Improved Horizontal Well Delivery Using Advanced Geosteering Technology – The Ogini Field Example

Abstract

Over the years horizontal wells have been drilled using the conventional approach. Failure to drill and place the horizontal drain section optimally was becoming a common occurrence especially in a thin reservoir. The search for processes and procedure to mitigate this failure led to the creation of Well Placement (Geosteering) Process. This process was defined (Rogger Griffit 2009) as "The planned interactive placement of the well-bore using geological criteria and real-time measurements". Using geological criteria in real time requires technology capable of adequately delineating the structure and at the same time providing Petrophysical properties of the reservoir in real time. These needs led to development of key Logging While Drilling (LWD) technologies for high angle and horizontal wells. Over the years, the Geosteering methods have evolved based on available LWD technologies. These methods have been classified as (i) Reactive (Basic log correlation), (ii) Proactive (Distance to Boundary) and (iii) Strategic Reservoir mapping). The objective of this paper is to demonstrate how technologies were utilized in Ogini campaign to optimally position the production section of the wells close to the reservoir top, so as to delay onset of water, reduce intervention cost and to increase ultimate recovery. To achieve these objectives despite high risks due to structure and stratigraphy, two well placement methods / technologies were deployed in the landing and within the production section of the reservoir. Real Time Image/dip technology was utilized in the landing section to aid the landing while monitoring the apparent formation dip and a Multilayer Distance –to-Boundary technology (PeriScopeHD*) was used to optimally position 5 horizontal wells close to the tops of each of the target reservoirs in Ogini field.