SPE/IADC Member
Abstract
An earlier macro-analysis of more than 100,000 bit records from around the world revealed that technological advancements in PDC bit design and application have contributed to a reduction in global cost per foot an average 35%, while roller cone bit performance improvements have resulted in an 8% drilling cost reduction on average. A new study of field specific bit performance and bit usage patterns further supports the results of the previous study by documenting at a micro level the impact of bit technology on drilling economics.
The impact of improvements in bit technology have significantly reduced drilling costs and increased overall drilling efficiency in both high-cost and low-cost drilling theaters worldwide. Technical advancements have improved both bit life and penetration rates.
Introduction
A number of authors have discussed on a localized and technology-specific basis the economic benefits associated with a singular advancement in the design and application of roller cone and/or fixed cutter drill bits. These and other periodically documented examinations into the relationship of bit technology advancements to lower drilling costs become even more impressive when considered globally over several decades. Kistler, et al, and Shepherd, et al, were two of the first to take a macro approach at examining the impact of advancing bit technology on lowering drilling costs.
The latest macro-level analysis revealed that the impressive performance improvements realized between 1950–1989 intensified dramatically during the present decade. The updated analysis concluded that between 1989 and mid-1995, PDC and roller cone bits were directly responsible for drilling cost reductions of 35% and 8%, respectively. When extended to 1996 (Fig. 1), the results show bit improvements continuing to drive down costs, with an updated 36% improvement for fixed cutter bits and a 9% cost reduction for roller cone bits. The indexes reflected in Fig. 1 were created by normalizing as 100 the averaged calculated cost per foot in 1989, from which the percentage annual reductions were derived.
In drawing the conclusions, the author examined bit performance from more than 100,000 bit records. The data is documented in a bit record system that contains worldwide bit rim information from every manufacturer. The large sample size eliminated concerns over potential sampling errors, thus making it possible to accurately arrive at industry-wide conclusion.
Similar results from a micro or field specific analysis are reported in a series of ease studies from the UK sector of the North Sea; the Chickadee area of Alberta, Canada; Colombia's Cusiana/Buenos Aires field; the Wamsutter area of Carbon County, Wyoming and Roger Mills County, Oklahoma in the United States.
Analytical Approach
Useful life and rate of penetration are the two performance barometers that ultimately define the degree in which a bit impacts the costs of drilling a well. Useful life is measured as footage or meterage drilled per bit; rate of penetration is feet or meters drilled per rotating hour. From an economic perspective, useful life determines the number of trips required to change out the bit. Conversely, rate of penetration directly affects the drilling hours required to complete a given hole interval. Together or singularly, these factors impact directly the number of rig hours necessary to drill a well and, hence, the costs of drilling said well.
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