New productivity evaluation model for segregated fracturing horizontal well in low permeability and tight reservoir
Dawei Zhu, Zhengming Yang, Xuewu Wang, Zuocai Liao
a.Institute of Porous Flow and Fluid Mechanics, CAS, Langfang 065007, China
b.University of Chinese Academy of Sciences, Beijing 100049, China
Different from the previous research based on the linear flow model of Darcy’s law, the paper established a model which considered the nonlinear seepage in the low permeability and tight reservoir by coupled numerical solution of the four divided flow fields, namely, nonlinear elliptic flow in the medium, linear flow and radial flow in the fracture, hydraulic pressure drop flow in the horizontal wellbore based on the theory of elliptic flow, superposition and equivalent radius principle. The comparison of productivity of nonlinear flow model, Darcy flow model and pseudo threshold pressure gradient model was presented. Fracture-controlled productivity was analyzed. Factors influencing horizontal well productivity, fracture number, length and conductivity, for instance, were studied .As a consequence, fracturing parameters for low permeability and tight reservoirs were optimized. The results show that the calculation productivity of the new model which considers nonlinear flow is closer to the actual production of the segregated fracturing horizontal well in operation which indicates the reliability of the new model. Besides, the calculation productivity of the new model is between that of Darcy’s linear flow model and pseudo threshold pressure gradient model. Fracture-controlled productivity varies from the heel to the end which is low in center while high in edges. The fractured horizontal well productivity viscously increases with the number, length and conductivity of hydraulic fractures. With respect to the low permeability and tight reservoir, fracture parameters optimization can be achieved by the presented model. Meanwhile, the presented model is also appropriate for the productivity evaluation and fracture parameters optimization for med-high permeability reservoir which follows Darcy’s linear flow model by taking suitable nonlinear coefficient.
Keywords: low permeability and tight reservoir; segregated fracturing horizontal well; nonlinear seepage flow; coupled solution; productivity
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