Notwithstanding significant advantages of the oil-base mud systems, their application inherent in a number of disadvantages that have been primarily attributable to environmental restrictions. In 2017 AKROS LLC and GAZPROMNEFT ran full-scale field-testing of potassium and sodium formate mud systems enabling them to analyze the performance of such systems and define the key application features. Conclusions on the application features of these systems and their perspectives in Russia are based on the results of the work performed.
To implement potassium and sodium formate drilling fluids in GAZPROMNEFT fields, the full-scale laboratory testing was performed. The outcomes enabled the identification of fluid formulations for field applications and procedures for the maintainance of mud properties when drilling.
Two intervals on «Gazpromneft-Khantos»' LLCs Yuzhno-Priobskoye Field and three intervals on
«Gazprom Neft Shelf» LLC's Prirazlomnoye Field were drilled with potassium formate-base formulations.
Field testing proved the high efficiency of potassium formate mud systems allowing them to:
achieve high drilling performance indicators;
gain experience in horizontal well drilling without lubricating additives demonstrating loads and torques similar to or lower than values observed in mud systems treated with lubricants;
develop the procedure for interval treatment of a high-density drilling fluid;
confirm the possibility of achieving a high density up to 1.41 g/cm3 without barite;
implement the technology ensuring mitigation of environmental risks connected with drilling fluids;
drill horizontal section and production casing intervals using one type of drilling fluid instead of two, facilitating reduced waste and prepared volumes.
The potassium formate mud system proved to be efficient and has impressive perspectives in Russia as an alternative to oil-base drilling fluids, particularly for high formation pressure drilling. Based on field application results, practical application procedures and optimum recommendations for controlling mud properties were developed. Comparative tests for inhibition effectiveness, reducing friction factor, achieving high drilling performance were conducted.