Low-Cost Alternative for Remedial Sand Control Application

Abstract

Summary During mid-1992, a remedial workover program was implemented offshore within the Gulf of Mexico on low-rate marginal-reserve sand-producing wellbores. A process called through-tubing gravel packing (TTGP) was used on five offshore wells and one U.S. gulf coast land well. This technique involved the placement of ceramic beads and prepacked screen within existing completions with coiled tubing (CT) to eliminate sand production (Fig. 1). The basic steps of TTGP consist of wellbore cleanup, CT counter correlation, injectivity testing, running a dummy assembly, ceramic bead placement, prepacked screen placement, and installation of an isolation device. The TTGP method demonstrated versatility in adapting to individual well conditions. This remedial sand control technique was successfully applied in highly deviated wellbores, in the upper zones of a dual completion, and within existing gravel packs for screen repair. TTGP's were performed offshore in as little as 5 days with a CT unit at a cost of $63,500. Five wells were mechanically successful, but only three wells were considered economic successes. Simple individual payouts for the wells ranged from 46 to 77 days, with an associated production gain of 2,020 Mcf/D and 39 BOPD. Economic success improved over time as mechanical success increased. Project incremental production was 1,070 Mcf/D and 38 BOPD. The total cost of the project was $571,807. The average offshore workover cost was $ 110,761, and the workover cost for the onshore well was $18,000. Throughout the implementation of this program, mechanical problems were addressed that led to improvements in subsequent workover programs. This paper details the TTGP program and recommends mechanical improvements for performing future through-tubing gravel packs.