Ultralightweight Proppants for Long Horizontal Gravel Packs
- Dennis Denney (JPT Senior Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- October 2012
- Document Type
- Journal Paper
- 152 - 156
- 2012. Society of Petroleum Engineers
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- 117 since 2007
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This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 150581, "Ultralightweight Proppants: Best Practices for Long Horizontal Gravel Packs Offshore Brazil," by A.T. Jardim Neto, F.G.M. Prata, and J.R. Gomez, Baker Hughes, and C.A. Pedroso, SPE, M.O. Martins, and D.N. Silva, SPE, Petrobras, prepared for the 2012 North Africa Technical Conference and Exhibition, Cairo, 20-22 February. The paper has not been peer reviewed.
Operators developing and producing reservoirs with deepwater and ultradeepwater wells are pushing technical limits with horizontal extension. Deepwater wells completed in unconsolidated formations usually have low fracture gradients, severe-leakoff zones, or significant washouts. Long horizontal open holes may become technically difficult or economically unfeasible to gravel pack by use of conventional fluids and gravels. Use of ultralightweight proppants (ULWPs) has enabled gravel packing in these longer horizontal open holes. The reduced gravel density allows a significant reduction in pumping rate to avoid fracturing the formation, minimize fluid losses, and eliminate the risk of premature screenout because of excessive gravel settling.
Horizontal openhole gravel-pack (HOHGP) completions are preferred by many operators, especially in permeable unconsolidated formations. Offshore Brazil, especially in the Campos and Espirito Santo basins, HOHGP completions are used to develop post-salt reservoirs. The most common gravels used in the early wells were natural gravels and conventional ceramics. The particle densities (2.65 to 2.73 g/cm3) caused much difficulty with proppant transport, hence an increased dune height that could lead to premature screenout at low pumping rates. A lower-density proppant would be easier to transport with unviscosified fluids such as completion brines, thus allowing the use of reduced pumping rates to circulate proppant at the bottom of the screen and pack the entire horizontal open hole successfully. Two types of ULWPs have been used for this purpose, one with a specific gravity of 1.25 and one with specific gravity ranging from 1.75 to 1.90 (ULWP-1.25 and ULWP-1.75, respectively).
Well Configuration and Completion
Most fields in the Campos and Espirito Santo basins are developed with a minimum number of wells, some being extended-reach wells. To reduce the number of casing strings, a slender-well design often is used. The horizontal open hole is drilled at 90° to final depth with an 8½- or 9½-in. bit and drill-in fluid. After the final horizontal extension is reached, the drill-in fluid is replaced with completion brine. Then, the completion assembly is run into the well.
The completion equipment comprises an isolation packer and 13 Cr premium screens. The gravel-pack operation is performed with a special horizontal tool system that allows gravel packing and stimulation of the horizontal well in a single trip.
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