Combination Fracturing/Gravel-Packing Completion Technique on the Amberjack, Mississippi Canyon 109 Field

Abstract

This paper describes a one-step fracturing/gravel-pack (frac-andpack) completion procedure conducted on the BP Exploration Amberjack platform beginning in early 1992. This platform is 35 miles southwest of Venice. LA. The first four completions on this platform had an average positive skin values of 21. The goal of the frac-andpack procedure was to reduce these skins to nearly zero. In total, 24 frac-and-pack operations were performed. Details of the fracture design, pre fracture testing. fracture design and execution, and production response and a continuing optimization program are discussed. The fractures were performed with the screens in place with the gravel pack after the fracturing operation. The treatments were designed for the tip screenout technique 1 ,2 to create wide fractures and to provide proppant loadings exceeding 8 Ibmlft 2 .This paper presents the trend of the declining skin values. along with a discussion of time-dependent skins. The changes in fluids. breakers, and proppants are also presented. The average skin on 14 frac-and-pack completions was 5.3. The average skin on the final eight completions was 0.2. Design and ExecutionIntroduction. The BP Exploration Amberjack Project (Mississippi Canyon Block 109) is 35 miles southeast of Venice. LA. and 18 miles from the Mississippi River delta. The water depth ranges from 850 to 1,500 ftin the block. Acquired in 1983. the field is on the eastern side of the Plio-Pleistocene flexure trend of the Gulf of Mexico.A persistent problem with offshore gravel packs has been the presence of high positive skins measured on transient-pressure tests. Positive skins of 10 to 50 are routinely measured on all but very short intervals using state-of-the-art gravel-packing technology. Our early experience on the Amberjack platform showed a clear trend of higher-than-desired skins. On the first four wells. a viscous slurry prepack was pumped into the perforations. and after cleanout, the screens were run and a water pack was pumped. Studies have shown that using water as the carrier fluid provides a uniform, tight pack. Despite this, high positive skins were still measured.We think that a primary reason for the high skins may be that the prepack techniques currently used may not place sufficient sand in all perforations. A second and potentially more important reason is that the cleanout operation may destroy the hydraulic continuity between the perforations and the packed screens. Fracturing followed by gravel packing provides excellent vertical proppant distribution. This ensures that the connection among the formation, perforation, and packed screen is maintained if the operation is performed in one step. After a thorough review, a decision was reached to implement the frac-and-pack process with the screens in place.The fracturing treatments were performed with the screens in place, the crossover tool in the circulating position. and a closed choke on the annulus. The desired proppant volume is placed at fracture rates followed by an appropriate gravel-pack volu...

Offshore Hydraulic Fracturing Technique

“…The hydraulic fracturing operation appears to stress the near-wellbore formation sand grains so that conventional gravel-pack sand-control sizing criteria do not apply. 7 Gravel-Pack. An excellent annular gravel pack should be obtained from the frac-andpack operation.…”

“…We believe that at least 4.0 Ibm proppant/ ft2 is required in the fracture to provide effective conductivity and to offset embedment of the proppant into these lowmodulus sandstones 7. Most treatments are pumped at injection rates of 8 to 15 bbl/min, with sand concentrations staged from an initial 0.5 Ibm/gal to a final 16.0 Ibm/gal slurry concentration.…”

Frac Packing: Best Practices and Lessons Learned From More Than 600 Operations

“…14-Skin factor with various perforation conditions. (Data were compiled from Hannah et al 1994;Petit et al 1995;Stewart et al 1995;Neumann et al 2002;Ott and Woods 2003;and Pourciau et al 2005.) trips.…”

Designing and Completing High-Rate Oil Producers in a Deepwater Unconsolidated Sand

“…All five completions were fracpacked with screens in place; this is standard BP Amoco practice based on knowledge gained from extensive experience (4)(5)(6)(7) . The perforated intervals varied from 122' to 161' MD and from 94' to 139' TVD.…”