Experiments of Blast Furnace Slag as a Mud Cake Modifier and Its Trial in Horizontal Well I306H

Abstract

Blast furnace slag (BFS) was added into drilling fluid as a mud cake modifier (MCM) for the reuse of BFS. The effects of MCM on drilling fluid rheology and shear strength of cement- formation interface (SSCFI) were evaluated. The experimental results showed that the optimized formula of the drilling fluid has 1.0 wt% MCM. The simulation re- sults showed that SSCFI increased significantly with the addition of MCM. Based on the mechanism analysis of BFS as an MCM to improve SSCFI, it is found that the transformation of mud cake to agglomerated cake (MTA) can be the main reason. The trial result of horizontal well I306H in Laojunmiao oilfield in China showed that the one-time success rate of cementing operation was 100% and the high quality rate was 79.78%. This horizontal well is flowing well after perfora- tion with oil production of 11.5t/d and the water cut is only 9%. Compared to the adjacent horizontal wells after fractur- ing, the oil production rate is increased by 228.57%-259.38%. Obviously, the effect of BFS as an MCM is self-evident. Meanwhile, this research provides a new way for the recycling of BFS. established (17) and the synergism of MCM with the form- ing agent of agglomerated cake (18) was studied (19). The application effects of six oilfields in China showed that the MTA method improves significantly the qualified rate and high quality rate of well cementing (20, 21). But, this method is not used in horizontal well. Based on the drilling fluid and cement slurry from Laojunmiao oilfield in China, the effects of BFS as an MCM on the drilling fluid rheology were investigated. The relationship of SSCFI with the addi- tion of MCM and curing time was evaluated. The mecha- nism of BFS as an MCM to improve SSCFI was analyzed. The trial effect of horizontal well I306H was introduced in Laojunmiao oilfield in China. 2. MATERIALS BFS is from Shengda Material Co., Ltd., Wuhan, China.