Maximizing Opportunities in The Gas Sector by Using Existing Wells and a Fast-Track Development Approach: The Zeta Field Case Study

Abstract

The maturation and development of gas resources has of recent been on the front burner for many Oil & Gas producing countries and companies, mainly due to the drive for more environment friendly fuel and increasing demand for natural gas as a key driver for industrialization and growth. In Nigeria, the situation is not different, with proven reserves of 180 Tcf, but very low figures in production and utilisation of its gas resources, there has been an increased focus and push towards increased development in the natural gas sector. From the inception of oil and gas exploration in the late 1950’s to late 1990’s, most of the focus in the Nigerian Oil and Gas industry has been towards oil development, with little or no focus on gas, which led to the suspension of many exploratory/appraisal gas discoveries in several fields, with no plans of further development. The Zeta field is located in the Niger Delta region of Nigeria, with predominantly gas bearing reservoirs. Together with other nearby fields, it has about 9 Tcf of discovered GIIP. There is no existing infrastructure to process or evacuate the gas. Zeta field currently has four exploration and appraisal wells drilled between 1973 and 1987 and encountered 13 stacked reservoirs with a total expectation GIIP of about 2 Tcf and CIIP of about 100 MMstb. This paper highlights how opportunities in the gas sector has been maximized by deploying an innovative commercial and technical solution to unlock gas resources from a cluster of fields with large gas resource but not close to any evacuation facility. It shows how the existing exploration/appraisal wells has been planned for re-entry and side-track, to ensure a fast-tracked development of five Ready-To-Go (with no technically exploitable oil rim) reservoirs in the field. It also highlights how scalable reservoir models have been used in the development of the five reservoirs ensuring that the target onstream date is met.