The current manuscript describes the engineering approach on how demanding wells in a very challenging field have been delivered more efficiently and consistently than the norm with an increase on the footage per day KPI by more than 75%. The subject field is one of the most challenging fields in the area with issues such as: top hole's losses with risk of cellar collapse; severe wellbore instability across 16-in. hole section with nearly 40% of offset wells facing stuck pipes; reactive shales across 12-1/4-in. hole section requiring enhanced drilling fluid design; losses across 8½-in. curve section, increasing the risk of not achieving zonal isolation after the 7-in. liner cementing job. A holistic approach was developed to tackle the field specific challenges including deployment of fit-for-purpose technologies, improvement in drilling practices and a better management of the risks. The wells delivered after the Implementation of this approach were drilled faster by up to 19 days when comparing with the previous drilling campaign, achieving ROP records in all the sections with significant improvement: 77% in 16-in.; 20% in 12-1/4-in.; 50% in 8-1/2-in.; and 60% in 6-1/8-in. The results can be taken as lesson learned when facing such challenges and be implemented in similar wells in Middle East and worldwide alike.

Enhancing drilling performance for surface sections across multi-layer formations is relatively challenging in the Middle East due to the carbonate's soft nature combined with interbedded formations resulting in lost circulation, harsh drilling environment leading to shock-and-vibration behaviors, and bit/BHA damage; factors including bit size and applied drilling parameters affect these conditions. This manuscript demonstrates the study and successful field application performed on different approaches, including bit/BHA selection, hydraulics enhancement, and drilling fluid recipe. Firstly, by lowering Total Flow Area (TFA), hydraulics analysis demonstrated an increase of Horsepower per Square Inch (HSI) and Jet Impact Force (JIF) by up to ~28% compared to the existing current designs. Furthermore, the advantage of the partially hydrolyzed polyacrylamide (PHPA) additive for the Mix on Fly (MOF) recipe is valuable as a lubricant shale inhibitor, sealing microfractures and coating shale surfaces with films retarding dispersion and disintegration. Hence, reducing torque and friction and minimizing shock-and-vibration behaviors. The BHA was engineered and redesigned in order to increase WOB limits and reduce building tendency. Additionally, bit selection was accomplished from IADC 435x to IADC 425x to optimize the ROP and durability. Improvement results have been observed while drilling the section in one run (shoe to shoe runs) without any wellbore instabilities and bit/BHA damages. The BHA has maintained the hole angle from deviation. For instance, the Gyro logs showed that the maximum inclination of the wellbore was less than ~1.5 degrees. Additionally, the BHA higher WOB was applied on thicker shale layers, indicating a higher performance once applying higher WOB. Ultimately, due to the PHPA additive on MoF, a smooth trip out of the hole illustrated that the hole was in good condition, eliminating the wellbore instability risks and the wiper trip. Moreover, the shocks and vibrations were reduced considerably based on the nearby offset. In addition, a new record for enhanced drilling ROP of 43.83 FPH was achieved. Showing illustrated improvements with an increase of ~35% compared to offsets of 22in section across that formation interval. Indeed, TCI 425x bit established a higher durability during this drilling run with medium dull grading compared to 435x, where it had to POOH for bit damage. This led to reducing the section's time by 0.75 days compared to the operator's existing best performance time of the offset wells in that field. This manuscript offers engineered key solutions to numerous challenges encountered across various surface sections relying on the well types while drilling with full circulation or lost circulation across the formation compositions such as but not limited to Anhydrite and Shale. The outcomes could be extended as lesson-learned for such challenges and easily implemented considering full risk assessment for drilling wells in the Middle East and Worldwide to illustrate similar advantages.

