Study of fracturing fluid re-discharge based on percolation experiments and sampling tests – An example of Fuling shale gas Jiangdong block, China

Abstract

Shale gas development requires the use of hydraulic fracturing, and the relationship between fracturing fluid drainage and production is not clear. Therefore, it is necessary to adopt the method of core experiment combined with engineering validation to achieve the description of the seepage-absorption-return mechanism of shale and to optimize the selection of fracturing fluids and the testing work system in engineering. In this study, a “seepage experiment → sampling test → engineering validation” working procedure is proposed, and it is found that seepage occurs only on the surface of the fracture where the liquid medium intrudes into the fracture and that the amount of water absorbed is directly proportional to the area of seepage; the rate of return is inversely proportional to the production rate in the same secondary tectonic unit; and the absorption rate per unit area of four types of cores with the same surface area is directly proportional to the yield of the fractured shale in the same medium. Under the premise of the same medium, the water absorption per unit area of the four types of cores varies with the rate of change with time, but the general trend is the same. Under the premise of different secondary tectonic units, when the time of good closure is similar, the correlation between the return rate and the test production is weak.

Keywords

• shale gas
• fracturing fluid
• imbibition
• backward discharge
• sample survey