Study On Water Lock Effect Of Hydraulic Fracturing Exploitation In North Guizhou Shale Gas Reservoir

Shale gas will be one of the most important energy sources in the future which as an efficient and clean unconventional energy source.Nowadays shale gas mainly exploited by hydraulic fracturing,water lock effect will be produced during hydraulic fracturing.In low permeable strata,the water lock effect on shale gas exploiting is very important and even becomes the bottleneck of shale gas exploiting.It is of great significance to handle the water lock effect in the process of shale gas production by hydraulic fracturing.This text is based on the low permeability shale of Fenggang parameter wells in the northern Guizhou Province area as the subject investigated.To deal with the water lock effect mainly study based on the combination physical properties experiments and hydraulic fracturing experiments under simulated stratigraphic conditions.This paper analyse the physical property of the shale in this area,evaluate the valve of exploration,combination of physical propety with different content proppant、surface active agent and other agents for single factor treatment.Finally,we are sure to adopt fracturing fluid.The results of comparative analysis of the samples by physical experiments after hydraulic fracturing experiments were conducted on the samples,then choosing permeability and flowing water content as evaluation index to evaluate the damage recovery of water lock effect after treatment.We can draw the following conclusion:(1)Through analysis of physical property,the TOC content in this area is high,it has great exploration value,however,the most content mineral is quartz;The pore and pore throat distribution of shale mainly in microns,the pore shape is irregular spherical,triangular,elliptic;The content of bound water in the shale is high,shale gas has well preservation conditions.(2)Organosilicon surfactants were synthesized from allyl polyethylene glycol,epichlorohydrin,hydrogenated silicone oil and organic amine as main raw materials.This active agent has lower surface tension,as least to be better 23.8mN/m.The fracturing fluid has good fusion and high stability,it has fine compatibility and sand-carrying capacity.(3)Hydraulic fracturing under simulated reservoir conditions,choosing single factor as proppant and surfactant,contrast between single factor experimental results with different content,we confirm the single factor content was 1% and 2%,respectively.As a final,determining the ratio of synthetic fracturing fluid.(4)Choosing permeability and flowing water content as evaluation index,the water lock effect is high of Fenggang parameter well in the Northern Guizhou Province area,up to 80%.The maximum recovery degree of water lock effect of proppant,surfactant and synthetic fracturing fluid can reach 43.884%,78.437%,83.464%,respectively,they have high degree of recovery.It has guiding significance for treatment of water lock effect in the low permeable shale gas mining process in the Northern Guizhou Province area,also has reference significance for treatment of water lock effect in other areas.