A sour carbonate reservoir has been identified for water flooding to improve hydrocarbon recovery. The field is situated in the South of Oman and was discovered by PDO in 2005. Production began in 2007 and contains crude oil with 30° API oil gravity and solution GOR of 80 Sm3/m3, as well as, sour fluid contaminants of 5 mol% H2S and 3 mol% CO2. Reservoir water fluid samples confirm salinity is more than 220,000 mg/L chloride ions. While the reservoir is over-pressured at more than 600 bara with a bubble-point pressure of 140 bara, reservoir pressure continues to decline during the initial depletion phase of the field development. Although water flooding will arrest pressure decline in the reservoir, due to subsurface challenges and uncertainties, artificial-lift is considered a key project requirement during the expected field life. Initially, reservoir water salinity is expected to contribute to an increased risk of salt precipitation and related flow assurance concerns as the water flood approaches the production wells. In addition, expected producing conditions are considered to be extremely corrosive. This paper will provide a summary of the expected field conditions, water flood project background and key artificial-lift application challenges including the proposed conceptual well completion designs to support the field development. A summary of artificial-lift selection, design and implementation strategy will be explained including objectives, scope and results of the recent jet-pump field trial. Finally, a brief summary of the key conclusions and plans forward will be shared.

Well construction process through the unstable formations prone to total losses, pack-off and water influx is challenging. The manuscript describes the casing while drilling (CwD) combined with stage-cementing tool as introduced solution, when the challenge was to ensure that torque limit is not reached while drilling and estimate the effect of CwD on curing total losses and bring the casing while drilling performance to the level of conventional drilling. Introduction of CwD required extensive study of the potential torque while drilling as existing stage-cementing tools have low torque rating. Additionally, the casing fatigue may be a factor affecting the operations what lead to an introduction of magnetic particle casing inspection. The CwD bit design was adopted to the geological conditions based on best performance of the PDC bit, and originally selected drilling parameters were further optimized based on the result of the first runs. As the drilling of the well required utilization of mud cap for well control purposes, the mud recipes were adjusted to optimize the drilling performance and minimize the cost implication. The proposed solutions allowed to eliminate the problem with wellbore instability and related stuck pipe events. Further the proper engineering of the drilling process allowed significantly increase the rate of penetration since the beginning of the implementation, when the drilling torque never reached the limit even at 7,000 ft depth. The manuscript describes in detail the approach to make a proper design of CwD process focusing on prevention of existing problems and aiming to convert mitigation tool to a performance tool. Additionally, in details described the studied effect of CwD on curing total losses in highly fractured environment.

Drilling the 12.25-in. landing section in one of the Middle East fields had been a challenge in terms of drilling performance due to combined downhole severe drilling dynamic mechanics effects and borehole instabilities. These complications eventually lead to downhole tool failures and a low rate of penetration (ROP). This manuscript describes the solution to introduce tandem downhole dynamic recording tools in the Bottom Hole Assembly (BHA) which provides a better understanding of the downhole dynamics and mechanics effects guiding to optimum BHA design and leading to better performance. Drilling the curve and landing section is challenging due to extreme stick & slip (S&S) and shocks & vibrations (S&V) phenomena resulting in low performance and difficulties in achieving the directional requirement. The 12.25-in. landing section is drilled with a full set of Rotary Steerable System (RSS) drive, Positive Displacement Mud Motor (PDM), Measurement While Drilling (MWD) and Logging While Drilling (LWD) tools, making the BHA very rigid. Nevertheless, many initiatives have been carried out to enhance the BHA and bit design with limited improvement. After performing a detailed risk analysis, tandem downhole dynamic recording tools were introduced to understand the downhole dynamics behavior and the interaction between the bit, the drilling BHA components, and the different formations drilled. The downhole dynamic recording tool is powered by batteries and records the data in memory mode for post-run analysis. It measures downhole drilling mechanics with its three-axis accelerometers, gyro, and temperature electronics along with other measurements. The downhole recording tools was installed tandemly across the 12.25-in. motorized RSS BHA where one tool was positioned inside the bit and another one in a sub above the mud motor. After the run, all the data from the two downhole recording tools were downloaded and then analyzed. From the recording tool at the bit, it can be concluded that the PDC bit used in the analyzed run, generated low-to-medium stick & slip, hence, a new bit design with more aggressive features could be used safely to enhance the ROP. From the recording tool in the sub above the mud motor, it was concluded that the BHA components and mainly the LWD tool created high-to-severe stick & slip due to its stabilizers, and action should be taken to minimize this effect. In addition, the drilling fluid lubricity needs to be enhanced to reduce the stick & slip and shocks & vibrations effects on the tools. All the presented solutions and lessons learned of the downhole dynamic recording tools utilization can be used for future run enhancement and to be replicated worldwide as applicable.