Study Of Foam Fracturing Fluid And Evaluvation Of Properties For Coal Rock Of Qinshui Reservoir

Coal Bed Methane is a?unconventional gas,it is generated by coal seam and as a major reservoir of adsorption state in coal seams. It is nearly two decades the rise of high-quality clean new energy for shallow depth with the development, less investment and exploration risk ,quick features and so on.It has the utilization of great prospects. Exploitation of coalbed methane wells are often fractured, commonly used in foreign countries fracturing fluid system include: water, foam fracturing fluid and polymer fracturing fluid and so on.The invation of fracturing fluid will lead to damage and decrease permeability of the reservoir,it was caused by blockage of coal matrix and water lock effect, blockage of coal matrix will limit the CBM desorption,so foam fracturing fluid conducive to back row for less fluid and can effectively reduce the damage to the coalbed methane reservoir wells.In this thesis, we got the recipe of foam fracturing fluid system by Screening foaming agent and foam stabilizing agent as SL-1, SL-2, Nina Er, AES, ABS, and dodecyl dimethyl betaine and so on.By deteminating the Performance of the foam fracturing fluid show that: foam fracturing fluid with high viscosity, high consistency coefficient, low filtration characteristics, research shows that:settling velocity of ceramsite in the foam fracturing fluid is only 0.0045 to 0.014 percent in the water.It is also much smaller than conventional fracturing fluid, of which 0.25% SL-1 +0.25% SL-2 +0.5% ABS +0.2% PAM system is the best.The experiments of adsorption and scanning electron microscopy studies have shown that: foam fracturing fluid in the pores of the coal matrix adhesion to a lesser extent and nearly no blocking of coal pores.During the process of back row, the foam fracturing fluid is based mainly in the form of liquid,in this paper,we determine the damage of coal rock permeability which was caused by foam fracturing fluid, the results show that:the damage rate of 0.25% SL-1 +0.25% SL-2 +0.5% ABS +0.2% PAM system is the smallest.and only to 19.71%, compared to guar gum on the damage rate of 79.4%, foam fracturing fluid is better. To the TS57-01 Well 3# coal seam in southern Qinshui Basin, we use the optimal foam fracturing fluid to simulate fracture by the FracproPT fracturing software.The results showed that: the fracture half-length of 0.5% SL-1 +0.5% ABS +0.2% PAM system and 0.5% SL-2 +0.5% ABS +0.2% PAM system is the best and reach to 186m,but the width is narrow, the average slit width is only 1.6cm, the flow conductivity of fissure is relatively poor,while the 0.25%SL-1+0.25%SL-2+0.5% ABS +0.2%PAM system's fracture half-length is relatively short, but the slit width is better and up to 2cm, so the flow conductivity of fissure is better and carrying capacity and anti-filtration ability is much strong.