Long-term elevated oil price stability has caused operators to apply new, high-end technology to extract bitumen from Alberta's extensive oil sands deposits (174 billion recoverable bbls). In the Fort McMurray Area, operators are utilizing a Steam Assisted Gravity Drainage (SAGD) project to get the low-gravity (≤10° API) hydrocarbons to the surface. These wells are attractive because there is no exploration risk and they typically have a 30-50 year life with no decline curve. The project requires drilling relatively shallow (500m–700m TVD) wells, but to an extended measured depth up to 3000m, through soft, yet extremely abrasive sands. The wells have high build-rates (9°/30m) and typically the horizontal section averages around 1000m but lengths can reach 2000m or more. To achieve the well profile and run-length requirements and withstand instantaneous ROP up to 200m/hr, operators were utilizing steel-tooth bits for the build sections and PDC to complete the horizontal legs. To improve economics/footage drilled in the build section, a service company has developed a new 14-3/4" (374.6mm) rollercone bit with an innovative steel-tooth cutting structure that provides extended wear resistance for drilling in these highly abrasive SAGD directional applications. The new bit features a thick application of highly wear-resistant hardfacing materials and new cone design increases gauge holding ability allowing multiple runs without going undergauge. Finally, a metal-seal provides extended bearing life by resisting accelerated wear due to the sharp abrasive sand formations. Because of the new technology, operators are getting more meterage utilizing the new steel-tooth abrasive bits compared with conventional premium milled tooth products. This allows the operator to drill up to four build sections with one new technology bit compared to only one or two hole sections with conventional bits, thereby cutting costs substantially.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe majority of the fields in southeast Mexico require 1,000m to 3,400m of 17-1/2 hole to set 13-3/8 casing at the top of Encanto/Deposito formation. Lithology is typically weak sandstone with shale stringers (UCS 2,000-6,000 psi). Operators have attempted to use PDC to drill the hole section in one run with limited success. Operators required an updated steel-tooth rollercone to cut costs by reducing trips/bits to complete the section. Examination of steel-tooth dulls indicated erosive and abrasive wear due to the high sand content was the major factor limiting performance improvement.The authors will present case studies that document the new bit design has increased meterage by at least 46%, ROP by 12%. Total bit runs have decreased from six to four and the total cone revolutions have increased by 60% compared to average values of best offset runs in several fields. This has saved the operator an average of $140,000USD per 17-1/2" hole section per well.
In several Canadian applications, operators have recognized the potential to replace standard roller cone products with a more viable solution that will drive down costs when drilling straight hole and curved sections. In these high-abrasive applications, roller cone bits are preferable because of their ability to increase ROP while maintaining a controlled direction and their relatively low price compared to polycrystalline diamond compact (PDC) bits. Typically, roller cone bits are removed from service because of damage or wear to the bearings or seals, and/or to the cutting structures. However, in these applications, the weakness occurs in the leg section.Historically, wear protection on the leg outside diameter (OD) was achieved by placing tungsten carbide inserts in vulnerable locations. Although this increased wear resistance, the softer portion of the leg OD was still exposed to the damaging effects of hole-wall contact due to the required spacing between the tungsten carbide inserts. Also, the required drill holes for the inserts could become crack-propagation points in certain drilling environments.To improve the durability of the leg while increasing seal and bearing reliability, abrasion-resistant hardfacing was incorporated onto the majority of the leg OD. Roller cone bits with the new hardfacing leg protection were field tested in several operators' wells with excellent results. The hardfacing leg protection proved to reduce OD wear more than TCI leg OD protection, therefore providing improved seal and bearing protection and thus reliability. Additionally, the hardfacing configuration stiffens the leg, increasing durability by reducing flexing and the potential of leg breakage. By preventing early bearing failure due to abrasive leg wear, this innovative technology has caused a performance paradigm shift and has significantly driven down drilling costs and non-productive time. The authors will present several case studies that document how the unique technology has increased the overall leg protection of roller cone products resulting in improved seal protection. This has led to an increase in total footage drilled in some applications and substantial cost savings to operators compared with standard roller cone products in those applications that do not have the new hardfacing.
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