Drilling reservoir section in the oilfield located in Far North region is challenged with high risks of mud losses ranging from relatively minor losses to severe lost circulation. Numerous attempts to cure losses with traditional methods have been inefficient and unsuccessful. This paper describes implementation of Managed Pressure Drilling (MPD) and Managed Pressure Cementing (MPC) techniques to drill 6-1/8″ hole section, run and cement 5″ liner managing bottomhole pressure and overcoming wellbore construction challenges. Application of MPD technique enabled drilling 6-1/8″ hole section with statically underbalanced mud holding constant bottom hole pressure both in static and dynamic conditions. The drilling window uncertainty made it difficult to plan for the correct mud weight (MW) to drill the section. The MW and MPD design were chosen after risk assessment and based on the decisions from drilling operator. Coriolis flowmeter proved to be essential in deciphering minor losses and allowed quick response to changing conditions. Upon reaching target depth, the well was displaced to heavier mud in MPD mode prior to open hole logging and MPC. MPD techniques allowed the client to drill thru fractured formation without losses or gains in just a couple of days as compared to the months of drilling time the wells usually took to mitigate wellbore problems, such as total losses, kicks, differential sticking, etc. This job helped the client to save time and reduce well construction costs while optimizing drilling performance. Conventional cementing was not feasible in previous wells because of risks of losses, which were eliminated with MPC technique: bottomhole pressure (BHP) was kept below expected loss zones that provided necessary height of cement and a good barrier required to complete and produce the well. Successful zonal isolation applying MPC technique was confirmed by cement bond log and casing integrity test. Throughout the project, real-time data transmission was available to the client and engineering support team in town. This provided pro-active monitoring and real-time process optimization in response to wellbore changes. MPD techniques helped the client to drill the well in record time with the lowest possible mud weight consequently reducing mud requirements. The MPD system allowed obtaining pertinent reservoir data, such as pore pressure and fracture pressure gradients in uncertain geological conditions.

While drilling well in the Pre-Caspian basin, a presumably technogenic nature zone of influx was exposed, which did not fit into the model of the geological structure of the section. Attempts of influx management were unsuccessful. The well had to be abandoned without reaching the target. This article describes the experience of Managed Pressure Drilling and Cementing technologies deployment, process features and equipment hookup in unconventional wellhead configuration and Slim Drill type of rig. Application of MPD technology made reaching target depth successful in the condition of constant water influx. Drilling proceeded in complicated geological conditions: simultaneous crossflow between influx and losses zones, as well as drilling mud gradual replacement by formation fluid. Bottomhole pressure was controlled by Surface Back Pressure made by MPD choke and sealed wellhead using a Rotary Control Device (RCD). The compact set of MPD equipment was rigged up as ergonomically as possible due to space restriction of slim hole drilling techniques. The MPD technology made it possible to complete the construction of the section without curing losses and weighting the drilling fluid up to control technogenic influx, safely and effectively control bottomhole pressure and achieve geological targets. MPD tests were performed at various depths to determine formation pressure and formation integrity, which made it possible to determine the drilling window for successful construction of the section. After finishing drilling, a pull out of hole and well logging was carried out in an open hole on a drilling pipe with pressure control, which was previously impossible due to the high intensity of influx. Running 4-1/2" (114 mm) casing with pressure control, as well as cementing in MPC mode were applied. The surface backpressure was gradually reduced during cementing as heavy cement was pumped to minimize the risk of cement loss while controlling formation fluid influx. As a result, cement was lifted through the annulus to the wellhead, which finally eliminate the complication associated with the presence of incompatible zones of loss and influx, and to eliminate behind-the-casing flows. The economic feasibility of well construction was maintained by set of equipment adapted to non-standard conditions The first application of MPD technology on the Slim Drill (small-sized drilling rig) project successfully revitalized previously abandoned well. It shows the validity of using MPD technology by the help of optimized set of equipment. The work reveals broad prospects for replication on a previously inaccessible wells due to economic reasons.