Study On The Development Law Of Horizontal Wells In Ultra-Low Permeability Reservoirs

At present,drilling technology and experience in horizontal wells has been relatively mature.However,the research on the development law of horizontal wells in ultra-low permeability reservoirs is not deep or comprehensive enough.These kinds of reservoirs are usually developed by water flooding and large-scale fracturing further aggravates their heterogeneity.As the contradiction of horizontal well development is becoming increasingly prominent,there is an urgent need to analyze the typical developed blocks in order to figure out the development law,which lays the foundation for the subsequent energy replenishment technology.This paper is based on the actual production data of horizontal wells in M wellblock,A oilfield and centered on dynamic analysis and reservoir engineering method.The research analyzes the development effect,the decline law and the water content variation characteristics of horizontal wells.The results show that:(1)it is more objective to evaluate the development of horizontal wells using index,“contribution rate of horizontal section per unit length” and the fracturing scale of single section should be increased in the process of project design.(2)the production decline of fractured horizontal wells in the study area are divided into four types and empirical formulas of production decline are established for horizontal wells suitable for the study area.Main influencing factors of production decline are matrix permeability,fracture length of main flow fracturing and water injection rate.(3)this article classifies the water content variation characteristics.It is considered that the complex fracture system formed by large-scale fracturing and microfractures of reservoir itself are the main causes of water cut rise.