Amr Heikal write to ” Blue Economy ” HPWBM in Kuwait for drilling challenging intervals.
Wells drilled previously using Oil Base Mud
The Situation
Well-bore instability / Caving in Ahmadi and Wara shale.
Mitigate differential sticking tendency across depleted Mauddud.
Minimize induced losses due to low pressure across Tuba and Mauddud limestone.
NPT due to possible well-bore instability & stuck pipe.
The Solution
Kuwait Drilling Fluids recommended the High-Performance water-base drilling fluid system as opposed to a non-aqueous mud. By employing the aqueous system, the operator was expected to stay within the programmed cost, while effectively drilling to casing point. The system has been shown to provide excellent shale inhibition and borehole stability. The first application was successfully completed on 12.25-in and 8.1/2-in sections were drilled & cased successfully as per plan with stable wellbore indicated by the smooth trips and no string stalling or sticking tendency. The customized fluid proved its success.
Inhibition and performance for conventional KCl Polymer Mud with Sulphonated Asphalt Mud was enhanced by using specialized chemicals below.
Polyamine derivative suppresses clay hydration & swelling by using ion exchange mechanism.
Sealing polymer improve well-bore stability by sealing pore throats and micro fractures.
Customized Bridging – Sealing of pore throats by using CaCO3 and Resilient Graphite based on pore size distribution to reduce fluid invasion. Effective bridging is achieved to sustain high overbalance by using customized bridging along with Sealing Polymer to avoid differential sticking tendency.
The Results
The performance of the system was excellent with no reports of hole pack-off.
- Cuttings were dry & firm inside when broken indicating good inhibition.
- No bit balling observed.
- Observed normal torque and drag.
BRIDGING TECHNOLOGY
Proper particle size distribution bridging maintain Graphite ( 4 lb/bbl) in addition to Calcium Carbonate different size blend improved the hole stability and eliminated the tendency of down hole losses and sticking tendency by bridging formation pore throats effectively, reduce fluid invasion hence avoid differential stuck pipe tendency. This was evidence by Permeability Plugging Test (PPT) performed under conditions resembling the actual formations e
CONCLUSION
The HPWBM has been field trialed in Kuwait as an environmental and performance driven alternative to OBM and the results achieved have been comparative to OBM.
Application of the HPWBM has mitigated the environmental impact and cost associated with disposal of OBM cuttings.
Selection of proper mud weight on the basis of geo-mechanical study is the key to avoid any problem.
Latex compound was effective along with customized bridging by using CaCO3 and Resilient Graphite to reduce fluid invasion hence avoid differential sticking tendency.
: Amr Heikal – Business Development and Technical Manager – Kuwait Drilling Fluids.
