Wellbore Stability Evaluation Of Penglaizhen Formation Of Shifang Field

The gas resource quantity of Shifang field Penglaizhen formation is huge, has broad prospects for exploration and development.However,due to complex geological conditions,strong reservoir heterogeneity,easy to collapse shale and natural fractures,resulting in a series of underground complex problems,seriously affected the progress of the drilling project,which restricts the entire gas reservoir Penglaizhen formation exploration and development work.In this paper,the theory and methods of petroleum geology and tectonics,geophysical logging,rock mechanics and engineering,reservoir engineering and drilling engineering based,and it combines with previous research results,making system analysis of rock mechanics, formation pore pressure,stress,collapse pressure,fracture pressure and other parameters and characteristics,doing a comprehensive study on the wellbore mechanical stability,and put forward countermeasures of drilling technology.This paper is in a comprehensive collection of drilling,logging,testing and reservoir reconstruction and other related information, through experiments and geophysical logging data combined approach to establish a predictive model for rock mechanics parameters and profiles. Established the formation pore pressure prediction model and a cross section with Eaton method.The use of peripheral imaging logging data and micro-seismic data clearly the maximum horizontal stress of Penglaizhen formation direction for the near east-west.In a preferred wellbore instability criterion,it establishes the formation collapse pressure,fracture pressure prediction model and the corresponding profile of Penglaizhen formation. Shifang regional collapse pressure increases with depth, and above Penglaizhen formation formation collapse pressure is less than the pore pressure.Drilling fluid density which based on pore pressure can maintain wellbore stability.Burst pressure between 2.39~ 3.31MPa/100 m,far higher than the formation collapse pressure and pore pressure. Basically there is no this condition that drilling crushing stratigraphyic.Meanwhile,the combined analysis of the data obtained,it puts forward area drilling technology in drilling engineering to provide fundamental basis for design and construction.The research results in this paper will service subsequent drilling and completion engineering,and it will reduce the underground engineering status effectively,improve the drilling efficiency,shorten drilling cycle,reduce drilling cost.It has important realistic significance on the realization of Shifang field Penglaizhen formation efficient gas exploration and development.