Dual-Zone, Horizontal Internal Gravel-Pack Completion

Abstract

SPE Members Abstract NERCO Oil and Gas, Inc. successfully drilled and gravel packed an extended reach horizontal well from a production platform located in Eugene Island Block 371 to a bottom hole location in offset Eugene Island Block 370 in the Gulf of Mexico in May, 1991. (Refer to Fugures 1 and 2). The well was drilled to a measured depth of 8958 feet and true vertical depth of 3137 feet with a horizontal displacement of 7358 feet. The maximum well deviation was 90.75 with 86 deviation through the completion interval. (Refer to Figures 3 and 4). The total producing interval length of 725 feet (Refer to Figure 5) was divided into two shorter intervals with an isolation interval for two reasons. First, this would improve the opportunity for successfully gravel packing the shorter intervals. And second, the isolation interval in combination with a shale barrier in the reservoir would allow for an economical plugback of the lower interval should the reservoir prove to have a water drive mechanism. The initial well test following the completion indicates that the well was successfully gravel packed; however, the platform is currently installing oil handling facilities, mid future production will determine the ultimate success of the completion techniques employed on this horizontal well. This paper will discuss the completion equipment and procedural design criteria and consideration unique to this case study. In addition, operational results and post appraisal analysis of the completion will be described. The methods outlined in this case study may be applied to highly deviated or horizontal gravel packed completions in unconsolidated sandstone formations. Introduction This extended reach horizontal well was drilled to deplete the TA-1B Sand located in Eugene Island Block 370 from an existing production platform located in Eugene Island Block 371. The TA-1B Sand is a Trimosina A (Upper Pleistocene) outer shelf oil sand. Well B-11 penetrates this sand off the northeast flank of a piercement salt dome upthrown of a large radial fault. The Eugene Island 371 platform was set in November, 1987 and was placed on production in August, 1989. This original facility did not contain the capability to handle oil production. A semi-submersible tender assisted platform rig was moved in for additional field development in September, 1990. The extended reach well B-11 was drilled along with additional conventional development wells to identify reserves and justify the expense of placing oil handling facilities on the platform. The completion design was selected to effectively deplete the oil reserves from the initial completion and minimize the potential of remedial workover operations since a workover in this 420 ft. water depth would require the mobilization of an expensive platform rig. P. 805^