Coal reservoir characteristics and their controlling factors in the eastern Ordos basin in China

In the eastern Ordos basin, due to the diversity of the tectonic setting, coal rank, gas content and permeability, coal reservoirs have differing characteristics. In this paper, based on coal reservoir geometry, gas content, adsorption capacity, pores and fissures developments and permeability data, the coalbed methane(CBM) reservoir characteristics and their controlling factors in the eastern Ordos basin is discussed. The results show that, due to undergoing different paleo-temperatures in the geological history,coal rank has a higher trend from the north part to the south and from the shallow part to the inward basin, which determines CBM distribution and recoverability. In the north, although having large coal thickness and high permeability, Zhungeer-Xingxian coal rank is low, and gas content is small. In the central part, with medium rank, higher gas content and relatively high permeability, and the Wubao-Liulin area is the most favorable area in the eastern Ordos basin. In the southern part, medium and high metamorphism coal occurs, and although having the highest gas content, the permeability in the Hancheng area is low due to the development of sheared coal.

A Cretaceous Desert-Playa Sedimentary System Controlled the Potash Formation in the Simao Basin

Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits, including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine deposits. The Mangang Fm. composed of well-rounded quartz sandstones, were commonly considered as the bottom part of the Mengyejing salt series. Dttring last decades,

Combination and distribution of reservoir space in complex carbonate rocks

This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspian Basin.According to the reservoir space combinations,carbonate reservoirs can be divided into four types,i.e.,pore,fracture-pore,pore-cavity-fracture,and pore-cavity.Formation and distribution of these reservoirs is strongly controlled by deposition,diagenesis,and tectonism.In evaporated platform and restricted platform facies,the reservoirs are predominately affected by meteoric fresh water leaching in the supergene-para-syngenetic period and by uplifting and erosion in the late stage,making both platform facies contain all the above-mentioned four types of reservoirs,with various pores,such as dissolved cavities and dissolved fractures,or structural fractures occasionally in favorable structural locations.In open platform facies,the reservoirs deposited continuously in deeper water,in an environment of alternative high-energy shoals（where pore-fracture-type reservoirs are dominant） and low-energy shoals（where pore reservoirs are dominant）.

Dynamic Analysis on Rifting Stage of Pearl River Mouth Basin through Analogue Modeling

The Pearl River Mouth basin （PRMB） is a marginal sedimentary basin of the South China Sea. It trends NE and is divided into three segments from west to east by two NW-trending faults. Changing dramatically in structures along and across strike, the PRMB is a good example to analyze main factors that might control the process of a continental rift basin＇s extension. Through five series of analogue experiments, we investigate the role of different factors, such as pre-existing discontinuities of crust, rheological profiles of lithosphere, kinematics of extension and presence of magmatic bodies and strong crustal portions （rigid massifs） on the development of basin＇s structures. After being compared with the architecture of the natural prototype, the results of the analogue models were compared with the architecture of the natural prototype and used to infer the role of the different factors controlling the formation and evolution of the PRMB. The main conclusions are as follows. （1） Affected by pre-Cenozoic structures, the PRMB was controlled by crosscut NE- and NW-trending initial faults, and the NW-trending Yitong＇ansha （--~l~） fault may be a through-going fault along dip and offset the NE-trending rift and faults, while the Enpingdong （和统暗沙） fault might exist only in the middle and south. （2） The NW-trending faults may orient WNW to be sinistrally transtensional under SE to nearly NS extension. （3） The thickness ratio of brittle over ductile crust in Baiyun （白云） sag is lessthan normal, suggesting an initially hot and weak lithosphere. （4） The magma must have taken part in the rifting process from early stage, it may occur initially upon or slightly south of the divergent boundary in the middle segment. The flow of magma toward rift boundary faults caused extra vertical subsidence above the initial magma reservoir without creating a large extensional fault. （5） The rigid massif contributed to the strain partition along and across basin strike.