Optimization Of Process Parameters For Volumetric Acid Pressure In Tight Gas Reservoirs

The results of micro-seismic monitoring and field tests show that complex etching network fractures tend to be form during volume acid fracturing in fractured tight gas reservoir.It is difficult to simulate the extension process of complex network fracture by using classic two-wings fractures extension model.So network fractures parameters and construction parameters which cannot be optimized might lead to an inappropriate acid fracturing design.Therefore,it is necessary to establish a complex network fractures expansion and extends and etching numerical model suitable for volume acid fracturing.This model can reflect the nature of hydro-etched network fractures expansion extends mode,simulate the process of volume acid fracturing,guide acid fracturing design and greatly improve the acid fracturing result.Though a deep research of hydraulic fracture propagation model and the mechanism of natural fractures intersect with the role of hydraulic fractures,this paper studied fracture propagation model?hydraulic fracturing and natural fractures encounter case judgment model and etching network fractures mode and formed an improved simulate approach for complex hydro-etched network fractures.The main results are as follows:(1)Considering the M-C initiation condition and the interaction between the far-field in situ stress and the fracture tip stress,this paper established a he hydraulic fractures with natural fractures encounter case judgment model which provided a mechanics guidelines for complex network fractures expansion and extends simulation.This paper also get main factors that effects of hydraulic fracturing and natural fractures effect hydraulic fracturing and natural fractures intersection by using orthogonal experiment:coefficient of friction>the level of stress difference>approach angle>tensile strength of rock>cohesion.(2)The group of hydro-etched network fractures expansion simulation model was established by deriving hydraulic fracture propagation 2D model and acid-rock flow reaction model,coupling with hydraulic fracturing and natural fractures encounter case judgment model?discrete natural fracture network model.Moreover,this paper also designed a reasonable computer algorithm,developed a program of complex network fractures expansion and formed an efficient way to track the process of complex network fractures expansion.Above-mentioned works provided a basis for acid fracturing design optimization(3)A method of volume acid fracturing parameter optimization was established to achieve a complex fracture network expansion extended configuration,fracture network parameters and construction parameter optimization.Based on the dynamic expansion extends simulation of complex hydro-etched fracture network,volume acid fracturing productivity prediction model was established to study production dynamic characteristics influence of multiple sets of process parameters,to reveal seepage law and hydrodynamic behavior characteristics of volume acid fracturing in tight gas and oil reservoir.With the objective of maximizing production capacity,this paper optimized the volume acid fracturing parameters and predicted the effect after process.The research results are important for guiding the design of volume acid fracturing and estimation of fracture network parameter after volume acid fracturing.The results also provide research ideas and methods for fracture extension simulation in similar reservoir in the future.