Shales Leaching Modelling for Prediction of Flowback Fluid Composition

Abstract

The object of the paper is the prediction of flowback fluid composition at a laboratory scale, for which a new approach is described. The authors define leaching as a flowback fluid generation related to the shale processing. In the first step shale rock was characterized using X-ray fluorescence spectroscopy, X-ray diffractometry and laboratory analysis. It was proven that shale rock samples taken from the selected sections of horizontal well are heterogeneous. Therefore, the need to carry a wide range of investigations for highly diversified samples occurred. A series of leaching tests have been conducted. The extracts were analyzed after leaching to determine Total Organic Carbon and selected elements. For the results analysis significant parameters were chosen, and regression equations describing the influence of rocks and fracturing fluid parameters on the flowback fluid composition were proposed. Obtained models are described by high values of determination coefficients with confidence coefficients above 0.99 and a relatively low standard deviation. It was proven that the proposed approach regarding shale leaching can be properly described using shale models at a laboratory scale, however scaling up requires further investigations.

Experimental study on the effect of tight gas fracturing flowback fluid composition on the performance of modified polyacrylamide viscosity reducing and slippery water system

“…The basis for flowback fluid reuse is mainly based on the additives formulated for the performance of the fracturing fluid, and the differences in the performance of the additives can lead to significant differences in the water performance indicators required for the fluid. The instability of the fracturing fluid performance configured by flowback fluid reuse usually manifests as lower viscosity, higher drag reduction rate, and increased rock damage compared to clean water when the same proportion of modified polyacrylamide is added to the flowback fluid 20–24 . Currently, in tight gas fracturing, the Southwest Oil and Gas Field of PetroChina typically uses modified polyacrylamide as the main additive to configure variable viscosity slick water.…”

“…The instability of the fracturing fluid performance configured by flowback fluid reuse usually manifests as lower viscosity, higher drag reduction rate, and increased rock damage compared to clean water when the same proportion of modified polyacrylamide is added to the flowback fluid. [20][21][22][23][24] Currently, in tight gas fracturing, the Southwest Oil and Gas Field of PetroChina typically uses modified polyacrylamide as the main additive to configure variable viscosity slick water. The main supplier of the agent is the Natural Gas Research Institute, and its chemical molecular formula is:…”