on zddp by itself as well as lubricant blended with zddp 9 1 table 6 shows a reduction in the cof of the drilling fluid with the addition of zddp formate based drilling fluids represent another class of inhibitive water based drilling fluids a formate based drilling fluid was formulated with 5 potassium formate v v polymers water and simulated drill solids lubricity testing was done on zddp the results show that the addition of zddp lowers the cof of the formate based drilling fluid oil based drilling fluids have naturally low cof but deeper and extended drilling is creating the need for further reductions in torque and drag an oil based drilling fluid was formulated according to the drilling fluids zddp was tested as a standalone lubricant table 8 shows that zddp lowered the cof of the drilling fluid a completion fluid is a solids free liquid placed that is sometimes used at the final stages of well completion completion fluids are typically brines chlorides bromides and formates the fluid is meant to be chemically compatible with the reservoir formation and fluids and is typically filtered to a high degree to avoid introducing solids to the near wellbore area zddp was tested in a saturated solution of potassium formate 75 active and potassium formate diluted 1 1 with water table 9 shows that the cof of the completion fluid was reduced with the addition of zddp shale accretion was measured by observing the adhesion of clay onto a metal pipe oxford shale was sized through 6 8 mesh screen oxford shale is noted for its u201c stickiness u201d and is a.