In Kuwait's largest reservoir, the Burgan Field, exploration wells have large potential for drilling optimization and savings; specifically a 22 inch hole, that is drilled conventionally using multiple roller cone bits in multiple trips through challenging inter-bedded formations. Hybrid drill bit technology, roller cone combined with Polycrystalline Diamond Compact, was introduced in search for an economically viable solution to deliver wells faster and achieve yearly operator targets. This paper analyzes the breakthrough drilling performance achieved by a 22 inch hybrid bit in comparison to conventional roller cones offsets and provides conclusions on economic viability. The main challenges drilling the 22 inch section are drill bit durability and drilling vibrations through inter-bedded formation layers of limestone, shale and sandstone. In addition to curing fluid losses in certain porous formations that negatively affect Rate Of Penetration (ROP). Typically two roller cone bits are used on rotary drive to drill this section at 15 feet per hour, consuming seven drilling days. Using Polycrystalline Diamond Compact (PDC) bit with a performance motor to increase ROP performance is not an economically viable solution. Using hybrid drill bit on rotary drive combines the benefits of PDC blades' durability and higher cutting efficiency with the cones' stability by grinding and gouging into the formation. The deployment of the hybrid technology was a collaboration project between a national oil company and a major oil services company. The teams focused on optimizing the complete drilling system including the bottom hole assembly, hydraulics, drilling parameters and geological factors to match the hybrid drill bit mechanism. The hybrid design selection and drilling optimization resulted in a 142-percent ROP improvement from offsets average performance. The hybrid designs consistently drilled the 22 inch hole after casing shoe to section total depth at 31 feet per hour, using one bit, in three drilling days in comparison to seven days average performance. The total operator savings from e section was approximately USD 175,000 in the first deployment. The second and third deployments established performance consistency. Such remarkable economical savings and technical optimization proved that the hybrid technology is the viable solution for two prolific exploration applications.
The 16′ Vertical Performance Motor Section is the most challenging section in Exploration Deep Drilling in Burgan Field & All South East Kuwait. The section comprises drilling hard and abrasive Zubair formation followed by reactive Ratawi Shale formation. Several technologies were introduced during the last ten years in search of an economic solution to deliver this section safer and faster with limited success. The objective of this paper is to present the process and technology implemented to drill Zubair and Ratawi Shale formations in two different wells with the same bit at record rates of penetration. Bit durability is generally the main driver in the 16′ section performance. Historically, one to two polycrystalline diamond compact (PDC) bits were utilized in this section and were pulled out for low penetration rates. The new solution required a thorough offset data analysis, including formation porosity, rock strength and abrasiveness analysis, applied drilling parameters and Mechanical Specific Energy (MSE) analysis using software. A customized PDC bit design was then developed using a state of the art bit/formation interaction model combined with an advanced cutter technology and hydraulics pairing for ultimate cutter cooling. The new PDC bit design and the implementation of the softwares used to analyse offset wells drilling parameters and rock mechanics had a significant effect on the bit durability and Rate of Penetration (ROP). The optimized drilling parameters applied as per the former set roadmap aided in managing the bit cutting structure through Zubair and Ratawi Shale formations and the bit was pulled out in re-runnable condition with a new field ROP record. The same bit was then used again in different well and drilled Zubair and Ratawi Shale formations and pulled out with 1, 3 dull condition. Over the two wells drilled, the optimized drilling plan saved National Oil Company over US $200,000, reducing the cost per foot (CPF) drilled by 38% over the field average CPF, increasing the ROP by 55% over the field average and drilling 69% footage more than the previous section benchmark footage. With the engineering evaluation of the offset data and the utilization of the new bit design, National Oil Company managed to drill Zubair and Ratawi Shale section in two different wells with the same bit for the first time and was able to improve drilling efficiency and cutting the drilling cost by eliminating bit trips and cost of new PDC bits.
In Kuwait's largest reservoir, the Burgan Field, exploration wells have large potential for drilling optimization and savings; specifically a 22 inch hole, that is drilled conventionally using multiple roller cone bits in multiple trips through challenging inter-bedded formations. Hybrid drill bit technology, roller cone combined with Polycrystalline Diamond Compact, was introduced in search for an economically viable solution to deliver wells faster and achieve yearly operator targets. This paper analyzes the breakthrough drilling performance achieved by a 22 inch hybrid bit in comparison to conventional roller cones offsets and provides conclusions on economic viability. The main challenges drilling the 22 inch section are drill bit durability and drilling vibrations through 2,000 ft. of inter-bedded limestone, shale and sandstone. In addition to curing fluid losses in certain porous formation layers that negatively affect Rate Of Penetration (ROP). Typically two roller cone bits are used on rotary drive to drill this section at 15 feet per hour, consuming seven drilling days. Using Polycrystalline Diamond Compact (PDC) bit with a performance motor to increase ROP performance is not an economically viable solution. Using hybrid drill bit on rotary drive combines the benefits of PDC blades’ durability and higher cutting efficiency with the cones’ stability by grinding and gouging into the formation. The deployment of the hybrid technology was a collaboration project between a national oil company and a major oil services company. The teams focused on optimizing the complete drilling system including the bottom hole assembly, hydraulics, drilling parameters and geological factors to match the hybrid drill bit mechanism. The hybrid design selection and drilling optimization resulted in a 142-percent ROP improvement from offsets average performance. The hybrid design drilled the 22 inch hole after casing shoe to section total depth at 31 feet per hour, using one bit, in three drilling days in comparison to seven days average performance. The total operator savings from this section was approximately USD 175,000 in the first deployment. Such remarkable economical savings and technical optimization proved that the hybrid technology is the viable solution for Burgan 22 inch application.
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