Shallow Gas Drilling in North Safaniya, Saudi Arabia: Challenges, Lessons Learned Recommendations

摘要

Safaniya Field is the largest offshore oil field in the world. This field was discovered in 1951 and is located in the Saudi section of the Arabian Gulf. In recent years the importance of Safaniya field has increased due to oil demand and therefore the drilling of new wells has also risen. This field has been divided into three parts: North, Center and South. In the Northern section of this Field, shallow gas formations present a major concern for drilling operation. This gas flow from the shallow formation carries with it high volumes of abrasive sand production of varying sizes from small particles to boulders. This gas has also shown a tendency to bubble through the sea floor, which may result in the formation under the platform or the jacks of the offshore rig to subside and thus taking the risk of a catastrophe that will result in losses in facilities and life. Other challenges include gas migration in the annulus due to reduction in the hydrostatic pressure (insufficient mud weight, mud losses . . .etc.) or bad cement isolation of the annulus between the casing and the open hole that will cause channeling in the cement. This paper describes the challenges encountered in North Safaniya field. In addition, the paper will discuss the lessons learned and the best practices that have been applied. Finally the paper gives recommendations for minimizing and preventing future challenges to arise which include changing the casing design to a more optimum option that will provide more secure isolation of the troublesome formation.