An experimental investigation of drilling mud discharged into a flowing stratified environment

Graduation date: 1984An experimental study of the short-term fate of a drilling mud discharged into a flowing stratified environment was conducted to determine its dilution and settling characteristics. The drilling mud used in this test had a specific gravity of 1.184 and a composition of 12 percent by weight high-gravity solids (BaSO₄) , 15.2 percent low-gravity solids and 72.8 percent water. Samples were taken within the water column and on the bottom at different depths, Y/D, at various distances from the source, X/D. They wer analyzed for total solid (TS) and BaSO₄ concentration. Samples were also collected at the exit of the discharge pipe and analyzed for TS concentration in order to study downpipe premixing. TS concentration within the water column decreased from 271.8 mg/gr of solution at the source to 2.78 mg/gr of solution at X/D value of 25 and to 0.25 mg/gr of solution at X/D value of 410. TS concentration at the exit of the discharge pipe showed only slight in-pipe mixing for the test Froude Number of 0.69. The ratio of barium sulfate to TS from samples collected on the bottom dropped continuously from 63 percent at X/D = 113.2 to 23 percent at X/D = 170.9. A comparison of TS concentration at the centerline of the plume calculated by the Offshore Operators Committee computer model (00C) with the experimental results showed a good agreement for X/D values from 40 to 410