The collaborative approach used for cementing the production liner in an onshore development well in Russia is presented. The reservoir has a narrow window between pore and fracture pressures, which has previously caused formation instability and severe lost circulation issues during well construction, compromising zonal isolation objectives. Total loss of fluids experienced while cementing the 114.3 mm production liner in the first appraisal well in the field led to revising the cementing strategy. Collaboration among various parts of the drilling department and the opportunity to define a new approach resulted in a decision to introduce managed pressure drilling (MPD) to address the challenges associated with a narrow pressure window and uncertainty in pore pressure while drilling and cementing. This enabled implementing the optimal mud weight and adjusting equivalent circulating density (ECD) during cementing with minimum overbalance. Reducing the mud weight from 1.20 SG to 1.05 SG eliminated losses after running the liner and while cementing it. As a result, pre-job circulation rates and pumping rates during cementing could be increased, improving mud removal efficiency and achieving top of cement at the required depth. The constant-bottomhole-pressure mode of MPD was used to maintain the same ECD during displacement of the well to a lighter fluid and during cementing, avoiding well influx during pumpoff events by compensating for the annular friction pressure loss with surface backpressure. This first onshore managed pressure cementing operation executed within the same field in Russia (later named as field A) was completed flawlessly, with no safety or quality issues, zero nonproductive time, and achievement of the required zonal isolation across the challenging production section. The collaborative approach used was a novel strategy, with the mud weight program strategically adjusted before and during the cementing operation to achieve zonal isolation objectives.

This technical paper provides the result of utilizing MPD technology for drilling and cementing a 127 mm production liner withing the Zadonian horizon D3zd in an exploratory well of the Prohorovskoe field. The previous wells drilled with a conventional approach in the field had complicated issues such as circulation losses and well control. It was complexified with high hydrogen disulfide concentration in reservoir oil which was a health hazard to a site personnel. As a result, to eliminate all complications, resources and operational time were needed. To prevent and eliminate complications in a long wall, core drilling and well completion, managed pressure drilling (MPD) and cementing technology with semi-automatic control system was applied. The project is unique as such complicated jobs with the core drilling and cementing with MPD were executed for the first time in The Komi Republic. MPD approach allowed to figure out bottomhole safe conditions and maintain ECD within a required pressure window. It is necessary to notice that a part of the section was core drilled. Knowing the window between pore and fracture pressures safety limits, a run-in-the-hole design with further cementing job was optimized. The execution was done flawlessly without circulation losses and well control issues. In comparison to a previous well in the Prohorovskoe field, MPD allowed to shorten loss circulated mud volume from 2 2215 m3 to 0 m3 and avoid non-productive time. Through accomplished goals and lessons learned, new grounds to well owners and well services in a field development stage are broken.