Customizing Drill-In Fluid for Peregrino Project in Brazil: Laboratory Development and Field Experience

Abstract

This paper describes the design and qualification process used to select a reservoir drill-in fluid (RDF) for the Peregrino field offshore Brazil, and the successful application of this fluid. The Peregrino field is located east of Rio de Janeiro in the southwest Campos Basin area. Approximately 2.3 billion barrels of oil are in place in the Peregrino reservoir. The productive sands in this variable reservoir typically exhibit permeabilities between 6 and 15 Darcy, and are unconsolidated with interbedded shales. Peregrino crude oil is heavy (13API) and viscous. The estimated recoverable volume of crude oil is 300 million to 600 million barrels. The selected fluid, a NaCl brine-weighted water-based mud employing KCl and Glycol additions for shale stabilization, was used to drill the first wells at Peregrino. Penetration rates were high and zero non-productive time occurred. To achieve this drilling performance in the high permeability, unconsolidated, heavy oil reservoir, an extensive fluid selection process was performed to optimize the drill in fluid for maximum well productivity. Key test results reviewed in this paper include: Bridging solids optimization, lubrication, shale inhibition, fluids compatibility, filtercake lift off and backflow performance, breaker fluids and formation damage The reservoir sections of the wells were successfully drilled, open-hole-completed with sand screens and gravel packed with 100% efficiency.

Experimental approach for assessing filter-cake removability derived from reservoir drill-in fluids

“…The depth of invasion must be evaluated in parallel in order to understand the damage caused. In some agreement with these findings, lift-off pressure evaluations were also presented by Han et al (2012). The focus was on selecting the optimum reservoir drill-in fluid for an open-hole gravel pack reservoir completion.…”

Formation Damage Avoidance by Reducing Invasion with Sodium Silicate-Modified Water-Based Drilling Fluid

“…Han et al [24] formulated sodium chloride (NaCl) brine-based drill-in fluid with 3.5% potassium chloride (KCl) and 3% glycol additives to drill four horizontal wells to Peregrino heavy oil field in Brazil. The oil density was 13 API.…”

Long‐ and short‐term effects of smothering and burial by drill cuttings on calcareous algae in a static‐renewal test

“…Rhodoliths are sparsely to densely distributed within a total sampling area of 15 km 2 and are associated with limestone gravel [7]. The Peregrino reservoir is located approximately 2300 m below the seabed in relatively heterogeneous, high-permeability, unconsolidated sands that are interbedded with shales and mudstones [9]. The Peregrino reservoir is located approximately 2300 m below the seabed in relatively heterogeneous, high-permeability, unconsolidated sands that are interbedded with shales and mudstones [9].…”

“…The sparse area is associated with a fine-grain, mobile bottom, and the dense area is associated with a coarse, gravelly bottom [7]. The Peregrino reservoir is located approximately 2300 m below the seabed in relatively heterogeneous, high-permeability, unconsolidated sands that are interbedded with shales and mudstones [9].…”

“…Before disposal, the cuttings are separated from the fluid through sieves of different sizes by gravity [12]. The fluids used in Peregrino were a NaCl/KCl brine-weighted waterbased mud with glycol [9]. Some products used in the drilling activity may adhere to these cuttings, and these products may be toxic to organisms [13].…”