Oil-based and synthetic-based drilling fluids are important to the industry because they provide excellent performance under the most difficult drilling conditions. They are the fluid of choice for deepwater, high angle, and extended reach drilling, as well as most high temperature environments. To maintain the integrity of these systems, engineers depend upon data generated by a standard set of field test procedures contained within API RP 13B-2 (ISO/FDIS 10414-2).
In 1997, an API Work Group, composed of a cross-functional team of operators and suppliers, began work to improve the existing oil mud chemical analysis field procedures. After more than 5 years of effort that included 13 multi-laboratory round robins, many significant gains were made. These included advances in our understanding of the factors that affect oil mud alkalinity, and the elimination of interference in several of the color-change endpoints. In the past, these issues had been causing errors in the determination of excess lime, water phase salinity, and calcium, all of which affect critical oil mud functions such as wellbore stability, emulsion stability, rheology control, and filtration behavior. The work enhanced oil mud field test data by improving reproducibility and reducing standard deviation from highs of 50% to less than 10%. As the result, the industry will be able to make better mud-related engineering and operational decisions when oil-based drilling fluid is used, which can lead to less chemical usage, lower mud costs, and lower drilling costs.
It is a specific goal of this paper to heighten the industry’s awareness of improvements to oil mud field test standards in order to facilitate their distribution and use. It will describe the learnings and improvements made to the existing oil mud chemical analysis field procedures. To help transfer these to the rig site, a copy of the revised section 7, Oil Mud Chemical Analysis, from API RP13B-2 (Recommended Practice Standard Procedure for Field Testing Oil-based Drilling Fluids) is presented.