The Success of Drilling Long Departure Wells with Light/Slim Casing Design in United Arab Emirates Onshore Field

Abstract

This case study presents the challenges faced and learning curve built while achieving longer departures with light / slim casing design instead of conventional / heavier design in shallow coastal water field in UAE. This paper intends to explain the challenges that were encountered and the process of mapping the lessons learnt to ensure improvements along the process. The process involved the casing points analysis evaluating the competent formations options, continues optimization of well trajectory by increasing the inclination across problematic formations while drilling the intermediate section (limited in previous drilling campaign in the area), the evaluation of the impact caused in the consecutive 8 ½" phase (longer section), implementation of best practices to mitigate stability issues and Invisible Lost Time (ILT) methodology application to minimize hole exposure duration. The challenging campaign had the objective of saving cost by reducing one [FQ1] construction [FQ2] phase and continues achieving longer departures successfully which was a milestone during the well construction, thus a learning curve was built focused on continuous improvement of key operations. After completing more than 100 wells, the most beneficial point this change has offered is drilling long departure wells saving one phase in comparison with the conventional design in the area, which is the key element for cost reduction and also allowed to reduce crew exposure to heavier casing handling improving HSE risks. Currently, a maximum departure/vertical section of 10,700 feet has been achieved with light/slim casing design. Overall duration saving is 16 days compared with the best heavy casing design duration and 20 days with average heavy casing design duration with 35% saving duration. Drilling light casing design instead of conventional heavy casing design enable average of USD 2 million saving per well. The consolidated experience built throughout planning and execution since the first well, enabled an important performance improvement based on the learning curve built along the years. Nowadays, many fields require drilling wells with long vertical section / departures to reach further targets, away from the feasible surface locations. Additionally, cost reduction is another concern due to Oil Market fluctuation by applying new strategies and optimizing the performance without jeopardizing but improving the HSE at the same time. This paper presents a novel approach to well construction by showing the lesson learn that allowed well duration reduction, drilling more wells per year and consequently bringing early production, increasing efficiency and significantly reducing cost, therefore increasing productivity and profitability, at the time of contributing to HSE improvement.