Improved Drilling Performance in Lake Maracaibo Using a Low-Salinity, High-Performance Water-Based Drilling Fluid

Abstract

Abstract Improved drilling techniques have overcome many of the inherent difficulties associated with the delivery of Icotea and Misoa wells in the West Urdaneta Field of Lake Maracaibo. Advancements such as rotary steerable assemblies, logging-while- drilling (LWD) tools, annular pressure subs and new bit designs have allowed drilling of extended reach and horizontal wells to become routine. However, borehole instability and lost circulation problems have continued to negatively impact operations, compounding well delivery costs. In an effort to address these problems, a variety of non-aqueous fluids (NAF) and water-based muds (WBM) have been used. While each provides distinct advantages, there has never been a system which could solve all problems associated with drilling the Icotea and Misoa formations. Lost circulation and wellbore instability (defined by almost continual caving of shales in the La Rosa formation) have plagued NAF applications in this field. A variety of WBM systems have been used and each one has also presented its own problems including hole enlargement, bit balling, accretion, low rates of penetration, insufficient hole cleaning, and the need for excessive backreaming. Finding a fluid that would deliver step-change performance in of drilling efficiency compared to previously used systems, while also adhering to the strict environmental limitations for the area, was paramount to continue economically viable drilling operations in the Urdaneta Field. This challenge was met using an environmentally benign, low-salinity high-performance water-based mud (HPWBM), which was field tested in the intermediate section of the Icotea and Misoa wells. The novel fluid was used to drill through the problematic Laguna, Lagunillas, and La Rosa formations. By analyzing the field tests results, conducting after action reviews (AAR) and maintaining a productive dialogue between all parties involved, the operational performance of these wells showed substantial and continual improvement. The low-salinity HPWBM is now our system of choice for drilling intermediate hole sections in the West Urdaneta Field. This paper provides a detailed technical overview of the new HPWBM, provides and the results of the early field tests and of subsequent wells, demonstrates enabling impact of this new technology on driving continual operational improvement.