Effect of Formation Cutting's Mechanical Properties on Drilling Fluid Properties During Drilling Operations

In drilling operations, the fine drilled cutting are mixed with the drilling fluid. As a result, the properties of the drilling fluid, such as density and rheological properties, will change based on the cutting properties. Previous studies investigated the effect of rock type with different loadings on the drilling fluid properties. However, the effect of cutting's mechanical properties variation was not addressed. In this paper, the effect of variation in cutting's mechanical properties on the drilling fluid properties was investigated in sandstone reservoir. Particles of sandstone formation core samples with different compressive strength (UCS) and different Young's modulus (E) were mixed, in different percentages, with the drilling fluid. The mechanical properties of the cuttings were determined in the laboratory using destructive method. The drilling fluid density and rheological properties were measured using mud balance and 900-Viscometer(R), respectively. The results of this work showed that, for sand content less than 10 wt%, the mechanical properties of the drilled cutting have no effect on drilling fluid properties. The effect of the mechanical properties of the drilled cutting becomes more significant for sand content greater than 10 wt%. In this range of sand content (> 10 wt%), for a constant UCS, drilled cutting with a smaller Young's modulus have a higher effect on the drilling fluid rheological properties compared to drilled cutting with a larger Young's modulus. On the other hand, for a constant E, drilled cutting with larger UCS showed a higher effect on the drilling fluid rheological properties compared to drilled cutting with smaller UCS values.