The Horizontal Open Hole Gravel Pack (HOHGP) is the preferred completion method employed in Campos and Espirito Santo basins, offshore Brazil. To pack the well, the proppant is pumped such that the alpha wave is propagated from the heel to the toe of the well and the beta wave then propagates from the toe to the heel. During the alpha and beta waves, the carrier fluid is diverted into and must travel through the narrow annulus between the screen base-pipe and wash-pipe to the toe, where the perforated base pipe is located. This diversion raises the friction pressure significantly. When pumping the beta wave, the friction rises even more because the fluid must travel through the gravel placed during the alpha wave before it can flow through the screen.
The surface pressure required to overcome this high friction pressure can reach or exceed the formation fracture pressure, resulting in early termination of the gravel pack placement due to severe fluid leakoff to the formation. Some solutions are available, but the preferred method of dealing with pressure increases when performing HOHGP offshore Brazil is the ultra-lightweight (ULW) proppants and BOP open (return through the flow line). However, in some cases when the extended horizontal section is associated with a low fracture gradient and washed out zones, the pumping window expansion provided by ULW proppants and BOP open can be still not enough to perform the job comfortably. In such scenario a friction pressure reducer (FPR) was introduced to avoid pressure increases while pumping the gravel pack. The FPR can also minimize friction pressure increases in wells packed using intermediate-density ceramic gravels.
This paper describes 3 successful case histories of circulation tests and HOHGP performed with FPR added to the completion fluid. The focuses are the challenges faced, lessons learned and advantages of using the FPR to extend the safe pumping window.