Drilling Fluid Technology for a Long Horizontal Section in a Turbidite Reservoir of the Bonan Depression, Shengli Oilfield

To address problems such as hole instability, high sliding friction and poor cuttings transport encountered in drilling horizontal well in a turbidite reservoir of the Bonan Depression, Shengli Oilfield, the inhibition of organic amine drilling fluids was evaluated by linear expansion test in laboratory, the plugging effect of both"crude oil and extreme-pressure lubricant" was evaluated by a HTHP filtration experiment.Then the effect of the oil content on drilling fluids performance was also evaluated, by which an organic amine sulphonated polymer drilling fluid containing a high content of crude oil was developed.Lab test results demonstrated that organic amine sulphonated polymer drilling fluids with high contents of crude oil possess satisfactory temperature tolerance, rheology, inhibitive behavior, lubricity and stable performance, which can meet field requirements.This drilling fluid system has been applied in 9 wells in Bonan Block, with no hole collapse or pipe sticking.Typically in Well Yi 123-9HF, the average hole enlargement rate at the third spud section was 5.8%, the friction at the horizontal section remained at 60-80 kN, which demonstrates the good hole collapse prevention ability and the lubricity of the drilling fluids.Therefore, organic amine sulphonated polymer drilling fluids with high contents of crude oil can effectively resolve problems in drilling horizontal wells in a turbidite reservoir of the Bonan Depression, Shengli Oilfield, and provide new technical support for raising penetration rate in drilling similar reservoirs.