Saudi Aramco is developing gas fields in various areas utilizing vertical and horizontal wells with rotary as well as motor BHAs. This application requires Saudi Aramco to drill laterals through an extremely tight sandstone formation with inclination varying anywhere from 72° to 90°. The highly abrasive formation is causing inconsistent PDC bit performance while drilling the 5 7/8-in. horizontal section resulting in exceeding the authorization for expenditure (AFE) of the wells. Saudi Aramco, in collaboration with the bit company, analyzed the field data, which showed extensive cutter damage, with abrasive wear being the most common dull characteristic. The cutter wear was causing short runs and frequent trips to change out the bit. A step change in bit design was required to extend bit life and increase rate of penetration (ROP) in areas where poor drilling performance is expected. The fixed PDC design creates an inherent limitation because only a small portion of the cutter contacts the formation, and drilling efficiency declines as the cutter wears. The resulting wear flat generates a high degree of frictional heat, which can break the diamond-to-diamond bonds in the cutter diamond table and lead to accelerated cutter degradation. An R&D initiative was launched to investigate different methods to enable a PDC shearing element to fully rotate while drilling to increase overall cutting efficiency and bit life. Several different retention methods were investigated, and a specialized fixed housing that is brazed into the bit blade was developed. The rolling cutter assembly has essentially the same outside diameter (OD) as a standard PDC cutter, which helps maintain design flexibility and cutter placement options. The newly designed 5 7/8-in. PDC was manufactured with strategically positioned rolling cutters and was run in a gas well. The objective was to achieve an average ROP of 4.7 ft/hr and drill a minimum of 240 ft of lateral hole section to achieve proposed 5% reduction in cost-per-foot. The bit achieved a record ROP of 14.85 ft/hr while drilling 527 ft of the abrasive sandstone formation. After achieving positive results from tests in lateral sections, the new bit design was also tested in a two vertical sections through the same tight sandstone formation on rotary assemblies. In these applications, the new bit design performed better than those in offset wells, with one of the two drilling from shoe to shoe for the first time in that field. This paper will discuss the application and evolution of rolling cutter bits, along with the results achieved by bits fitted with these cutters in Saudi Arabia.
Inconsistent roller cone/PDC bit performance drilling horizontally through the hard/abrasive Granite Wash reservoir in western Oklahoma has resulted in low ROP, increased operating days, and escalating drilling costs. The difficult Marmaton age wash formation is encountered at 11,000-13,000ft TVD and has unconfined compressive strength (UCS) in excess of 30,000 psi. The typical well requires drilling a curve to horizontal, then 4,000 ft of 6-1/8-in lateral borehole. Offsets analysis revealed that 1-4 RC/PDC bits are required to drill the curve in addition to 1-13 bits to finish the lateral. The operator required a technological solution to minimize bit consumption/trips to lower well construction costs while achieving directional requirements. An analysis of the most troublesome wells was conducted and a mathematical-based predictive analysis software identified the changes required to efficiently deliver the directional objectives. The study indicated that using a 4¾-in high-power steerable turbodrill, with two bends and a specific stabilization setup coupled with an application-specific 6 1/8-in diamond impregnated bit would significantly increase BHA performance and enhance section economics. The operator's drilling team studied the recommendation and concluded the BHA had the potential to increase reliability and reduce operating costs drilling the difficult Marmaton Wash. This new turbodrill/impregnated bit BHA was run in several Washita and Beckham County wells with outstanding results. In one well the BHA drilled 4,040ft of 6 1/8-in lateral hole section in a single-run saving the operator eight drilling days and $348,000USD vs plan. The assembly required steering only 17% of the time. The borehole was completed in 589hrs at an average ROP of 6.9ft/hr. This performance set several new world drilling records. The authors will present case histories that illustrate performance achievements in the horizontal section and provide details that contributed to the success of the unique BHA.
Many companies are using product platform concepts to gain economies of scale and to identify new market opportunities. Though the area of product platforming continues to be actively investigated by both industry and academia, there is no comprehensive classification scheme that can provide a clear picture of the existing problems and possible future research directions. Hence, in the present paper, we introduce a broad taxonomy that classifies product platform problems based on the product development stages. This can serve as a basis to: (1) Extract and categorize problems from research literature; (2) Identify potential extensions and/or new problems that have not been addressed in the literature; and (3) Identify existing problem sets and/or develop new problem sets for benchmarking purposes. We introduce a Conditions and Assumptions Code (CAC) scheme and use it in the identification of benchmark problems as well as in analyzing two classes of evaluation methods adopted for the platform problems: metrics-based and optimization-based. Thus, we have not only categorized existing problems but also identified possible future research problems in each of the categories. This categorization serves as a navigation tool to understand the progress made in this field so far and to identify new research directions.
This paper presents the status of an ongoing project to develop a comprehensive suite of test problems suitable for comparing methods for scale-based product platform design. Despite a growing body of work in the area, there is no adequate set of testbed example problems for product platform design and benchmarking. A lack of consensus as to exactly what scale-based platform design entails has also hampered comparison of methods. In order to make a comprehensive test suite, we first need to define what different capabilities of platform design methods should be tested. To further this end, a classification scheme for example problems for scale-based platform design is presented. This simple taxonomy classifies example problems on the basis of two criteria: selection of platform architecture and incorporation of market demand. A brief review of examples from the literature shows that the existing examples are useful to test only a few of the capabilities of platform design methods. A new extension of an existing example, the design of a family of universal electric motors, is presented to test capabilities not covered by the existing set. This extended example is the first in our suite of examples.
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