Well Completions in the Beta Field, Offshore California

Abstract

Abstract The heavy oil reservoir in the Beta Field, Offshore California is thick (up to 1200 feet gross), unconsolidated, consists of nine distinct sand intervals, and lies at a shallow depth. In order to economically develop the field from two platforms and be able to waterflood, the development wells must platforms and be able to waterflood, the development wells must (1) be highly deviated with an 'S' shaped profile, (2) have isolated multi-zone completions designed with the capability to selectively inject or produce any combination of zones, and (3) produce virtually sand-free because of the use of electric submersible pumps for artificial lift. pumps for artificial lift. To meet these requirements, new completion techniques were developed. This paper reviews the overall completion sequence starting with primary cementing and zonal isolation, through perforating and perforation cleanup, and finishing with the inside perforating and perforation cleanup, and finishing with the inside casing gravel packing and gravel pack logging. The new techniques have proved expedient and successful, with 40 producing wells containing a total of 152 individual zones completed as of December, 1982. Introduction The Beta Field, located on Federal acreage nine miles offshore Huntington Beach, California (see Figure 1), has been delineated in 1976 and 1977 by eight exploratory wells drilled by Shell and partners and thirteen by Chevron, et al. A structure map of the D sand, and a cross section are shown in Figures 2 and 3 respectively. Water depth-ranges from 220 feet at the northern boundary of Shell's leases to over 1000 feet along the south line. The top of the pay is as shallow as 2700 feet and the lowest oil-water contact has been encountered at 4900 feet subsea. The productive interval is composed of as many as nine separate zones productive interval is composed of as many as nine separate zones with a gross vertical thickness of 1200 feet and is divided in a number of fault blocks. The reservoir rock consists of unconsolidated sand containing heavy oil with gravities ranging from 11 to 19 API. Individual zones have different water levels, and water levels vary in different fault blocks. Two drilling platforms will be required to develop the indicated productive area on 15 acre spacing. Platform Ellen with 80 slots and 30 curves conductors was installed in 1980 in 265 feet of water. Platform Eureka with 60 slots is currently under construction and will be installed in 700 feet of water. A Facilities platform (Elly) to handle the production from both drilling platforms has been installed next to Ellen. Pipeline quality oil is shipped from Elly through a 16-inch diameter 15 mile long line to Long Beach. As of December, 1982, two rigs have drilled 49 wells from Platform Ellen, including 39 producers, 1 gas storage well, 1 disposal well, 1 producer converted to water injection, 1 water source well, and 6 dry holes. Because of the location of the drilling platforms, the shape of the field and the shallow depth of the reservoir, a considerable number of wells have been drilled as highly directional holes with inclinations of up to 75 and hole angle buildups of six degrees per 100 feet. The wells have been completed over most of the per 100 feet. The wells have been completed over most of the productive interval with zonal isolation between individual pay productive interval with zonal isolation between individual pay zones. This type of completion was selected to achieve (1) adequate production rates, (2) uniform drainage of the multiple reservoir production rates, (2) uniform drainage of the multiple reservoir intervals, (3) the ability to control water production and (4) flexibility to inject water into any combination of individual zones. Electric submersible pumps have been selected for artificial lift, which requires virtually sand-free production. After reviewing various options it was concluded that the completion could best be achieved with a number of isolated inside perforated casing gravel packs with wire wrapped screens. However, perforated casing gravel packs with wire wrapped screens. However, to install multiple gravel packs in highly deviated wells with producing intervals up to 1600 feet long, new completion techniques producing intervals up to 1600 feet long, new completion techniques needed to be developed with regard to perforating, perforation washing and multiple zone gravel packing. p. 295