Abstract

Through-tubing bridge plug (TTBP) water shut-off (WSO) workovers in the October Field have resulted in an average incremental initial production increase of 2500 bopd per job. Average water cut (WC) was reduced from 55% to 16%. Seventy-eight WSO workovers have been completed since December 1991. Technical and economic success approach 90%. Just under $4.8 million dollars has been spent for an average cost of $61,500 per job. Costs paid out in less than two days using a normalized $13 per barrel crude price. Based on results achieved during the past 4.5 years, these WSO workovers establish the October Field as a notable and on-going case history for lower zone water control.

Water production from the October Field has gradually increased during the past decade. As a result, steeper production declines and gas lift operational problems developed. Based on reservoir characteristics, lower zone water was isolated using TTBP's conveyed by way of portable mast electric line units. A dump bailer was used to place a 14 foot cement cap over the TTBP to provide a permanent pressure seal. After a 24-hour shut in cement cure period, wells were almost always returned to production at a significantly higher oil rate and dramatically reduced WC. The cost of a rigless TTBP WSO workover is much less than conventional rig deployed WSO work which averaged over $500,000 per job. Prior to December 1991, rig WSO's were the only method used in the October Field. Hence, rigless WSO workovers have become vital for cost control. Rigless WSO work has also become a useful reservoir management tool for maximizing oil production and minimizing water production thereby conserving reservoir energy and optimizing lift gas.

Introduction

The October Field is located offshore in the Gulf of Suez (GOS) approximately 200 miles southeast of Cairo and 70 miles north of the operating base in Ras Shukheir, Egypt (Figure 1). The October Field area is the largest of seven major producing areas in the GOS operated by the Gulf of Suez Petroleum Company (GUPCO); a joint venture between Amoco Egypt Oil Company and the Egyptian General Petroleum Corporation. Combined GUPCO GOS production averaged 365,000 bopd during early 1996. Gas lift is the most widely used form of artificial lift. Original oil in place (OOIP) for all fields approached 10 billion barrels by 1996.

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