption and transporting of deep shale gas,the incremental volume of produced gas,which is impacted not only by seepage velocity but also density of gas,is insignificant,far from expectation.Only an additional 2.03%of cumulative gas would be produced under treatment temperature of 190C and initial reservoir temperature of 90C in a period of 5 years.(3)Matrix porosity,which can be measured on cores in laboratory and/or estimated by using well logging and geophysical data,is the most favorable parameter for deep shale gas recovery.With 60%increase in matrix porosity,an extra 67.25%shale gas on a daily base would be recovered even after 5-year depletion production;(4)Production rate for gas wells in shale reservoirs at 3,500 m and 4,500 m deep would be raised by 5.4%in a 5-year period if the depth of target interval would increase by 340 m without thermal treatment according to the numerical model proposed in the study.

THE MAZHUANG RESERVOIR IN THE JUNGGAR BASIN (Ⅰ)——GEOCHEMICAL CHARACTERISTICS OF NATURAL GAS

The Mazhuang gas reservoir is located in the eastern part of the Junggar Basin. Itsgas-producing pool is averagely 2000 m deep. It is a mid-shallow reservoir. The natural gasrich 2--7% of C2-C4 gaseous hydrocarbons is mainly composed of methane. δ13CCH4. valuesare--47----45‰, heavier than microbiogenic gas, and lighter than coal--type gas as well asoil--associated gas. The maternal materials of gas source rocks are primarily from the type-Ⅲ organic matter at the low--mature stage （0.5%【R0≤0.8%）. The discovery of the reservoiris of great significance not only to the further exploration of natural gas but also to theenrichment of the gas--forming theory and the perfection of the classification of natural gastypes.