Method for selecting the optimal fracture geometry to improve the efficiency of hydraulic fracturing at a field in Western Siberia
Key words: hydraulic fracture treatment, Young’s modulus, proppant, fracture width, fracture permeability, proppant embedment, proppant damage
Authors: V.O. Polezhaev (RN-BashNIPIneft LLC, RF, Ufa), B.O. Mikhailov (RN-BashNIPIneft LLC, RF, Ufa), D.V. Logachev (RN-BashNIPIneft LLC, RF, Ufa), K.R. Ibragimov (Slavneft-Megionneftegas PJSC, RF, Megion), A.F. Mingazov (Slavneft-Megionneftegas PJSC, RF, Megion), V.R. Tuygunov (RN-BashNIPIneft LLC, RF, Ufa; Ufa State Petroleum Technological University, RF, Ufa)
The productivity of each fracturing well decreases over time, and this can lead to economic inefficiency in the development of low permeability reservoirs. The reason may be a suboptimal design of the hydraulic fracturing, in which the width of the fracture is too narrow. After hydraulic fracturing, each fracture begins to degrade under the action of a closing stress: proppant is pressed and destroyed, particles are removed, and the proppant pack is re-compacted, which negatively affects the conductivity and permeability of the hydraulic fracture. To solve this problem, methods proposed by M. Economides in the book “Unified fracture design” have been taken as a basis. To the calculations described in this book, a change in the crack width due to the above effects was added and the optimal crack width for low-permeability reservoirs was calculated. By creating a wider fracture, it is possible to significantly increase its life, reduce the rate of decline in cumulative production, and also save on re-stimulation of the reservoir. Ultimately, a formula was derived (based on calculations by M. Economides) for calculating the optimal crack width, which takes into account the proppant indentation into the rock, fracture and re-compaction of the proppant pack under the pressure of the fracture closure. The change in permeability under the influence of the previously mentioned parameters is calculated.
It can be stated with confidence that the methodology of M. Economides does not work in real conditions in low-permeability reservoirs, and with the help of an improved method, it is possible to carry out rapid selection of the optimal fracture geometry, as well as increase the efficiency of hydraulic fracturing in reservoirs of this type.
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