An increasing number of deviated wells are being drilled to maximize production and hydrocarbon recovery in the mature reservoirs of the Gulf of Suez (GoS). Successfully drilling a high-angle well in a tectonically disturbed and structurally complex area like the GoS is very challenging, especially in depleted reservoirs. Selecting the optimal mud weight is absolutely essential. Stress orientation and magnitude also have a major impact on wellbore stability.
The region poses significant drilling challenges that vary widely from reactive shale and salt creep to stress-related instability. From the findings of multiple wellbore stability projects we conducted in the GoS, we review the dominant mechanisms of wellbore instability in the GoS. We provide a summary of the failure mitigation measures and an overview of stress magnitude and orientation in the region, demonstrating how it impacts the knowledge of the most stable drilling direction.
Understanding the main causes of rock failure in the GoS resulted in improved drilling efficiency and reduced drilling costs. We show an example, where a new, nearly horizontal (86º) well was successfully drilled through the Asl formation with less than half a day of non productive time during the entire drilling process.
We conclude that acquisition of new, high-quality data would considerably reduce the uncertainty surrounding drilling complex wells in the area and reduce their cost.
refai, ibrahim Meselh (Schlumberger) | Assal, Anwar Ahmed Maher (Schlumberger) | Fould, Jeremie Cyril (Schlumberger) | O'Rourke, Tim (Saudi Aramco) | Haque, Muhammad Habib (Saudi Aramco) | Sayed Akram, Nawaf Ibrahim
A number of the wells reach there economical production limit and are consequently abandoned or mothballed until viable solutions are available to enhance there production to an economically feasible level. The Hawtah field (see Figure 1) discovered in the late 1980s is located 180 km south of Riyadh, the capital of Saudi Arabia (figure 1).
Hawtah is one of several small fields located along the Hawtah Trend (others are Ghinah, Hazmiyah, Nisalah and Umm Jurf). The Trend runs approximately 30 km east to west and 50 km north to south. Production in Hawtah comes from the Unayzah sandstone and consists of Arabian super light (50° API) sweet crude oil.
Hawtah field is a mature and depleted reservoir, and in order to maintain economical levels of production a combination of several technologies is being applied.
Due to the poor natural production from the vertical cased and perforated completions in Hawtah and little associated gas, electrical submersible pumps (ESPs) have been used in Hawtah to enhance production since early 1990's.
Existing wells are standard 9-5/8?? vertical cased wells with perforations through the thin producing interval with ESP set in the same casing. Due to the low productivity of this type of completion, and high water cut a work-over program was initiated by Saudi Aramco in the late 90s to re-complete these wells as horizontal producers using various sand control techniques.
While converting from vertical, cased and perforated wells to single horizontal producers has helped to improve production, multilateral wells are needed in Hawtah to achieve and maintain economical production rates from these wells. In addition sand control solutions are required to safely deploy several branches off one main vertical well.
This paper will describe the history of the well HWTH-34 and workover's performed during its life span. It will also discuss the latest achievement deploying Saudi's first TAML Level 3 multilateral completion of a tri-lateral well.
Well History - Introduction
HWTH Well No. 34 was drilled to a total depth of 6,662' and completed on 11-03-1991 as a vertical cased and unperforated oil producer in Unayzah reservoir. The well was then suspended with cement plugs and the wellhead blind flanged. The 7" liner was run and cemented from 6661' to 4907' with 100% circulation.
WORKOVER No. 1: was completed on 10-30-93. Cement was drilled out and well cleaned to 6563' (PBTD). The Unayzah reservoir was perforated with 4-1/2" TCP Guns selectively from 6264' to 6392'. The well was completed with a new ESP with bypass assembly ran on 3-1/2" EUE x 4-1/2" VAM tubing.