Most oil and gas companies prefer to use non-aqueous fluid (NAF) or Oil Base Mud (OBM) compared to water based mud systems (WBM) to drill challenging wells. The NAF system has generally been considered technically superior to conventional water based muds in the areas of well-bore stability, inhibition, lubricity and differential sticking tendency. However, as the industry strives to achieve improved environmental solutions, the introduction of high-performance water based mud (HPWBM) creates the possibility of same performance where OBM is typically used. A sustainability-driven innovation by Kuwait Oil Company (KOC) and Baker Hughes could challenge industry norms.
KOC historically used diesel-based non-aqueous fluid (NAF) to drill more challenging shale formations, mainly due to lubricity and wellbore stability requirements. But with the government’s initiative to improve environmental standards, Kuwait Oil Company (KOC) and Baker Hughes identified that a high-performance water based mud (HPWBM) could be a suitable and environmentally acceptable alternative to diesel-based fluid.
“In the interest of Kuwait Oil Company’s goal to keep pace with the global obligation to preserve the environment in the oil sector, for the first time in the State of Kuwait, KOC with a success rate exceeding 88% implemented a new technology to replace the diesel-based system with a high performance water base drilling fluid system,” says Ali Al-Saleh, KOC’s Manager of the Technical Support Group. “The results achieved all operational expectations and reduced the negative emissions on Kuwait environment.”
KOC Development Drilling Group II and Baker Hughes task force set out to test this new solution in 2016 with resounding success in HPWBM. The design took into consideration chemical inhibition to reactive shale formations, density profile prediction, bridging technology to retain wellbore strength, downhole fluids modeling and rheological parameters, highly lubricious to minimize torque and drag, hole cleaning, and minimizing reservoir damage.
In addition, in 2019, Kuwait Oil Company (KOC) and Baker Hughes working group developed for the first time in Kuwait a customized HPWBM based on extensive laboratory analysis to achieve OBM performance and fill in the gaps between OBM and HPWBM at an effective cost.
Tests included X-RAY diffraction, cation exchange capacity tests, linear swelling tests and shale dispersion tests. The system can be used with water ranging from freshwater to saturated monovalent brines, including those containing sodium chloride, and potassium chloride.
The team comprised Ali Al-Saleh, KOC Manager of the Technical Support Group; Hadi Saad Al-Jami, KOC Manager of Development Drilling Group II; Meshal Al-Khaldy, KOC TL-Development Drilling & Workover Team VI; Abhijit Dutta, KOC Specialist; Abdelrahman Hamed, KOC Drilling Fluids Specialist Team VI. From Baker Hughes, Prakash Jadhav, Service Delivery Manager; Ketan Gadhiya – Service Delivery Coordinator; and Amr Heikal – Service Delivery Coordinator.
The team expected that the HPWBM would be able to complete well targets, achieve KPIs, and mitigate the typical environment impact of using an OBM. In comparing the actual results to those achieved with traditional solutions, the HPWBM, with no diesel or environmental discharge hazard, achieved a slightly higher average rate of penetration. HPWBM has many other advantages, like the use of brine (or other aqueous based brine), as a completion fluid would not be a problem. HPWBM has higher integrity filter cake and cakes easier to dissolve using enzyme breakers while excess emulsifiers in OBM could cause reservoir damage.
Logistics plays very important role in the selection process as HPWBM do not need any transport and can be easily mixed on the rig sites with much less hazardous effects compared to OBM. Base oil with high aniline point can be detrimental to elastomers, causing swelling and failure. Due to OBM’s low conductivity it can lead to poor log quality. Since the initial trial that was conducted in 2016, several wells have been drilled using High Performance Water Base Drilling Fluids and the Customized HPWBM. The performance of the fluid system matches that of the OBM. It has been used in different fields in North Kuwait (NK) and South East Kuwait (SEK), in different formations with minimum and maximum stress direction in different inclinations from 0 to 90°.
In most cases, the customized fluid met set KPIs, making it an environmental and performance driven alternative to OBM, eliminating the environmental impact and cost of disposing of cuttings.
“Baker Hughes Drilling and Completion Fluids Product line is very grateful to Kuwait Oil Company for the trust bestowed upon us as a valued business partner and will continue to deliver to their expectations with introduction of solutions to achieve operational excellence, improve productivity and minimize impact to the environment,” says Prakash Jadhav, Baker Hughes Service Delivery Manager. “We also look forward to collaborating on “GO GREEN” initiates to take this eco-friendly drive in KOC operations.”
