Deepwater Horizontal Openhole Gravel Packing in Marlim Sul Field, Campos Basin, Brazil - Completion Project Learning Curve and Optimization

Abstract

Abstract Most of deepwater Campos Basin reservoirs, offshore Brazil, have unconsolidated formations that require sand control. Openhole gravel packing has proven to be the effective completion method of choice. The main objectives were to achieve low damage ratios, maximize completion efficiencies and reduce completion cycle times. The project was conducted in one of the largest deepwater offshore field in Brazil, Marlim Sul. This paper describes the learning curve and completion optimization obtained during planning, execution, and post job analysis of six horizontal wells campaign with five water injectors and one oil producer. A combination of integrated service lines and experienced personnel were important to achieve excellent injectivity and productivity ratios. Several key operations from drilling to completion contributed to successfully complete these wells: openhole stability, drilling practices, drill-in fluids, wellbore clean-up, filtration, completion fluids, completion tools, sand control, gravel pack software simulator and job execution. The efficiency of the service company was measured with a system of penalties and rewards allowing the operator to monitor and measure the progress of the learning curve on completion. As final result, the partnership between operator and service companies contributed to more economic completion costs by reducing completion time, and improving well performance. Introduction Economic development of deepwater projects demands a minimum number of wells to effectively drain the reservoir. Due to the high cost of deepwater subsea environment, wellbore intervention must be minimized and completion life sufficient to achieve depletion of the reservoir. Typical for the Campos Basin, the Marlim Sul reservoir is a Tertiary unconsolidated sandstone, particularly within the Oligocene and the Eocene ages, without strong water drive. It is a heavy oil reservoir (API 17–24), with 32% porosity, and 2000 mD permeability. Due to the need for high-rate injection to maintain reservoir pressure, and since high-rate producers are needed for economic development, Petrobras decided to develop Marlim Sul and several of the other fields in the Campos Basin with a series of horizontal producers and horizontal injectors. [1] Marlim Sul is a giant field located offshore Rio de Janeiro State, Campos Basin, Brazil (Fig. 1). The field was discovered on December 1987 and it has been under development since 1994. It contains 1.47 billion BOE of proved reserves and additional 1.15 billion BOE of probable reserves. Laying in 2,625 to 8,530 feet (800 to 2600 meters) water depths, the field contains 14 reservoir blocks in a 600 square kilometers area. To lessen risks, Petrobras decided to develop the field in four modules. The wells mentioned on this paper are part of Marlim Sul, Module 1, with 35 wells in total (21 producers and 14 injectors). [2]