The volume and type of solids in a drilling mud system can adversely affect mud properties, reduce penetration rates, cause damage to drilling equipment, and increase total drilling costs. Efficiency controlling the solids content of the mud system is an important phase of an efficient and cost-effective drilling program. The three basic methods of removing solids are dilution and/or displacement of whole mud, settling and mechanical solids-control equipment.
A field application of the economic and performance analysis model for a closed-loop system implementation. A district had realized substantial benefits through more effective solids control in earlier years and was interested in 1986 in analyzing the economics of further improvements in solids control. The economic and performance analysis programs were run to predict the costs, potential savings, and recommend a suitable solids control system. It was a nine-well (2-vertical and 7-directional, 4300 ft average depth) infill drilling program within the city limits, which imposed certain constraints such as minimal or no reserve pits with all the extra mud and wastes hauled for off-location disposal.
During a drilling operation, drilled solids or cuttings generated at the bit mix and interact with the initially formulated drilling fluid and bring about changes in its density, rheology, and other properties. These changes are affected by such factors as the flow-rate, density, size distribution and the degradation tendency of the drilled solids These factors, in turn, are determined by such interacting variables as lithology, fluid properties, penetration rate, and the wellbore geometry.