Cemented and Cased Hole Multistage Stimulation Technology Development and Field Wide Implementation in a North Sea Chalk Oilfield

Abstract

Abstract In close cooperation with a major international operating company, the service company specialising in completion Sliding Sleeve technology has developed a completion system that facilitates efficient Multistage Stimulation, and allows production management and re-fracing/stimulation of individual zones. The field wide implementation of the system has yielded a step change for the operator in terms of operational efficiencies, production management and re-fracing/intervention capabilities. This paper will present the successful technology implementation on a giant North Sea chalk oilfield. A collaborative approach was taken, with close dialogue between the operating company and the service company, in defining the system requirements for the desired completion and stimulation methodology. Design criteria for tools were developed, validation testing and product qualification of the individual components followed by field trials were conducted. Throughout the process, a detailed focus on job preparation, execution and integration with the overall well construction and stimulation process was essential in ensuring the successful technology implementation. This paper will discuss the technology development and implementation project resulting in two reservoir completion systems being installed in more than 27 wells in the same field. One of the systems is a cemented multi entry ball drop system, the other is a cased hole single entry ball drop system. The process of technology implementation with focus on various case histories is presented. The installation and operational sequences and challenges that have been encountered will also be discussed. The paper will provide insight into how these systems provide unique benefits to the operator during the following phases of the wells life: Completion - Sleeve design and qualification grade significantly reduces completion steps and cost for the operator.Stimulation - stimulation efficiency provides dramatically reduced opex compared to alternative methods.Production Management - the system has built in features that allow management of unwanted production by cost efficient intervention method.Re-Stimulation - controlled re-stimulation of individual zones is possible. This paper will present the collaborative development and field wide implementation of cemented and uncemented Multistage Stimulation Technology that has rapidly gained operator acceptance and realized significant cost savings to the operator. Both the technology and methodology used and the results achieved should be of interest to the petroleum industry.