Application of Couette Flow of Non-Newtonian Power-Law Fluids in Dynamic Surge/Swab Pressure Prediction


  • Mohammed Abdul Ameer Al-humairi, Faleh H. M. Almahdawi


The displacement of drilling fluid by the movement of the drill string or casing pipes, produces pressure variations in the borehole. The velocity of this displacement governs the magnitude of the pressure change which can be add or subtract to the hydrostatic pressure of the drilling mud to produce surge or swab pressure respectively. It is generally accepted that the pulling and running of pipe in a liquid – filled borehole, cause pressure surge or swab.

The prediction of pressure surge or swab is of economic importance in wells where the pressure must be maintained within narrow limits to prevent lost circulation and formation – fluid influx. For these wells, the drilling engineering needs for the best possible method of calculation surge and swab pressures to drill wells with a minimum of trouble and problems.

It is similar to a moving cylinder, concentrically placed in a liquid-filled outer cylinder. This flow phenomenon has a wide variety of applications in the solution of problems in petroleum, chemical, mechanical, and ceramic industries.

Key word: Non- Newtonian, surge pressure, swab pressure