Slim-Well Completions: A 3D Numerical Approach for Displacement to Design Effective Cementing Fluids

Abstract

Slim-well construction helps to significantly reduce overall well construction costs. The first step of the successful completion process is achieving effective zonal isolation. Slimhole configurations experience higher shear rates at standard annular pump rates as compared to conventional configurations. The increase in shear rate could exacerbate intermixing of the fluids, diffusion, and fingering in the annulus, thereby leading to incomplete mud and filter-cake removal and poor cement placement. Real-world consequences of these phenomena can include interzonal communication, loss of production, remedial squeeze work, and even well abandonment. Whether a conventional or slim hole well, designing an effective zonal isolation job involves balancing two technical challenges: (1) providing adequate hole cleaning through effective erodibility shear stresses; and (2) reducing channeling of mud or spacer by minimizing intermixing at fluid interfaces, controlling diffusion and minimizing fingering in the annulus. This paper deals with the underlying interactions between fluids and the challenge of controlling the aspects affecting intermixing Intermixing lengths can commonly be as high as 500 feet for slimhole cementing jobs owing to the large difference between central and peripheral velocities of the annular fluids. In an attempt to minimize this problem, a three-dimensional (3D) numerical fluid-flow simulator was used to compare flow profiles in a low clearance 143/4-in. × 133/8-in. annulus to those in a conventional 16-in. × 133/8-in. annulus. Rheologies of the annular fluids were accurately modeled using the Herschel-Bulkley scheme. Using the same fluids and pump rates, numerical simulations in the slimhole configuration clearly showed worse displacement as compared to the standard configuration. The effects of the three rheological parameters viz., τ0, µ∞, and n of the fluids, pump rate and eccentricity on dynamic velocity profiles, displacement efficiency, intermixing lengths, and top of fluids were then studied to improve drilling-mud removal, and cement slurry placement. Results of various simulations are shared to reveal the properties and parameters that are needed to help achieve a competent cement sheath over the desired interval.

Application of soft computing approaches for modeling annular pressure loss of slim-hole wells in one of Iranian central oil fields

“…Reduction of the overall drilling costs has been mentioned among the most significant issues in the petroleum industry (Brunsman et al, 1994;De Sousa et al, 1999). One of the most reliable methods to attain a considerable decrease in costs is the use of slim-hole drilling (Jafarifar et al, 2020;Pks and Yerubandi, 2010;Scott and Earl, 1961;Cohen et al, 1995).…”

The Effects of Density Difference on Displacement Interface in Eccentric Annulus During Horizontal Well Cementing

“…There is no doubt that a bad annular cementing quality can lead to any of the following problems or disasters: blowout, leakage at surface, destruction of subsurface ecology, potential contamination of freshwater, delayed or failed abandonment, as well as loss of revenue. Many factors can affect the displacement interface shape [1][2][3][4][5][6][7][8][9], such as:…”

A Combined Mixer Design with Helical Blades to Probe Rheology of Complex Oilfield Slurries and Pastes

“…The industry now has access to state-of-the-art CFD-based simulators to predict displacement in a fully 3D wellbore environment (Savery et al 2007;Pks and Yerubandi 2010). Various families of drilling muds, ranging from oil-based, synthetic-based, or water-based, can be used to drill the boreholes to the desired depth and set the casing.…”