This paper presents the technical development of an operator's drilling base oil produced from their MG3 plant which was evaluated through extensive laboratory studies and field trials prior to commercialization.
The base oil is based on a majority iso-paraffin component which gives an optimum kinematic viscosity, flash point and pour point for drilling applications. In addition, the drilling fluid has minimal aromatic content to fulfil international eco-toxicity standards set by CEFAS and US EPA, 821-R-11-004 Method 1619. The base oil is compatible with various oil/synthetic mud systems and additives with its low viscosity characteristic lesser than 2.4 cSt at 40 deg C which offers excellent drilling performance for Shallow and Deepwater wells. Furthermore, the base oil exhibits high flash point of more than 90 deg C to reduce potential fire hazard while drilling HPHT and ERD wells. At the same time, its superior pour point (as low as -42 deg C) suitable for storing base oil in sub-zero conditions and to be used as deep-water drilling fluid in extremely cold countries like Russia. Its unique high-performance properties provide exceptional temperature stability and optimum rheological properties throughout the extreme temperature profile of a Deepwater or HPHT well, thus resulting in a very low ECD despite drilling with high ROP.
Field trials were carried out to verify the base oil's performance under laboratory conditions. The base oil was tested as base fluid in SBM for both Shallow and Deepwater wells. The Shallow well was drilled vertically in water depth of 105M with a maximum mud weight of 14.6 PPG and bottom hole static temperature of 280 deg F. The Deepwater well was drilled vertically in water depth of 1008 M and subsequently side-tracked to a maximum inclination of 46 degree. Both wells were drilled successfully without any drilling fluid related issues as compared to severe losses experienced with respective offset wells.
A total of approximately 138 oil and gas wells were drilled by the operator utilizing their own base oil till 2018 after completing the technical evaluation in 2014. From the field trials and actual drilled wells, a comprehensive database analysis was developed for future improvisation and broader performance portfolio. The main technical challenge for the operator was to engineer a drilling fluid system with base fluid and chemical additives to obtain minimal ECD for reducing lost circulation risk. The base fluid properties are ideal for Shallow, HPHT, ERD and Deepwater applications whereby the ECD margin for Deepwater and ERD drilling is often narrow as compared to shallow wells. The successful project execution of base oil for drilling represents a significant milestone, elevating the company's base oil progress at par with other global base oil producers.