Interventionless Monobore Technology Used To Successfully Complete Challenging Offshore Horizontal Gas-Injection Wells (2005)

Abstract Elf Petroleum Nigeria Limited (E.P.N.L.), a subsidiary of Total Exploration and Production, is in the process of developing the Amenam/Kpono oil field. The field straddles the boundaries of OML 99 and OML 70 of the Nigerian Continental Shelf in the eastern part of the offshore Niger delta, in an average water depth of 120 ft. The field is located at about 22 miles to the south of the nearest coast line and 20 miles from the Odudu field. The field development was extremely challenging because of the following conditions:Deep reservoir targets (11,739 to 18,000 ft TVD/SL)High temperatures (130 to 150 degree Celsius)High pressures (370 to 500 bar)High-reach departures of up to 2 miles in certain wellbores, giving rise to highly deviated and deep wells (up to 18,000 ft MD/RT)Reservoir fluid containing 3% by weight paraffinReservoir fluid containing 3% carbon dioxide contentCritical reservoir fluids (bubble point pressure is very close to the reservoir pressure in the main reservoir), which would require early and efficient pressure support for the reservoir In order to deliver wells under the challenging environment and ensure field-life production as well as economic feasibility, much emphasis had to be placed on completions optimization. Hence, completion technology was taken beyond the conventional limits and an innovative, reliable, and cost effective approach was developed. To do this, an especially close cooperative effort by all service personnel, the manufacturing and engineering company, and the operator was needed to integrate the required technologies. This paper will discuss the well completion designs, material selection, manufacturing, preparation, execution and evaluation of the Amenam/Kpono well completions and will focus on how new technologies (reservoir drilling fluid, fluid spring-operated valve, gravel-pack packer, tubing-tester flapper valve, production packer, permanent gauge, etc) were integrated to satisfy all well needs, and especially, those of the challenging horizontal gas injectors. The technologies chosen increased completion efficiency, improved safety performance, and reduced rig time by at least 50 hours per well. Introduction The first phase of the field development was for levels R4; R9, R10 and R11 in the Western and Central parts of the field. Two drilling platforms, AMD1 and AMD2, were installed 345 feet apart and were connected to a production platform (AMP1).Fig. 1 shows the field layout. The development involves the drilling and completion of 34 wells, of which 18 are oil producers, 5 are gas injectors and 11 are water injectors. At the R4 reservoir level, gas injectors are required for total pressure maintenance from the start of the production since the bubble point pressure is close to the reservoir pressure. Thus, gas injection is as important as oil production at this reservoir level. A primary target in the developmental plan was to use enhanced completion equipment to reduce operational risks while completing as quickly as possible. Hence, a monobore completion design with interventionless technology was chosen.