Reducing NPT (Non-Productive Time) in Deepwater Subsea High Rate Wells - A Field Case History
Authors: Tibiletti Max , Mohamed Omar , Toubar El-Metwally 
Published: October 2008

This paper describes the evaluation process employed to reduce non-productive time in a deepwater application. It will delve into the completion selection process, the actual operations, and the continuous improvement process during the completion.

The subject field for this paper is Phase 1 of the Scarab/Saffron development in the offshore West Delta Deep Marine Concession (WDDM). This field was characterized by a number a firsts, including:the first deepwater completion operations in the WDDM;the first advanced subsea completion; andthe first in a long series of additional, more complex deepwater completions.

Although first in the area, planning and execution of the completion incorporated many experiences from similar completions and utilized/enhanced those learnings. This paper captures how previous lessons learned from different environments can be incorporated to an existing development to mitigate non productive time.

The completion selection process included such factors as sand control, fluid loss control, operational risk and reliability. Open hole gravel pack technique was selected based on its ability to provide excellent sand control, high productivity, and sustained well life.

The development consisted of eight vertical subsea wells completed over a period of seven months. During that time, lessons were learned and were employed to further reduce the non-productive time. Such quick and thorough evaluation of the completion process and resulting implementation within the existing program culminated in the last well being completed in less than 15 days, well under the original budgeted time of 36 days.

Introduction

The Scarab/Saffron fields are located in the West Delta Deep Marine Concession (WDDM) in water depths ranging from 400 to 650 meters and situated some 90 km offshore Nile Delta (Fig. 1). The Burullus Gas Company, a sister company of the Rashid Petroleum Company (Rashpetco), operates the West Delta Deep Marine Concession on behalf of the Egyptian Government oil and gas industry.

The Scarab/Saffron development consisted of eight vertical sub-sea wells that were drilled and completed to depths ranging from 1,800 to 2,100 meters TVDSS. It is the first deepwater offshore completion operation in the WDDM and the first advanced subsea completion conducted in Egypt. In addition, the processes and procedures employed would be used as a template for subsequent operations in the WDDM.

Since this operation represented a first in the various completion aspects, a considerable amount of time was spent optimizing the well design. More than two years before commencement of operations, Burullus Gas began working with various vendors to evaluate the completion design options, production performance, and operational requirements.

The Scarab/Saffron development presented a number of challenges including: operating costs approaching US$200,000/day; high intervention costs driving the need for interventionless completions; sustaining high well productivity, equipment reliability and standardization; the need for sand control; and safety.

Completion operations have shown a noteworthy learning curve and best in class performance resulting in the final subsea completion being run in under 15 days, resulting in a reported savings of over $20 million in the overall drilling and completion costs against the overall project (Fig. 2).