Large-scale laboratory study on the evolution lawof temperature fields in the context of underground coal gasification

This article presents the evolution law of temperature fields in a large-scale laboratory Underground Coal Gasification reactions using Ulanqab lignite under actual conditions.The results show that in the cultivation stage of oxidation zone,the main direction of the temperature field expansion is consistent with the crack direction of the coal seam.In the gasification stabilization stage,the main direction of the temperature field expansion is along the channel.The temperature of the coal seam and the overlying rock mass at its interface with the furnace directly above the gasification channel is equivalent to that of the coal seam temperature,and this temperature is much greater than the temperatures observed near both side walls of the gasification channel at the interface.However,temperatures perpendicular to the axis of the gasification channel are similar at a vertical distance of 40 cm away from the interface.The temperature distributions indicate that the transmission of heat through the overlying rock mass is more rapid in the vertical direction than in the horizontal direction.Moreover,some degree of thermal dispersion is observed in the vertical direction near the outlet.The thermal dispersion coefficient is 0.72 and dispersion angle γ is 78.7°.

Effect evaluation of shale types on hydrocarbon potential using well logs and crossplot approach,Halewah oilfield,Sab'atayn Basin,Yemen

Log-analysts typically distinguish three types of shale distribution in clastic reservoirs,that is,laminated,dispersed and structural distribution,which tend to influence the effective porosity and permeability of reservoirs.The Alif Member is made up of sandstone interbedded with some shale,with shale dominating on top and at the bottom.In sedimentary formations,the gamma ray log normally reflects the shale content.The gamma ray log and neutron-density porosity crossplot is used to estimate a reservoir's shale volume(Vsh),according to which the Alif Member is divided into three zones.In addition,shale types are recognized by neutron-density porosity crossplot,and the correlation coefficients of gamma ray log-based Vsh and neutron-density porosity-based Vsh are suggested to be reliable.The Vsh and shale types of the three zones are compared against the reservoir's potential to yield hydrocarbons.The major oil intervals mainly concentrate in shaly sand and sandstone zones of dispersed and laminated shale types.The third zone,the lowermost interval,contains pure shale of laminated type and is considered out of reservoir standards in hydrocarbon production due to its excessive shale volume.Quantitative assessment of shale type distribution and Vsh by crossplot approach could not furnish correct information to evaluate massive shale intervals.