Completion Techniques for Albuskjell, Edda, and Eldfisk Fields

Abstract

Luppens, J.C.; SPE; Phillips Petroleum Co. Summary Since Ekofisk field was discovered more than 10 years ago, approximately 100 development wells have been drilled and completed, with about 50 wells remaining to be drilled. The evolution of the mechanical completion has led to a great emphasis on standardization, simplification, and quality control. The result is a highly reliable, potentially trouble-free completion for deep, highly deviated, high-pressure, high-temperature wells. Introduction The Ekofisk field, located in the Norwegian sector of the North Sea, was discovered by the Phillips Norway Group in Dec. 1969. A temporary test program, Phase 1 of the development program, was implemented in late 1970, program, Phase 1 of the development program, was implemented in late 1970, and four exploratory wells on the structure were re-entered and completed as subsea producers. These subsea wells were connected to production facilities installed on a converted jackup drilling rig and oil was loaded into tankers using single-buoy moorings.Phase 2 was the installation of the permanent drilling and production platforms. These drilling platforms are Ekofisk Alpha, Bravo, and Charlie platforms. These drilling platforms are Ekofisk Alpha, Bravo, and Charlie (2/4 A, B, and C).Phase 3 consists of the drilling platforms West Ekofisk (2/4 D), Tor (2/4 E), and Cod (7/11-A). The 34-in. oil pipeline to Teesside, England, and the 36-in. gas pipeline to Emden, Germany, also were a part of the initial Phase 3 plan. As the Teesside facilities became operational, natural-gas liquids were fed to the oil pipeline and the second part of Phase 3, consisting of five drilling platforms, was implemented. These Phase 3, consisting of five drilling platforms, was implemented. These platforms are Albuskjell Alpha (1/6 A), Albuskjell Foxtrot (2/4 F), Edda platforms are Albuskjell Alpha (1/6 A), Albuskjell Foxtrot (2/4 F), Edda (2/7 C), Eldfisk Alpha (2/7 A), and Eldfisk Bravo (2/7 B). The general layout of the Greater Ekofisk area is illustrated in Fig. 1. The last Of these platforms to come on stream was Edda on Dec. 3, 1979. During Nov. 1979, the greater Ekofisk area produced an average of 501,625 B/D of oil and natural-gas liquids and 1.422 billion cu ft/D of natural gas sales.The Phillips Norway Group consists of Phillips Petroleum Co. Norway, operator, and 36.96% interest; Norske Fina A/S, 30% interest; Norske Agip A/S, 13.04% interest; and the Petronord Group, 20% interest. The Tor field unit consists of the Phillips Norway Group, 75.5% interest, and the Amoco/Noco Group, 24.5% interest. The Albuskjell field unit is made up of Shell and the Phillips Norway Group, each with an initial 50% interest.Sixty-nine wells had been completed when completion operations began on the five platforms encompassing the second part of Phase 3. Several problems with the mechanical completions up to this time resulted in problems with the mechanical completions up to this time resulted in changes being implemented on the Albuskjell, Edda, and Eldfisk wells. Additional problems, especially on Albuskjell, led to further equipment modifications and an installation-technique change after 21 wells had been completed on these platforms. Since that time, eight additional wells have been completed, with another 40 wells presently scheduled for completion. Two initially completed wells on Albuskjell Foxtrot rater were abandoned and only one of these is programmed for replacement, resulting in a total of 67 wells existing or scheduled for the Phase 3, Part 2, platforms. The Completion String A 7-in., 29-lbf/ft N-80 and C-95 buttress string is used for the production casing, with 600 ft of 7 5/8-in., 29.7-lbf/ft N-80 run at the top of the string to provide clearance for running a ported safety-valve nipple. This string usually is set between 10,800 and 11,200 ft TVD. Similar production casing strings have been run on most of the wells in Phases 2 and 3.All completions in the greater Ekofisk area are single-string completions. Based on economic and engineering considerations, a tubing string with premium seals is desirable. When cost, compatibility, and reliable sources were evaluated, VAM connections were selected. Normally, 4 1/2-in., 12.6-lbf/ft L-80 tubing is used. JPT p. 471