A Study And Application Of Fracturing On Low Permeability Bottom-Water Driven Reservoir

After about 60 years of development, hydraulic fracturing technology has been improved from single well fracturing to integral fracturing, fracturing of low permeability reservoir to high-permeability reservoir fracturing, vertical well fracturing to horizontal well fracturing and fracturing in oil-water wells to coalbed methane well fracturing. With regard to the low permeability bottom water reservoir fracturing, the fracture could not be controlled effectively in vertical direction since the interlaminar stress contrast is not big enough or there is no barrier which could generate interlaminar stress contrast, so the hydraulic fracturing will fail because the induced fracture would extend into bottom aquifer in the vertical derection and cause the oil well sudden water flooding once the bottom water flow into the wellbore along the fracture. The problem of low permeability bottom water reservoir fracturing hasn't been solved well and the related reports is very few.This paper take the integration of measures including theoretical investigation, numerical simulation, laboratory test and field test. According to the fracture mechanics, this paper establish the fracture vertical extending mathematical model and similarity criteria of physical simulation of hydraulic fracturing on the basis of similarity theory, analyse the effect of vertical heterogenize on the vertical extending of the fracture quantitatively, carry out experiments hydraulic fractring by a large-size triaxial simulator, set up the mathematical model of rock mechanics parameter on the basis of well-log information, develop the software of forecasting rock mechanics parameter on the basis of conventional well-log information, study the technology of controlling the fracture downward extending on bottom water reservoir, develop new sinking diverting agent made of thermoset resin, solidifying agint, stuff, carrier fluid for carrying the diverting agent and non-residue fracture fluid and design site operation technology and construction parameter. We achieved remarkable results after field practice.The results are showed below(1) Analyse the effect of vertical heterogenize on the vertical extending of the fracture quantitatively theoretically: Interlaminar stress contrast of the rock plays an vital role in the vertical extending of fracture and expanded range, fracture toughness of rock could control the vertical extending of induced fracture, the fluid gravity gradien will make the fracture extend downward and the stress gradient of rock will have the adverse effect on it.(2)Carry out the physical simulation of hydraulic fracturing on the basis of similarity criteria. In accordance with the experiment, interlaminar stress contrast and the properties of bed interface play an important role in the vertical extending of fracture and the interlaminar physical parameters difference will not affect the extending of the fracture into the barrier through the bed interface.(3)Develop the software of forecasting rock mechanics parameter which could forecast rock mechanics parameters on the basis of conventional well-log information.(4)Develop carrier fluid and non-residue fracture fluid which is easy to prepare, it has the properties of automatically breaking, free solid and non-residue. (5)Develop the new sinking diverting agent which has Independent intellectual property rights, the agent could control the downward extending of the fracture effectively and stop the bottom water flow upward into the wellbore.(6)Study the technology of controlling the downward extending of fractre and present the technology of using artificial barrier to control high in hydraulic fracturing through multi-level filling. Field practice shows that the technology is innovative.