Characteristics of Gas-Water Two-Phase Flow in the Presence of Fracturing Fluid一Take Sulige Gas Field as an Example

Abstract

The tight sandstone reservoir in He8 member of Sulige gas field is mainly developed economically and efficiently by fracturing technology. In the process of fracturing, the filtration of fracturing fluid will cause damage to the reservoir, which will affect the gas-water seepage in different degrees. It is an essential key link in the reasonable development of tight sandstone gas reservoir to make clear the characteristics of gas-water seepage under the participation of fracturing fluid. Taking the core and gas and water of He8 member in Sulige gas field as samples, the adaptability of fracturing fluid damage is evaluated by studying the experiments of fracturing fluid sensitivity damage, micro interpretation of NMR, surface properties of liquid phase, etc.; the difference of gas-water phase permeability curve with and without fracturing fluid participation is compared by gas - (formation water + fracturing fluid) phase permeability experiment, and the influence of fracturing fluid participation on seepage is analyzed. Experiments show that fracturing fluid causes reservoir sensitivity damage and water lock damage, reduces the relative permeability of the liquid phase, and its damage degree to the reservoir can be determined quantitatively; in the matrix system and matrix fracture system, fracturing fluid filtration will lead to the change of core pore throat structure and the increase of immovable fluid, and the average damage value of gas-water two-phase flow of fracturing fluid in the study area is 32.7%, with the backflow of fracturing fluid fracturing filtrate, the participation of fracturing fluid fracturing filtrate reduces the relative permeability of gas phase and water phase; fracture can significantly improve the gas-water seepage situation, and the absolute permeability after fracture formation is 32.9 times of that before fracture formation. The study of gas-water two-phase percolation with the participation of fracturing fluid provides a strong theoretical support for the rational development of tight sandstone gas reservoir, which is of great significance to improve the recovery and development effect of natural gas in tight gas reservoir.KeywordsSulige gas fieldFracturing fluidSeepage characteristicsSensitive damageFracture making