SPE/IADC '19: Day one presentations show wide variety of drilling-related innovation
THE HAGUE -- After the initial opening remarks from key officials, along with the keynote address, the annual SPE-IADC Drilling Conference on Day 1 (Tuesday, March 5) got down to what it does best—presentations on a wide variety of technical innovations and advancements over the last year. And from what this editor saw in different themed sessions, these presentations do not disappoint.
While it’s hard to do justice to the variety of technology in a short format, several presentations did catch this editor’s attention, and they give some of the flavor of the overall technical program. For instance, on Tuesday morning, in the “Fluids and Waste Management” session, authors from Halliburton presented a paper entitled, “Optimised Cuttings and Slops Management Help Save 250 Days on Six-Well North Sea Program.”
It seems that an operator set challenging ROP targets on a six-well campaign in the Norwegian Sea, with total depths between 6,000 and 7,000 m (19,500 to 22,750 ft) and initial targets of 70 m/hr (17.5- in. interval) and 120 m/hr (12.25-in. interval). To support these ROPs, the cuttings and slops management system needed to provide higher conveyance and storage capacities than usually observed during drilling. When the specified ROPs were achieved, targeted rates were increased on subsequent wells.
Collaboration among the operator, rig crews, and service provider was important to operating a high-volume cuttings management system. Adequate transfer and storage capabilities were essential on both the rig and vessels delivering waste to shore for disposal. On the final well, ROP targets increased to 130 m/hr (17.5-in.) and 230 m/hr (12.25-in.). Operating at 80% to 90% capacity, the system managed up to 60 mT of cuttings per hour. A total of 8,959 m3 slops was treated, resulting in overboard discharge of 8,769 m3 of treated water, and waste volume sent to shore was reduced 98%.
The drilling program was completed 250 days faster than planned, and wells were delivered for production one year earlier than planned. The reduced time allowed the operator to drill a seventh well within the original timeframe for the six-well program.
Gains from MPD usage in Argentina. Meanwhile, in the “Challenging Projects” session, also on Tuesday morning, several Petrobras authors presented a paper entitled, “Well Safety and Performance Gains from MPD in Unconventional High Overpressure Reservoirs in Argentina.” They described performance improvements and well safety achieved with the use of Managed Pressure Drilling (MPD) on two wells in the Parva Negra Este exploratory block of the Neuquén basin.
High-pressure zones characterized the drillsite, with pore pressures higher than 18 lbm/gal in unconventional reservoirs. Use of MPD in both well constructions was termed “quite efficient,” including well control and P&A applications. Those operations proved that MPD can effectively replace underbalanced drilling (UBD), which is standard practice in that area.
In the first well, Petrobras reported significant gains in drilling performance, compared to wells previously drilled. Drilling with MPD did not record NPT, differing substantially from previous wells drilled in the same area, where NPT averaged 20 days. A considerably larger recovery of coring samples was achieved, eliminating one well section. This was done by drilling two zones in a single section. Additionally, lessons learned were implemented, resulting in higher ROP with the support of MPD.
In the second well, a high over-pressurized pore zone was reached, leading to a very complex well control event, followed by a permanent P&A operation. The formation pore pressure was much higher than expected for that area. Instead of using 18 lbm/gal drilling fluid, it was necessary to weight the fluid up to 21.3 lbm/gal, adding hematite. Given that scenario, using MPD made circulation and well cementing safer than with conventional drilling approaches used in the area. Applying Dynamic Formation Integrity Tests (DFIT) and Dynamic Pore Pressure Tests (DPPT) ensured a more precise operational window, helping to formulate risk matrices for safely pulling the drilling string out of the hole.
Besides performing those tests, the MPD system helped to evaluate operational parameters and verify effectiveness of settlement of the abandonment cement plugs. Thus, MPD supported safer drilling and P&A jobs, better drilling performance, and greater information acquisition through more efficient well logging and sample coring.
Self-adjusting PDC bits. Finally, on Tuesday afternoon, in the “Advances in Drill Bit and Downhole Tool Technology and Applications” session, several authors from Baker Hughes, a GE company, presented findings from their paper, “Self-Adjusting PDC Bits Reduce Drilling Dysfunction, Increase Drilling Efficiency in Gulf of Mexico Wells.”
They noted that drilling interbedded formations can induce torsional vibrations that result in inefficient drilling and damage to drillstring components. A common choice for such applications is a standard PDC drill bit; however, PDC bits, due to their shearing action, often show some level of torsional dysfunction. Historically, the most effective method to mitigate torsional vibrations in PDC bits is to use fixed, depth-of-cut (DOC) control technology that restricts PDC bit formation engagement at a pre-determined ratio of ROP and drillstring RPM.
The challenge in using fixed DOC control is finding a compromise between limiting vibrations through targeted sections without limiting ROP in others. Accordingly, a self-adaptive DOC technology was developed. The technology automatically adjusts the DOC engagement threshold as drilling conditions change, eliminating manual parameter adjustment required, at surface, to manage torsional dysfunctions.
In one recent self-adaptive bit run in a deepwater Gulf of Mexico well, a 12¼-in. bit drilled past 30,000 ft, MD, in an abrasive, interbedded section. The self-adaptive bit delivered 48% improvement in ROP over the best offset, saving 23 drilling hours while exhibiting 97% smooth drilling concerning stick-slip, and 100% as relates to axial and lateral vibrations.
Another application yielded good results in a section featuring bottomhole coring. In three separate runs, the self-adaptive bit drilled a sand/shale formation with 98% smooth drilling concerning lateral vibrations, axial vibrations, and whirl. It also exhibited 97% smooth drilling concerning stick-slip.
