Field Verification of the Effect of Differential Pressure on Drilling Rate

Abstract

A field study was conducted on eight South Louisiana wells to determine the effect of differential pressure on the instantaneous rate of penetration in shale.Drilling rate is affected significantly by changes in differential pressure and may be reduced as much as 70 percent as the differential fluid pressure is increased from 0 to 1,000 psi. When the formation pressure becomes greater than the mud-column pressure, drilling rates continue to increase, sometimes at an increasing rate. The sensitivity of drilling rate to differential pressure depends upon the magnitude of the bit load. Overburden pressure and the hydrostatic head of the mud column over the intervals studied had no detectable erect on penetration rate.Increases in formation pressure can be detected by an increase in penetration rate. The careful observation of drilling rate can help avoid kicks and allow the well to be maintained at minimum overbalance hydrostatic conditions. Decreased well-drilling costs and an increased drilling rate will result.