Numerical simulation and development effect evaluation of coal-measure gas co-production in Dahebian block of Guizhou Province
WANG Wenkai
LIU Shiqi
LIANG Yu
DU Ruibin
Abstract：Coal measure gas has the characteristics of symbiotic co-storage and frequent inter-bedding of multi-lithologic reservoirs.Multi-layer commingled production is an effective way to achieve its efficient development.Taking the coal measure superimposed reservoir of the Upper Permian Longtan Formation in the Dahebian block of western Guizhou as the research object,the numerical simulation of the production of typical coal measure superimposed gas reservoirs with coal seam-sandstone-mudstone interbeds was carried out.The combined production effect of coal measure gas wells under different development intervals was discussed.The effects of gas production contribution,pressure conduction,and dynamic change of permeability on the development effect of coal measure gas were clarified,and the suggestions for the combined layer drainage of coal measure gas in the study area were put forward.The results show that the combined production effect of coal-bearing gas wells is affected by gas source supply,formation pressure conduction mode,and dynamic changes in reservoir physical properties.As a supplementary gas source,the non-coal seam section(mudstone and sandstone)has a certain contribution to the gas production of gas wells in coal measures.Among them,the combined mining effect of'coal seam+roof+floor'development mode is the best,and the cumulative gas production increases by 2.97％～48.46％,and the gas production contribution rate of non-coal seam section can reach 5.3％～10.4％.The gas production contribution rate of the non-coal seam section is controlled by the formation pressure conduction mode.Under the influence of vertical pressure difference between layers,the formation pressure drop is transmitted from the high-pressure zone of mudstone and sandstone to the low-pressure zone of coal seam,which controls the material transfer between layers.The development of multi-layer sections can slow down the vertical pressure conduction between layers,which is conducive to the expansion and decline of the internal pressure of the reservoir.However,too many development layers cause an increase in the vertical pressure difference between layers,which inhibits the expansion of the internal pressure drop of the reservoir.It indicates that the development of coal measures gas should be combined with the reservoir properties of the gas-bearing system to optimize the appropriate development layers.The dynamic change of permeability of mudstone and sandstone is significantly affected by the development mode.The development mode of multi-layer combined mining is conducive to the recovery of coal seam permeability,but it is easy to lead to the rapid decline of mudstone and sandstone permeability.It is particularly important to reduce or even avoid the damage of mudstone and sandstone reservoirs through reasonable drainage control technology.
Keywords：coal measure gasmulti-layer commingled productionpressure conductionpermeabilityDahebian block
Publication Date：2025-01-29
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：17( 98-114 )