Abstract

Recent activity in developing the heavy oil reserves of the Orinoco belt has required that operators there utilize cutting edge oil field technologies. The latest in pumping technology and horizontal, multi-lateral well completions are being employed and enhanced. Additionally, operators are looking at new approaches to collect and evaluate well and reservoir data. Coiled tubing is also being used to help with some of the well performance issues.

To optimize the performance of long, and/or multi-branch horizontal wells, post drilling clean-up is very important. Historically, this issue has often been overlooked or dealt with ineffectively. Not only is this step important for the resulting production performance, an effective system for accomplishing this can have additional benefits for the downstream facilities during start-up.

The zones of interest in the Orinoco belt are typically poorly consolidated sands, requiring some form of retaining completion. As slotted liners are most common, an effective method of removing solids from inside the slotted liner may also become a requirement.

This paper will discuss the technology of combining concentric coiled tubing with a jet pump to be able to do both the post drilling fluid clean-up and sand removal operations. It will detail the type of equipment used in this application. The paper will also go into specifics of the need for the service in this operation and the corresponding results. Future developments for this technology will also be covered.

Introduction

Petrozuata C.A. is the operator of a property in Eastern Venezuela's Orinoco belt located just East of San Diego de Cabrutica. This field development is part of a large project incorporating a pipeline network to a 120,000 bopd heavy oil upgrader facility at the coast near Barcelona. Production schedules and targets are all interdependent in order for the project to be a success. Balancing the drilling and completions program with the overall project requirements, the operator has had to adapt the project to cope with the ramping production schedule.

Early on, a need to improve well clean-up after drilling was identified. Concerns of potentially reduced well productivity due to extended exposure times (1–6 months) to a well bore storage fluid (WBSF) prompted a need for cleanup prior to the facilities being ready to start production. A relatively new coiled tubing service was employed to address these issues. Previously only implemented in Canada, a system that utilizes concentric coiled tubing with a downhole jet pump was brought in for the clean-up operations. For this well vacuuming system, a 2,500 m (8,200 ft) string of 31.8 mm (1.25") CT inside of 60.3 mm (2.375") CT is used to both, power a specialized jet pump tool and take returns to surface.

A program of well cleaning using this technology was implemented and continues to be used to remove the drilling fluid (DIF) and well bore storage fluid (WBSF). Additionally, this process minimizes the fluid processing issues typically faced by the production facility during conventional well clean-up periods.

Field History

Petrozuata C.A. is a Venezuelan joint venture company that was registered in March 1996 by Conoco Orinoco Inc. and PDVSA (Formerly Maraven S.A.), an affiliate of Petroleos de Venezuela S.A. The Joint Venture has a 35 year operating life and will require the drilling of over 500 horizontal wells that recover 1.5–2 billion barrels of extra heavy oil during that period. Construction activities commenced in January 1997.

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