Study On Optimization Method Of Well Pattern In Tight Reservoir Based On Production Potential

Tight oil reserves are very rich in China,which has become the focus of research in the field of unconventional oil and gas resources in recent years.Tight reservoir not only has the general characteristics of continental clastic reservoir,but also has the geological characteristics of low porosity,low permeability,fracture development and strong heterogeneity.Therefore,higher requirements are put forward for the well pattern optimization design of tight reservoir.Through mathematical analysis and numerical simulation,this paper studies the production potential method,well pattern optimization theory,well pattern form optimization and well pattern parameter optimization design of tight reservoir,and obtains a complete well pattern optimization method of tight reservoir.The main achievements are as follows:(1)The traditional calculation method of reservoir production potential is improved,and the improved calculation method of reservoir production potential is put forward.Three calculation methods of production potential,original reservoir production potential and reservoir reserve abundance of improved reservoir are compared and analyzed.It is concluded that the production potential of improved reservoir can reflect the development value of different areas of reservoir better than the production potential and reservoir reserve abundance of existing reservoir,and can be used as the basis for optimizing the dominant well distribution area of tight reservoir.(2)The adaptability of horizontal well in tight reservoir is analyzed.The optimization model of horizontal well pattern optimization method is studied.The optimization problem of horizontal well pattern is reduced to the problem of finding the optimal value mathematically.Three optimization algorithms,gradient method,random disturbance approximation algorithm and particle swarm optimization algorithm,are studied.The optimization process of constrained optimization method is obtained.(3)With the increase of the angle between the horizontal well section and the fracture,the final recovery rate is lower and lower,and the water breakthrough time is earlier and earlier.Under the condition of natural fracture development in tight reservoir,five point well pattern is adopted to arrange horizontal well parallel to natural fracture,with the highest recovery degree,the latest water breakthrough time,the slowest rise of water content and the best development effect.(4)The optimal length of fracturing production well is about 750 m,and the optimal length of water injection well is about 550 m.The vertical position of horizontal well has little effect on the development of tight reservoir.The best matching relationship between horizontal well spacing and row spacing is 300-350 m,and the best row spacing is 300-350 m.