Abstract
The application of the hole cleaning device in downhole is a new technology that can improve the problem of cuttings accumulation in the annulus and improve the hole cleaning effect of the wellbore during drilling. In this paper, the Reynolds Averaged Navier–Stokes model, together with the Realizable k-ε turbulence model, are used to perform transient simulations. The effects of rotational speed, blade shape, and helical angle on the initial swirl intensity and its decay behavior along the flow direction are studied. The swirl number, the initial swirl intensity, the decay rate, the tangential velocity distribution, and the variation of pressure are analyzed. The results indicate that the swirl number of the swirl flow exponentially decays along the flow direction. The straight blade and V-shaped blade have different swirl flow induction mechanisms. Under specific drilling parameters, the critical helical angle is determined for both types of blades. When the selection of the helical angle is close to the critical value, the swirl flow will be close to the axial flow, which is of little help in hole cleaning. Moreover, the rotation direction of swirl flow will change when the helical angle exceeds the critical value.
Highlights
In recent years, the large-scale development has been made in complex hydrocarbon reservoirs, i.e., low permeability, unconventional, deep water, etc
It is reported that nearly 70% of accidents causing drilling downtime are related to the stuck pipe, while almost one-third of the total drilling accidents are caused by inadequate hole cleaning [3,4]
This is because the increase of blade height can improve the ability to induce swirl flow, but the design of the blade height is not allowed to be too large in a complex downhole environment, so the blade height is not taken into account
Summary
The large-scale development has been made in complex hydrocarbon reservoirs, i.e., low permeability, unconventional, deep water, etc. The horizontal well drilling technology has been increasingly widely used to enhance the recovery efficiency of complex reservoirs, and it can significantly increase oil and gas production and ease the energy shortage problem [1]. Insufficient hole cleaning will lead to safety problems, such as stuck pipe, premature wear of drill bit, high torque, and high drag, especially in the deviated and horizontal wellbores [2]. It is reported that nearly 70% of accidents causing drilling downtime are related to the stuck pipe, while almost one-third of the total drilling accidents are caused by inadequate hole cleaning [3,4]. For drilling engineering, the effective removal of cuttings particles is of great significance in ensuring drilling safety and improving drilling efficiency
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