Increased Drilling Efficiency of Gas Storage Wells Proven Using Drilling Simulator

Abstract

Abstract Gas storage wells are being drilled in Nova Scotia, Canada for natural gas storage in underground rock and salt caverns. A study was performed to evaluate the efficiency of the drilling of these wells. Utilizing a drilling simulator where drilling operational or log data is required to generate a drillability log or apparent rock strength log (ARSL) offset gas storage wells in the area were analyzed. The sonic log data from the offset wells were utilized to calculate the ARSL and the formation information was obtained from strip logs. The actual drilling of the next gas storage well was then simulated and optimized using the commercially available drilling simulator. The optimization process proved that the potential for reducing drilling cost is more the 30 percent. This is a typical cost reduction that can be obtained utilizing drilling simulation on conventional wells in other areas of Canada were only a few offset wells have been drilled. The analysis proves that even with unconventional drilling like for gas storage well with larger hole sizes and the utilization of hole openers the cost reduction potential is the same as with conventional drilling. This paper presents the field data utilized and the results from the simulation study including the economical analysis. Introduction Drilling cost is a major part of oil well developing expenses. It consists mainly of the rig costs, bit costs and service costs. The rig cost is usually the larger part of the drilling cost. It is a direct function of drilling time used to finish a well and increases linearly with it. Drilling time spends to rotate the bit, connect the pipes and move up and down the drill string (tripping) to change the bit or for other reasons. The connecting time is fixed for a normal drilling operation of a specific interval. On other hand, an optimum drilling plan can reduce the rotating time by increasing rate of penetration (ROP) and decreasing trip time.