Pit Less Drilling Significantly Reduces Wells Environmental Footprint
Authors: Faisal Rahbi , Hafidh Naamani , Mahmood Sa'idi , Ahmed Ghafri , Donald R. Smith 
Published: November 2024

Pit less Drilling technology is a technology that eliminates the requirement for earthen pits or sumps to capture waste fluid. In this paper we will examine how pitless drilling technology, when applied properly, can optimize drilling operation efficiency, drilling fluid medium while simultaneously significantly reducing the environmental footprint of the drilling operation. The benefits derived from pit less drilling are numerous ranging from its primary function of improved environmental stewardship, to site safety. Additional benefits of pitless technology directly relating to reduced costs, improved overall drilling efficiency, and improvements in wellsite safety will be examined and detailed in this paper.

A Pit less drilling package must be capable of simultaneously providing multiple tasks, with on-going drilling operations. These features or tasks include active system fluid processing while drilling, maintaining clear water during drilling when required, dewatering of drilling fluid during drilling or end of hole (EOH), oil base mud (OBM) processing, OBM cuttings processing, and barite recovery operations. The system should integrate seamlessly into the drilling rig and be capable of rigging up and down within the time frame constraints of the rig's own rig up/down operations. Additionally, the Pit less drilling system must offer redundancies in its design so that drilling operations are not impeded, should some element of the pit less drilling system fail while operations are on-going.

During the respective three well trials, an integrated pit less drilling system along with additional support equipment was paired with select drilling rigs operating in various fields.

There was a significant learning curve for drilling personnel at the start of each trial which impacted results on the initial wells in each trial phase. Despite the lack of experience of the rig crew with pitless operations, the pitless operation was successful in "Zero discharge" of water or cuttings to the pits in both trials. As rig personnel became more familiar with the pitless drilling requirements, significant improvements in overall rig performance were noted and are detailed in this paper.

Water based drill cuttings were initially captured & stored in containment bins during each section of hole drilled and then transferred to disposal after drilling operations ceased. Significant reductions of more than 85% in water usage was evidenced. Water was recycled and reused as much as five (5) times during each well event. Lab results of the EOH water indicated no adverse changes in the water properties. Improvements in drilling performance were also evidenced. Low gravity solids were maintained at optimum levels when the centrifuge support equipment was on-line for the drilling operations.

This paper will examine and analyze recent results from the trial conducted in the Field B area of Sultanate of Oman in 2021, combined with results from a previous trial conducted in 2017 in the Field A/B area.