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API Bull 75L-2007 (R2013): Technical Guide to Drilling Fluid Processing System Evaluation
Understanding the Scope, Technical Requirements, and Compliance Recommendations for API Bulletin Drilling Fluid Processing Systems
Scope and Application
API Bull 75L-2007 (2013), officially titled “Drilling Fluid Processing Systems Evaluation,” provides standardized methodologies for assessing the performance of equipment used in drilling fluid processing. The bulletin covers both primary and secondary treatment devices commonly deployed in solid control systems, including but not limited to shale shakers, desanders, desilters, mud cleaners, centrifuges, degassers, and agitators.
The scope explicitly excludes equipment used solely for fluid mixing and transfer unless such equipment contributes directly to solids removal or fluid conditioning. The bulletin is applicable to both water-based and non‑water‑based drilling fluids and addresses evaluations under controlled test‑loop conditions as well as offshore installations.
API Bull 75L serves as a supplementary document to other API recommended practices such as API RP 13B (Rheology and Filtration Control) and API RP 13C (Shale Shaker Screens). It is intended for use by drilling engineers, mud engineers, equipment manufacturers, and regulatory personnel involved in ensuring optimal processing system performance.
Technical Requirements for Equipment Evaluation
The bulletin defines specific test conditions and acceptance criteria for each piece of equipment. A summary of the primary evaluation parameters is provided in Table 1.
| Equipment | Performance Parameter | Unit | Typical Acceptance Limit |
|---|---|---|---|
| Shale Shaker | Effective screen area utilization | % | ≥ 85 % at design flow |
| Shale Shaker | Solids removal efficiency | % | ≥ 90 % for 75 µm |
| Hydrocyclone | D50 cut point | µm | 10 – 15 µm at 30 psi |
| Hydrocyclone | Water recovery | % | ≥ 95 % by volume |
| Decanter Centrifuge | Solids moisture content | % | ≤ 30 % wet weight |
| Decanter Centrifuge | Solids recovery | % | ≥ 85 % for >5 µm |
| Degasser | Gas removal capacity | scf/bbl | ≥ 95 % at 100 scf/bbl |
These performance limits are intended as guidelines; actual site-specific conditions may require adjustments. The bulletin stresses that test conditions must be reported in detail, including fluid density, viscosity, solids content, and flow rate.