Water Absorbing Ability Of Shale Gas Reservoir In Hunan And Its Impact On Deliverability

Shale reservoir clay content is higher,after the fracturing fluid into the reservoir,it will react with the clay,the strength of the shale itself and permeability reservoir will be reduced,it will have a great influence on the formation of the joint after the fracture network,understanding of reservoir clay water absorbing capacity and its sensitivity,it is very important to improve the efficiency of transformation.In this paper,brittle shale developed of Baojing Block of Longmaxi Formation was studied.casting thin section?SEM and CT was used for microscopic analysis,The CST,conductivity experiment and spontaneous imbibition experiment have been performed by the application of distilled water,KCl solvent,slippery liquid and surfactant.The comparison of sandstone?Yingcheng Formation?Longmaxi Formation? Niutitang Formation? marine shale of Lujiaping Formation? continental shale of Chang 7 formation have been conducted.These experiments describe the adsorption capacity of clays in gas shale from macroscopic point,at the same time,the damage mechanism of clays on gas shale from microscopic point.Through the study found that: the salinity content of marine shale is far larger than that of continental shale,which can produces high osmotic pressure that plays an important role in generating cracks in the process of imbibition.Marine shale clay content is mainly illite,particles are easy to transport,Continental shale clay content is mainly illite mixed layer,which is easy for hydration expansion,its water absorption ability is strong,the kinds of clay play an important role;in addition to capillary force,clay is a key factor in shale reservoir,water absorbing ability of shale reservoir is much higher than that of conventional reservoir;permeability and porosity of shale reservoir in Baojing Block is low,its basic physical property is poor.After long-distance horizontal fracturing in Baoye 3 XF well,clay minerals?pressure coefficient and stress sensitive are the main factors affect deliverability.It is great important to the efficient development of gas shale if the action of clays in gas shale have been clearly understood.