This document presents the successful application of pro-active Managed Pressure Drilling (MPD) to drill one section through three different sands; the one in the middle with a low fracture pressure, the lower sand with a formation pressure higher than the frac gradient of the weak formation. The wrong decision to apply MPD in a reactive way leads to NPT, influxes, mud losses and increased risks. It is shown how the conventional procedures to drill and make the trips are replaced by tailored MPD procedures leading to successful results. The Client understands the high value of proactive MPD, not only to drill but also to during trips. The drilling commenced with a MW of 1.6 g/cc and after 100 m the MW was increased to 1.62 g/cc (it is a routine procedure in the field to increase the mud density prior to reaching the expected high pressure zones while drilling conventionally). Some meters after start drilling the low frac gradient sand total mud losses were observed. The MW was reduced from 1.62 to 1.52 g/cc and MPD was implemented in a proactive manner whereby the BHP was maintained constant. The big challenge was to control the well at all times avoiding a catastrophic condition.
The complexity of drilling highly deviated wells in Kuwait drives the need for step changing in the well construction mindset, where severe to complete loss of circulation in Shuaiba formation significantly deteriorate the shale layers in Wara and Burgan formations leading to uncontrolled wellbore stability events. Casing while drilling (CWD) and two-stage cementing with a light density cement slurry were introduced as a technology system to drill the highly deviated complex wells through unstable and highly fractured formations. Fit for purpose engineering processes, advanced software solutions, a tailored bit and a bottom hole assembly dynamically simulated for drilling stability and directional tendency behavior were designed. A special light density cement slurry with high compressive strength was also designed to tackle the lost circulation issues when cementing the casing string. The paper will describe how the technologies can work as one system to solve complicated wellbore problems and address the problematic challenges of drilling unstable shales and fractured formations in the same section of the wellbore. This strategy enabled a significant time saving compared to drilling the section conventionally, removing Non-Productive Time (NPT) resulting from additional trips, cement plugs, stuck pipe, and subsequent sidetracks.
A new cutting element technology bit along with new drilling automation software provides a solution to drill the challenging 12 ¼" section in two fields in Northern Kuwait. The 12 ¼" section was drilled using directional BHA building the angle between 25 to 30 degrees. The formations are characterized to be interbedded limestone and reactive shale causing high downhole vibrations, high torque and stick and slip which affects the buildup capability of the directional tool and overall performance in this section. The main objective is to improve drilling performance by developing an integrated solution to eliminate the downhole tool failures and increase the rate of penetration. The engineering team incorporated a unique geometry into the bit cutting elements design and developed the Ridged Diamond Element (RDE) bit which has new cutting element technology and different geometry than the standard PDC cutters. The ridge shape cutter face helps to reduce the reactive torque generated through the cutter face. The ridge shape cutter face also helps in improving rate of penetration (ROP) by efficient rock removal. With regards to the drilling automation software, the objective is to determine (through the analysis of surface data) the best drilling parameters of RPM/WOB to achieve the maximum ROP for each formation while at the same time detecting and mitigating drilling dysfunctions such as shocks, vibrations and stick slip. The system was operated in advice mode as it will be explained more in detailed throughout the paper. Torque reduction system technology was used to reduce the surface torque variation and reduce the stick and slip by instantaneously altering surface string rotation (RPM). The new cutting element technology in combination with the drilling automation software provide an integrated solution to the challenges faced in the drilling operations for this 12-1/4" hole section. On the first test well, RDE bit and the drilling automation software were used with a motorized rotary steerable system (RSS), to drill 1,060 feet in 15.27 on-bottom hours with an effective ROP of 69.4 feet/hour. The second test well was in a different field, drilling 1,265 feet in 25.22 on-bottom hours achieving ROP of 50.16 feet/hour. Both test runs set new benchmark performance in comparison to the respective field offset wells. This high performance seen in both test runs were enabled by increase in ROP & the significant reduction of downhole vibrations and stick and slip brought by combining the new technologies in bit and drilling automation software. The first-time application of the new technologies helped the operator to solve drilling challenges, increasing performance and reducing the cost per foot by 20%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.