Application of MEG Drilling Fluid in Slim Hole Sidetracking Wells

The commingled crude drilling fluid was deployed for slim hole sidetracking and it was not environmentally benign. The reaction mechanism of MEG monomer 'was discussed. The formulation was optimized by taking the lubrication and inhibition of MEG drilling fluid as key evaluation criteria and the optimum formulation was then tested. Four sidetracking wells'practices indicated that no logy or sticking occurred and 7. 2 day rig days saved. The lubricating coefficient reduced by 34. 6% comparing with that of e-mulsified crude oil(15 % - 20 %) drilling fluid. MEG drilling fluid had better formation damage control. WEN 5-41C had a 14. 4 t BOPD and this was greater than that of WEN 5 BLOCK by 128. 4%. SHEN-128C well is a unique gusher well in the SHEN 229 BLOCK presently. It was proved from the data that MEG drilling fluid present excellent lubrication and inhibition and better formation damage control capacity. It is an attractive alternative when drilled in challenge wells including serious water sensitive formation, high angle deviated holes and horizontal wells.