Research on low damage fracturing fluid in tight gas reservoirs and its application

Tight gas reservoirs feature in low porosity, low permeability, low pressure and strong water locking. The single-well productivity after fracturing will be negatively influenced by reducing the extraneous fluid invasion, accelerating the back-discharge of fracturing fluid, and increasing the back-discharge rate. Based on fully recognizing the geological features of the He1 member of Shihezi formation and the Shan1 member of Shanxi formation of the Upper Paleozoic gas reservoir in Tabamiao area of northern Ordos Basin, a lot of lab research is conducted on the N2 enhanced water based fracturing fluid, aiming at as much as possible lowering the damage caused by the invasion of fracturing fluid into the reservoir. Lab research shows that the N2 enhanced water based fracturing fluid can be used to better reduce the surface tension in the capillaries in the reservoir pore throats, favorable for the back-discharge of residual fracturing fluid, lowering the damage to the formation. The properties of the fracturing fluid meet the requirement of the fracturing process on reservoir reconstruction. Field application indicates that the formula system of the fracturing fluid could better meet the requirements of the fracturing process and the physical properties of reservoirs, increasing the back-discharge rate of the fracturing fluid after fracturing, and realizing higher single-well productivity. 