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Coal Rock Characteristics And Fracturing Metholds For QinShui Reservoir

Posted on:2011-05-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:T T LuoFull Text:PDF
GTID:1100360308959340Subject:Oil and gas field development project
Abstract/Summary:PDF Full Text Request
Coal-Bed Methane(CBM), unconventional natural gas, is generated and mainly adsorbed in the coal. Accelerate exploiting coal-bed methane resources can ease the situation of shortage natural gas in China and increase self-ability of domestic energy. For domestic technology delay, most of methane directly release into atmosphere and cause serious hazard for environment. methane gas maybe expose in the process of exploitation coal. The effective using of CBM becomes an important issue for people. Based on Qinshui Basin, the paper studies the geological characteristics of the coal reservoirs, viscoelastic surfactant fracturing fluid and finally design and analysis fracturing performance by FracproPT software.Structure characteristics and reservoir of Qinshui basin shows that the reservoir pressure is generally less than 10MPa, some more than 10MPa, porosity rang from 5%to10%, and permeability varies greatly (range from 0.5 to 8md), Regional distribution is"high Southern and low northern","high wing and low axial".Based on intrusive mercury curve of the coal reservoir, the coal reservoir can divide into fractured– porous style and micro-pore style. The pore structure parameters show that the k /Φvalue increases, the displacement pressure decreases, the average pore throat radius, the value of pressure decrease, and the maximum pore radius increases. The area eigenvalues show that Selection sorting coefficient is 2.077~16.745, Pore throat variation coefficient C is 0.168~0.753, Skewness of pore and throat is -1.644~1.662, Fractal dimension between 2.7~ 2.9.Calculated acoustic wave test pattern can show elastic modulus, Poisson's ratio and other parameters of coal samples, acoustic properties of rock can also calculate the parameters such as compression, tensile strength and other strength parameters. The results show that the area is unconventional reservoirs: relatively high Young's modulus, high Poisson and low hardness, easy to broken, highly sensitive and strong stress sensitivity of strata.Research the viscoelastic surfactant system and evaluate the formula performance. The Viscoelastic surfactant shows good performance of sand carrying, resistance to shear capacity, large amount of the beginning filtration and small filtration coefficient. The systems have good performance of back row for gel viscosity less than 10mPa.s after breaking. Coal damage results show that the smaller pores of coal the slower permeability recovery. The coal after saturated liquid is more compression and shear, compressive and shear strength of saturated fracturing fluid coal sample coal are better than another of saturated water. In addition, experiments shows that discipline of viscoelastic surfactant adsorption in coal consistent with the law of Langmuir adsorption, the adsorption enthalpy change is negative means that adsorption is spontaneous.Combination of formation parameters measured by acoustic time test chart and viscoelastic surfactant properties. Use FracproPT software design and simulate hydraulic fracturing, comparison crack geometry and stress fitting. Fitting show those viscoelastic surfactants fracturing fluid have good performance and fully meet requirements of the region.
Keywords/Search Tags:Qinshui Basin, Basic characteristics of the reservoir, Pressure mercury curve, Acoustic test chart, Viscoelastic surfactant, Fracturing fluid, Fracturing design and analysis
PDF Full Text Request
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