Technical Principle of Integrated Solidification and Cementation at Cement-Formation Interface with Mud Cake to Agglomerated Cake (MTA) Method and Its Oilfield Application

摘要

The technical principle of integrated solidification and cementation at cement-formation interface (ISCCFI) with Mud Cake to Agglomerated Cake (MTA) method based on the mud cake modifier and forming agent of agglomerated cake can be divided into two steps. Firstly, add the mud cake modifier (the amount is 1 % to 3 %) to the drilling fluid before drilling the isolation section, and keep this proportion until the well completion. Secondly, prepare 3 to 4 cubic meters of prepad fluid based on forming agent of agglomerated cake before the well cementing operation. This new method doesn't need to change oilwell cement slurry system. In order to verify the practical cementing effect of MTA method, it was applicated in 16 adjustment wells (9 conventional wells and 7 heavy oil wells) in the old area of two oilfields in China. The interpretation results of CBL/VDL (Cement Bond Logging/Acoustic Variable Density logging) show that the qualified rate of casing-cement interface and cement-formation interface is up to 100 %, and the qualified rate of cement-formation interface increased by 30 % in Shengli oilfield and the average high-quality rate of all the isolation section length at cement-formation interface reaches 90.48 % in Henan oilfield.