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.

Drilling surface 16-in. and 12.25-in. sections in Middle East often accomplished by complete mud losses where downhole dynamic changed completely. To increase the performance and reduce drilling time the Positive Displace Motors (PDM) are used, however drilling under complete mud losses scenario may lead to a failure of the PDM, Measure While Drilling (MWD) tool, jar and any other components of the Bottom Hole Assembly (BHA). This manuscript describes the study of BHA dynamic in total loss scenario aiming to increase Rate of penetration (ROP) and decrease mechanical failures. The changing in drilling dynamics under complete mud losses increases the severity of shock and vibrations (S&V), BHA whirl and, consequently, leads to downhole failures. Local practices have been used to control this risk by taking an over conservative approach, limiting Weight on Bit (WOB) and Revolution per Minute (RPM) to very low levels, affecting overall performance. To comprehensively understand the level of shock and vibrations under complete mud losses based on the modeled data, a Downhole Mechanics Measurement (DMM) system was used in the BHA to acquire the required data in real time to confirm and further improve the modeling of drilling dynamics. A drilling schedule with several combinations of WOB and RPM was developed to cover the full drilling envelop. This study provided valuable understanding on the drilling dynamics while drilling under complete mud losses and allowed to clearly define the limiting boundaries to optimize ROP without jeopardizing the mechanical integrity of the BHA, particularly the PDM and drilling jar. On each formation drilled, RPM, WOB were changed to cover all possible combinations and, using the continuous real time measurement, ROP was optimized based on the level of shocks and vibrations experienced. Furthermore, the recorded mode Low and High-frequency data enabled to model the drilling dynamics and to quantify the effects of shocks and vibrations on the BHA. As a result, the wells have been drilled with significant ROP improvement (saving one day per run) and without downhole failures, achieving higher than expected performance results.

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.