Research and application of positive-pressure film-forming drilling fluid technology
Water-based film-forming drilling fluid technology is a kind of wellbore strengthening technology which has been studied and developed rapidly in recent years.It was found in the experiment that the positive pressure membrane-forming additive PMF can effectively improve the pressure-bearing capacity of the formation.A positive-pressure film-forming drilling fluid system was formed by combining organic salt drilling fluid or potassium salt polymer drilling fluid with PMF.Permeability recovery of the drilling fluid system is high and can effectively protect the reservoir.Under conditions of 60～160℃,the pressure-bearing capacity of the formation plugged by the positive-pressure film-forming drilling fluid system could be 5.6 MPa.When plugging a 0.5 mm wide formation at 150℃the pressure-bearing capacity of the formation could reach 12 MPa.When plugging a 1.0 mm wide formation,the pressure-bearing capacity of the formation could reach 6.8 MPa.The sand bed plugging test showed that the bearing capacity of the sand bed could reach 30 MPa.When plugging the core,pressure pressure-bearing capacity of the core could reach 15 MPa.Downhole pressure tests were conducted on two offshore wells using the positive pressure membrane-forming additive PMF,showing good results.
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