Lessons Learned from a Hundred Frac Packs in the Campos Basin

TLDR

Campos Basin reservoirs are clean tertiary sandstones with very high permeability, requiring high‑conductivity fractures for low‑skin completions, and since 1996 challenges such as leak‑off control and rock‑mechanics‑based design have been addressed. The paper reviews state‑of‑the‑art frac‑packing practices derived from over a hundred operations in the Campos Basin, offshore Brazil. Frac‑pack performance is achieved through aggressive tip‑screen‑out techniques, minifrac analysis, careful fluid and proppant selection, calibration tests, and real‑time design and BHTP data collection, accounting for factors such as spurt loss, fluid efficiency, stress anisotropy, and stress contrast. Frac pack is unequivocally superior to conventional gravel pack.

Abstract

Abstract This paper presents the state of the art in frac packing learned from more than a hundred operations performed in the Campos Basin, offshore Brazil. Many reservoirs in the Campos Basin are clean tertiary age sandstones, very unconsolidated, with high to ultrahigh permeability. In this scenario, in order to get low skin completions, high conductivity fractures must be created. These can only be obtained with the use of aggressive tip screen out (TSO) techniques. For these reasons, no questions remain about the superiority of frac pack when compared with conventional gravel pack. Since February 1996, when the first frac pack job was performed, many challenges have been overcome, especially those related to handling leak off in very high permeability and the correct use of rock mechanics properties for proper frac pack design. These include minifrac analysis for very low efficiency fracturing fluids, the use or not of spurt loss, how fracturing fluid efficiency is affected by prior calibration tests, horizontal stress anisotropy for unconsolidated sands, stress contrast for layered sandstone's, etc. Others lessons have been learned such as: the need for high quality fluid, high quality proppant, good proppant placement, as well as calibration tests, real time design and BHTP data collection for all jobs (from electronic gauges or from live annulus).