XHC - Hole Clean Solution
THE PROBLEM
Effective hole cleaning to enable the smooth running of a rig is a constant challenge. In high inclination wells it requires activation of a viscous coupling between the mud and the rotating drill string. In marginal wells, where power is limited, the correct combination of variables such as drill string rotary speed, fluid viscosity, drill pipe diameter etc. is often unavailable for effective hole cleaning, wiper tripping in ERD wells is discouraged since hydraulic and mechanical risks increase exponentially with step-out. Extended reach open hole sections are typically open for longer periods of time and so are subject to hole degradation.
AN ALTERNATIVE VIEW
Utilizing the Xtreme-Clean XHC to improve hole cleaning enables the hole to be cleaned with a lower rpm, improving cuttings removal, with the added benefit of reducing ECDs. The hole may be kept clean with a programmed wiper trip over the spacing of the tools only. Typical applications may use as few as 10-15 tools for effective hole cleaning, particularly applicable to wells where the rig power is limited.
OUR SOLUTION
The XHC is a drill string tool intended to improve hole cleaning in ERD type well profiles with sail/tangent angle exceeding 30º. It is an integral drill string component consisting of a short mandrel with no moving parts, shaped to stimulate cuttings recirculation; agitating the cuttings from the low side of the wellbore, and moving them to the upper side of the hole which is where the higher velocity drilling fluid is located. This enables the cuttings to be incrementally moved up the wellbore.
The XHC is particularly appropriate for use in the “avalanche zone” high angled sections (30° – 65° inclination) where cuttings build up can lead to instability, and subsequent pack off. The tool is suitable for both inside the casing or open hole environments.
We have proprietary simulations to predict when cutting are likely to fall out of the mud during transport up the hole, we then plan to have tools spaced slightly less than the cuttings dropout period, efficiently and effectively removing the cuttings from the wellbore. For example, if the cuttings removal increment was determined to be around 200ft then positioning a XHC sub at every 3 stands will result in optimal cuttings removal. Inclusion of the XHC in the drill string means that changes in rheology, cuttings size, or mud properties can be accommodated without increasing the risk of cuttings bed build up.