| Popis: |
The requirements for offshore drilling continue to evolve to meet the needs of the industry, new technologies and drilling practices need to be adopted to accommodate these increasingly challenging environments. These new environments present challenges that include, but are not limited to, hole cleaning, wellbore stability, narrow margin drilling, and drilling fluid system stability over a wide range of temperatures. A high degree of planning and preparation is required in order to execute these wells, which will reduce any chance for a nonproductive time and deliver expected return on investment of the project. The need for a drilling fluid system that is designed to drill these challenging wells, is crucial to ensure the success of a project. The well presented in this paper was the first well drilled in Lebanon and emphasizes the benefits of a low equivalent circulating density (ECD) impact drilling fluid when utilized in a deep-water environment. During the drilling phase of the project, the fluid was able to meet the demands of the operation by providing a low ECD while dealing with a range of temperature gradients that are associated with deep-water environments. The drilling fluid's unique performance ensured that any relevant nonproductive time events were mitigated and ensured the final delivery of the well. In addition, the fluid was able to meet these challenges with no additional treatment or modifications to the original planned fluid parameters for the project. The low-impact, non-aqueous drilling fluid (LDIF) provided shear-thinning properties, flat rheological profile and non-progressive rapid-set/easy break gels. The fluid system benefited from a unique design that allowed the use of high yielding organophilic clay while utilizing an industry established low viscosity base oil. The synergy of the drilling fluid system when tailored to the base oil with kinematic viscosity as low as 1.7 cSt was able to provide rheological properties commonly associated to a clay-free non-aqueous base drilling fluid. The drilling fluid was able to provide a rheology that delivered a flat profile over the operating temperature range, while facilitating control of the ECD through the well. This operational experience shows how the choice of a proper fluid system together with a proper base fluid can ensure the unique challenges for the industry today can be successfully met. |
