The Development of Innovative Solutions Through a New Operator/Contractor Relationship
Authors: Kusaka K. , Patel D. , Klein B. 
Published: December 2007

The Andrew Field in the UKCS, operated by BP Exploration, is under development with horizontal oil producers with typically 1300-m long horizontal sections completed with a cemented liner. In the early stages of the planning, it was identified that the productivity of each well was one of the most important factors for the overall project economics. The well completion and perforation design used has a major impact on the well productivity.

Although perforating extensive horizontal intervals lends itself to tubing-conveyed perforation (TCP), the benefits of underbalance perforation may be reduced if the well has to be killed to pull the guns out of the hole after the job. Commercially available deployment methods did not fulfill the project goals; therefore, a new engineering solution for perforating was required.

One of the key elements of this new perforating method is a newly developed large-bore mechanical valve, the FIV, Formation Isolation Valve tool. The FIV tool has contributed not only to protecting well productivity, but also to reducing operating time and the cost of perforation; i.e., the first oil was achieved earlier with substantial cost savings.

The FIV tool development was much shorter compared with the traditional product development cycle. This was made possible by establishing a new operator/contractor relationship through an alliance contract. In this paper, we explain how the integration of operator and contractor project teams and the setting of common goals have changed the way service company traditionally develop new technologies. The planning, integration of the project team, fit-for-purpose equipment, innovative alliance contract and risk sharing will be discussed through the case study of the Andrew project.

Introduction

The Andrew field, a four-way dip-closed structure with a 58-m oil column between the gas cap and acquifer is located approximately 50 km northeast of the BP Exploration's Forties field. Andrew field was discovered in 1974, but development drilling did not start until September 1995. The reservoir cross section is illustrated on Figure 1. The original development scheme with vertical/semivertical wells required drilling 18 wells, which made the economics of the project unattractive. However, with the advance of horizontal well technologies in recent years, the project became economically feasible. Currently, it is envisaged that the Andrew field will be developed with only 10 horizontal wells, typically with a 1300-m reservoir section and completed with a cemented liner.

Early studies suggested that the productivity of each well, delaying gas/water breakthrough by uniformly draining from the reservoir and the ability to control undesired gas/water, had large impacts on the overall economics of the Andrew field development. Therefore, special emphasis was put on perforating design because perforation has a major impact on well productivity and reservoir drainage as the final key step in the well completion.

Several innovative technologies were applied to Andrew perforating to meet challenges. One of these challenges was the world's first underbalanced single-trip, no-kill perforating of long horizontal wells using a hydraulic workover unit and the FIV tool.

The FIV tool is a large-bore mechanical ball valve that is set in a completion string below the production packer and used as a lubricating valve when the guns are retrieved. The detailed description of the valve and operating sequence can be found in several recent papers. P. 493^