Modeling fluctuating pressure in the eccentric annulus with a four-parameter rheological method. (July 2022)

• Record Type: Journal Article
• Authors: Liu, Zhikun; Liu, Chenglu; Zhang, Wei; Wang, Yong; Cao, Jie
• Is Part Of: Energy reports. Volume 8(2022)Supplement 4
• Page Start: 1405
• Page End: 1417
• Publication Date: 2022-07
• Subjects: Four-parameter rheological model -- Eccentric annulus -- Fluctuation pressure -- Parameter analysis; Power resources -- Periodicals; Energy industries -- Periodicals; Power resources; Periodicals; Electronic journals; 621.04205
• DOI: 10.1016/j.egyr.2022.01.230
• Languages: English
• ISSNs: 2352-4847

Abstract

Abstract: The existing calculation models of fluctuating pressure are mainly based on Bingham fluid, power-law fluid and Heba fluid. These rheological models have certain limitations in the scope of application, and it is difficult to accurately describe the actual rheological curves of most drilling fluids. Based on evaluating the calculation model of power-law fluid pressure in eccentric annulus, the constitutive equation of the four-parameter rheological model is extended, and the calculation formula of annular pressure loss is established. In this research, we consider the calculation formula of annular flow under different boundary conditions. The model of fluctuating pressure in the eccentric annulus is obtained using cubic spline interpolation and Gauss integral equation. Compared with the experimental data from concentric annulus and eccentric annulus, the calculated results are in good agreement with the experimental results, compared with the laboratory test data, the error is within the range of ± 10%, indicating that the model is sufficiently accurate to meet the requirements of field operations. In addition, the sensitivities of trip rate, drilling fluid flow index and drill string to wellbore size ratio are analyzed. Under the condition of totally eccentric annulus, the gradient of surge pressure decreases to around 50% of that for concentric annulus. The tripping velocity should be strictly limited for operations in the narrow annular space.