Cementing Quality Of Small Wellbore In Dagang Oilfield

In order to improve the cementing quality for the close clearance wells in Dagang Oil Field,the method for exactly calculating the flow resistance of the close clearance well cementing,the technologic measure for improving the displacement efficiency and as well as the integrated technology for oil-gas-water inhibiting are studied for practical use in this paper.And meantime this paper has developed the close clearance well design method and technique suitable for Dagang Oil Field.The application experiment in many close clearance wells onsite has proved that:the method and technique which was developed in this paper had improved the cementing quality evidently,and had a excellent experimental value for the close clearance well in Dagang Oil Field.This paper emphasized on the following aspects of the work:(1)Analyzed and studied the influence of the temperature and annular clearance to the cementing flow calculation,and explained that:the low temperature estimate deviation and low annular clearance were the fundamental reasons for the great deviation when adopting the general method for the close clearance well cementing designing.(2)Set up the flow shear stress model concerning the temperature coefficient.By using this model,the rheology property of the cement slurry or drilling fluid under different temperatures could be forecasted.(3)Developed the flow profile differentiate standard when the Power-law fluid flowing in the close clearance annular,and inducted the hydraulic diameter,set up the modified Renault Number calculation method for the close clearance eccentric annular and the modified calculation method for the flow friction coefficient.(4)Put forward the method to confirm the close clearance interval friction coefficient by statistics.(5)The close clearance annular casing centralization should be higher than 80%,adopting the pad fluid turbulence and increasing the degree of the pad fluid turbulence were the effective measures to improve the displacement efficiency.(6)Put forward the detailed method for designing the anti-fluid-channeling cement slurry according to the magnitude of the stratum gas tongue potency.(7)Carried out the application experiment of the integrated technology exhibited in this paper for the cement operation in many close clearance wells in Dagang Oil Field.