Case Study: Massive hydraulic fracturing in volcanic gas, China

Abstract

This paper details the design and execution of 4 massive hydraulic fracturing in low permeability volcanic reservior in NP oilfield, north China. The top burial of target gas bearing D1 range from 4317m to 4962.6m, and the intervals range from 36.8 m to 161.8 m. The porosity and permeability vary from 1.76% to 8.13% and less than 0.1×10 -3 μm 2 to 0.61×10 -3 μm 2 respectively, with average poisson's ratio and Young's modulus at 0.35 and 52800 MPa respectively. The reservoir temperature of the 4 wells are between 162℃ and 183℃, which update the highest temperature record in China fracturing history till now. Additionally, FMI results show that the natural fractures are widely distributed in the gas reservoir.According to the characteristic of the reservoir, we brought forward a systematic hydraulic fracturing technology which included: CMHPG rating of temperature 180℃ with lower concentration and lower damage, high strength ceramic proppant with different types and sizes, a new kind of mini-fracturing, a new optimization technique of fractures and treatment parameters.The total fracturing fluid and total proppant varied from 602 m 3 to 1020 m 3 and 47 m 3 to 105 m 3 . Post-analyses indicate that the density of the natural fractures determines the net pressure, and also determines whether the treatment was difficult or not.The experience can direct the treatment in the similar gas reservoir.

Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

“…The abundance of calcite, dolomite, and pyrite is nearly zero. Quartz is a mineral important in improving the efficiency of hydraulic fracturing [35]. Clays have a large effect on the adsorption of fracturing fluid in volcanic reservoirs [36].…”