An Overview of More than One-Hundred-Twenty Horizontal Gravel Packing Operations In Campos Basin

Abstract

This paper presents the lessons learned by Petrobras after performing a total of 124 horizontal open hole gravel-packing operations in Campos Basin. The authors intend to describe how the industry-provided standard gravel packing procedures had to be continuously improved and/or adapted to meet Campos basin requirements, such as: -low fracture gradients, - long intervals to be packed, -pumping jobs performed from floating rigs and -the need to sustain high production levels - or high injection rates - to justify the huge amount of investments associated to ultra-deepwater production enterprises. It is also described the main technology innovations that were incorporated to our completion projects in the last few years. Among these innovations one can find: - modified standard tools to reduce pumping pressures, - external casing packers, -inflatable straddle packer to divert post-gravel treatments, -pressure reducer valves, - - flowline's flow meter and shunt tubes. Formation damage in gravel packing operations is addressed on a comprehensive basis, encompassing the following items: -drill-in fluid rheological specifications, - pre-job wellbore cleanup procedures, - optimizing drill-in-fluids mud cake removal, -job design and execution, gravel carrier fluids filtration requirements, -postjob remedial treatments and diversion techniques as well. Introduction The most prolific reservoirs in Campos Basin are Tertiary and upper Cretaceous unconsolidated turbidites that require a sand control/exclusion method either to maximize sand-free production or to manage massive water injection to provide reservoir pressure maintenance. Therefore, from the firstdiscovered oifields in shallow waters to the large ones more recently discovered in deep- and ultra-deepwaters scenarios in Campos Basin, emphasis has been placed on total sand exclusion well completion techniques. Propelled by the ever-growing complexity of Campos Basin wells, as we moved from shallow to ultra-deepwaters, sand control technology innovations were incorporated to our projects on a continouos basis, such as:–cased-well frac pack, -chemical consolidation (one single case),–stand-alone completions (sintered metal mesh and premium screens),–highly-deviated- and horizontal-open-hole gravel packing and very recently expandable screens (ES). Currently, gravel pack is the most popular sand exclusion technique used in Campos Basin. From the early 1980's to circa 1995 this technique was applied to cased-wells only1. Nevertheless, huge production impairments were a common place due to non-optimized cased-hole gravel packing techniques. Typically, PI reductions of up to 75 % were recurrent at that time. A series of improvements to the existing cased-hole gravel packing placement techniques was subsequently made. As an outcome of such actions a fair reduction of the pressure drop across the gravel ended up being achieved. However, the magnitude of the productivity index (PI) of the gravel packed cased-wells, hovering around 8,8 bbl/psi, was still a short-coming for the economical feasibility of these shallow waters projects and for the deepand ultra-deepwaters ones as well. As an alternative completion technique to cased gravel packed wells, the frac-pack technique was introduced early in the 1990's in Campos Basin.2 The application of this technique to vertical- and deviated- cased-wells in Marlim field was a step further towards a better sand face completion.

The 200th Horizontal Openhole Gravel-Packing Operation in Campos Basin: A Milestone in the History of Petrobras Completion Practices in Ultradeep Waters

“…Only 3 years have passed since our 120 th horizontal open-hole well had been gravel packed in CB. 3 As of February 2007, more than 200 horizontal open-hole wells have been successfully completed with gravel packing in CB. An average of 26.7 of gravel packing jobs/year in the last 3 years.…”

Designing Multiple Alpha Waves for Openhole Gravel-Pack Operations

“…Since a larger diameter openhole section is exposed (rat-hole), if the flow rate is too low, alpha waves formed may be high enough to block sand passage to the openhole, generating immediately a beta wave in the rat hole. The consequence is that the pressure at the last casing shoe will immediately increase and the operation will have to be aborted without packing the openhole (Marques et al 3 ).…”