Advanced Technology Improves Drilling Economics/Sets New Benchmark, Southeast Mexico
Abstract: 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-t… Show more
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Cited by 4 publications
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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.
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.
Step Change in Performance: Upgraded Bit Technology Significantly Improves Drilling Economics in GOM Motor Applications
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWith vast regions of the Gulf of Mexico (GOM) rapidly becoming mature provinces, operators are constantly looking for ways to systematically reduce the costs of drilling development wells, especially with improved technologies that deliver reliable performance and decreased risk.The application of a new steel tooth rollercone bit with a technically advanced metal seal bearing has achieved this goal and is having a significant impact on drilling economics in the GOM. Improvements in bearing life, seal reliability and cutting structure durability have resulted in more time on bottom, thereby giving the operator the confidence to apply the new rollercone bits in long directional hole sections. Most of the wells drilled are directional, and heavy water-based drilling fluids are often required in the intermediate hole sections; heavy synthetic muds are sometimes used deep in the wellbore. Relatively high bottomhole temperatures combine with extremely high bottomhole pressures and balling shales to present a challenging drilling environment. Operators strive to increase rate of penetration, maximize hours on bottom for each bit, reduce risk, and complete the section with fewer bits to reduce the number of trips.The bit development phase consisted of a thorough analysis of field application data, along with rigorous forensic examinations of representative dulls from around the world to identify the downhole conditions and sealed bearing wear mechanisms that limited the current metal sealed bit life. A host of design and material improvements were conceived and developed to deliver an improved metal sealed bearing with significantly longer life and higher reliability.The improvements included metal seal surfaces up to 20% wider; a proprietary wear resistant surface on one seal face that greatly reduced both the seal wear rate and the coefficient of friction; improved back-up ring geometry and gland; and design features that enable more consistent manufacturing assembly processes to be utilized. The new rollercone bearing package proved to deliver unequaled life and reliability in high rotary speed drilling applications, superior to all current rollercone sealed bearing systems.The new steel tooth bit's long life, resistance to balling in water-based muds, highly steerable characteristics, and ability to be combined with various hole-opening systems make it the bit of choice for many GOM applications. The authors show actual GOM performance data of the new bits achieving an 80% reliability of nearly 700,000 total bit revolutions (TBR), compared to existing technology bits at less than 400,000 TBR. Specific case studies show examples of one new style bit replacing two to three current technology steel tooth bits, effectively doubling the footage drilled and TBR in the process. Another example shows 1 of the new technology bits replacing two current technology steel tooth bits with associated substantial cost savings due to higher ROP's and less flat time due one less trip...
Approximately 90% of the large diameter holes in Australasia (Indonesia, Australia, PNG and New Zealand) are drilled with steel tooth roller cone bits. A new steel tooth bit design has proven to significantly improve the drilling economics in these applications. This paper describes the drilling challenges posed by these applications, details the new bit design features, and presents case studies showing the performance improvements these new bits provide when compared with conventional steel tooth bits. The new design bits feature a novel cutting structure with pyramid-shaped teeth, additional rows of teeth, wide grooves between rows, anti-tracking row(s) with tight pitches, thick hardfacing deposits, and a bar trimmer type gauge design. The result is a steel tooth bit that delivers significantly higher ROP and longer life than current designs, with high reliability, and predictable steering behavior for directional applications. Hole sections can often be completed with fewer bits, which further improves drilling economics. These bits achieve ROPs faster than even that of large diameter PDC bits in the Australasian applications, thus the reason that steel tooth bits are primarily used. An operator in Balikpapan, Indonesia drilled a long S-shaped hole with a new 17 1/2-in. steel tooth bit at 40% higher ROP than the best of nine direct offsets that were drilled with conventional steel tooth bits. Another operator offshore Western Australia conducted a head-to-head comparison of a new 16-in. steel tooth bit against a conventional steel tooth bit in identical hole sections. The new bit drilled over 70% faster and over 25% farther than the regular bit. A third operator in the Northwest Shelf area off Western Australia employed a new 17 ½-in. steel tooth bit to complete a section normally drilled with 12 ¼-in. PDC bits. The new steel tooth bit drilled over 25% faster than the fastest PDC offset run. Additional case studies will be presented further documenting these positive field results. Introduction While PDC bits continue to replace many traditional tungsten carbide insert (TCI) roller cone bits in medium hard to hard formation drilling applications, steel tooth (ST) bits have maintained a relatively constant share of certain hole sections, such as large diameter (typically 16-in. and larger) surface holes, and intermediate sections with water-based mud (WBM) and sticky shales. This holds true in Australasia, where approximately 90% of large diameter holes are drilled with ST bits. One reason these large ST bits have retained their share of these drilling applications is the continued improvements in bit technology and performance, as described below. Improved ST bits with a novel single energizer metal seal (SEMS) bearing were introduced to the industry in 1998, and have since migrated to drilling basins around the globe.1–7 A step change in bit life and reliability was realized over former elastomer-sealed roller cone bits, with operators routinely achieving runs up to twice as long, particularly at higher RPMs (175 - 275 RPM). The new SEMS bits proved to maintain their typical bit life and reliability at elevated rotary speeds, while elastomer sealed bits tended to experience reduced seal life due to accelerated seal wear rates when rotary speeds exceeded 200 RPM. Another step change improvement in bit life and seal reliability was realized in 2005, when a second-generation single energizer metal seal system (SEMS2) was introduced to the market.8,9 This long-life, high-reliability, high RPM-compatible sealed bearing system provides a suitable platform from which to launch improved ST bits for many markets worldwide.
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