The Saudi Arabian Oil Company (Saudi Aramco) operates one of the principal high profile extended reach drilling (ERD) projects in the world. This is accomplished through the development of a sizable number of horizontal wells categorized according to the total depth. Wells with the shortest vertical displacement have been significantly optimized during the project execution thereby reducing the room for enhancement. The drilling engineering team conducted a comprehensive evaluation of the existing casing scheme and problematics along the M field. A new approach was devised to redesign wells with a total depth up to 17,600 ft. The aim was to achieve a substantial improvement in drilling performance and potential savings for the remainder of the project.
ML-1 and MO-1 were selected as candidates to implement the novel alternative; both drilled from different platforms where several wells have been previously completed using the standard design. Drilling troubles, such as loss of circulation and hole instability, occurred during the execution of such wells leading to major lost time. The solution comprised the optimization of the well trajectory, slim-down the upper hole sections and combine the lower ones, drill longer intervals and set casings deeper to cover problematic zones without compromising the well integrity. The detailed engineering study included a probabilistic analysis to evaluate the economic viability of the landmark application.
Two wells were successfully drilled and completed applying the downsizing strategy. The impact of anticipated challenging events in both 12 1/4-in and 8 1/2-in holes was decreased as a result of the new design. The implemented preventive plans led to a rapid elimination of encountered challenges. This optimization produced a combined 27% reduction in drilling time, and minimal non-productive time (NPT) with associated global cost savings of 39% compared to a large hole string design.
Finally, this new approach in a still ongoing project along with the feasibility of extending it to other areas will lead to potential improvement in well delivery and operating cost.
Muñoz, German (Saudi Aramco) | Dhafeeri, Bader (Saudi Aramco) | Saggaf, Hatem (Saudi Aramco) | Shaaban, Hossam (Schlumberger Oilfield Services) | Herrera, Delimar C. (Schlumberger Oilfield Services) | Osman, Ahmed (Schlumberger Oilfield Services) | Otaremwa, Locus (Schlumberger Oilfield Services)
To access the reservoir in a large Saudi Arabian development field, the operator is required to drill an intermediate 5,000 ft to 6,000 ft directional hole section with dogleg severity (DLS) varying from 2.5°/100 ft to 3°/100 ft. The commonly drilled 12¼-in. borehole crosses several interbedded formations comprised of limestone, shale and sands, and it is associated to a variety of hole problems, which present repeatedly in the offset wells. The main objective for the operator was to mitigate the problematic by defining alternative and suited drilling technologies. Among them, Saudi Aramco found that the recent developments in the directional casing while drilling (DCwD) technology may well provide an effective method for diminishing the associated nonproductive time (NPT).
The drilling engineering team conducted an extensive evaluation of the problems across this section, including wellbore stability, water flow, and loss of circulation; tight hole/stuck pipe incidents, severe bit/stabilizer wear while drilling abrasive sands. After a promising technical and engineering evaluation, followed by a detailed risk assessment aiming to determine the potential of the application, the selected well was planned and executed using the DCwD service.
This paper outlines the process carried out during all stages through the final deployment of the first 9?-in. DCwD application in Saudi Arabia, and how it successfully aided in achieving the goals by reducing the impact of some of the problems experienced while drilling the same section in previous wells in the field. Likewise, the information provided will serve as a starting point for the design and construction of subsequent wells leading to further improvement in drilling performance. Best practices and lessons learned from this implementation are expected to become a model and the know-how transferred to other areas where comparable drilling events occur.
The technological benefits have been recognized by the operator and this application reestablished DCwD as a viable technology to address a number of challenges common in many of the Saudi Arabian oil and gas fields.