bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Drilling Strategy for PDC Bits
Authors: Wojtanowicz A. K. , Kuru E. 
Published: December 2007

ABSTRACT
A new mechanistic drilling model for PDC bits was presented. The model was fully explicit with physical meanings given for all constants and functions. The response of the drilling model to weight-on-bit and cutters removal and the stability of constants were tested using some field and laboratory data. The preliminary results were encouraging.
The concept of maximum bit performance (MBP) curve was introduced. The curves represented the maximum values of the average drilling rates for various pre-assumed footage values. In contrast to elaborate drilling models, the MBP curves are a single, comprehensive correlation representing drilling bit behavior in a formation. For calculating purposes the curves were normalized and thus they became insensitive to drillability change vs. depth as well as formation abrasiveness. The curves were plotted and analyzed for both rockbits and PDC bits. The simple method for using the MBP curves for drilling optimization was presented.
A new method for preparing a multi-bit drilling program, the dynamic drilling strategy, was developed. The dynamic drilling strategy provided the best combination of PDC bit runs to achieve the minimum drilling cost for a long borehole interval. The method was numerically compared to the conventional drilling optimization and to field practices. Considerable savings of 30% and 300% respectively were estimated.
A Comparative Analysis of PDC Bit Performance in Colorado's D-J Basin
Authors: Spradlin W. N. , Sheshtawy A. , Lohmann E. 
Published: December 2007

ABSTRACT
The following is a study of polycrystalline, or PDC, bit performance in Colorado's D-J Basin, Weld County, Colorado. Data utilized in the study incorporates over 200 bit records in the area of study, from wells drilled within the last three years. Analysis of data in the area of study is based on examination of the cost per foot drilled for each well, as well as each bit run.
Results indicate that rig efficiency has generally increased over the last three years when using either conventional or PDC bits, with the lowest cost per foot being achieved by proper application of PDC bits. A statistical difference between performance of differing types of PDC bits is noted in the data, which indicates optimum PDC selection should be based on available performance and geologic data.
Can Fluorohydrocarbon Elastomers Used in Oilfield Service Be Improved by Varying Carbon Black Type?
Authors: Cain D. E. , Peters L. A. , Pugh T. L. 
Published: December 2007

ABSTRACT
Elastomers for oilfield seals are often specified by hardness and generic type. Experienced compounders recognize that hardness of a seal can be achieved by many different formulations. The filler type and amount plus the cure system in these formulations have the most profound influence on the hardness. Carbon black and finely divided minerals are the most common fillers used in elastomer compounding.
This investigation evaluated the influence of the effect of carbon black particle size in fluorohydrocarbon formulations. Several fluorohydrocarbon compounds were formulated with carbon black types ranging from N330 to N990. These compounds were aged by exposure to aqueous hydrocarbon and gaseous fluids, which were intended to simulate oilfield environments. Changes in the physical properties of these compounds were determined and tabulated for comparison.

CONCLUSIONS
Improvement of BOP Sealing Systems Is an Urgent Requirement for HP-HT Deep Wild Well Control
Authors: Alliquander O. , Hingl J. , Szabo G. 
Published: December 2007

ABSTRACT
A recent high pressure and temperature wildcat well control operation of the Hungarian National Oil and Gas Co. on a 4 239 m/13,907 ft/deep well required 46 days up to capturing in closed cooperation with numerous major and service companies. The operating shaft damage of a BOP caused the blowout. Up-to-date technologies and materials, among others sophisticated elastomers were introduced because of the extremely severe conditions.
The wellhead temperature exceeded 130°C /300°F/, the flowing pressure varied between 36 and 48 MPa /from 3100 to 6900 psi/, and the produced fluids were aggressive-gas contaminated, superheated brine water, i.e. steam.
The sealing elements of the recommended BOP failed to work after 48 hours service, thus jeopardizing the specially designed snubbing operation.
On the basis of the case history, the conclusion of the paper calls for improvement of /1/ the wellhead equipment and blowout preventer systems, /2/ the achievement of harmony in the field of sealing elastomers and the employment of metal-to-metal seals and /3/ proper selection of elastomer formulations on the basis of environmental agents. The above three are the preconditions of successful wild well control operations.
Cementing High-Angle Wells Using Cement-Expanded Formation Packers and/or Casing Rotation
Authors: Webster M. B. , Otott G. E. , Rice D. L. 
Published: December 2007

ABSTRACT
This paper describes an ongoing program to improve primary cementing results for casing in high angle or deviated wells. Thums Long Beach Company, acting as Contractor for the City of Long Beach, Operator of the Long Beach Unit, has drilled and completed over 1100 wells from four man-made islands and four land filled pier locations. The average well exceeds 55° hole angle with some wells exceeding 80° from vertical.
Two techniques have been recently utilized to provide a competent shut-off between the completion interval and the surface. The first technique employs the installation of a twenty foot (20′) Cement Expanded Formation Packer usually set in a competent shale immediately above the completion interval. The CEFP is expanded with cement at the completion of the primary cement job. This method employing specifically approved equipment has proven so successful that the State of California will accept a successful installation as a substitute for the normally required water shut-off test.
The second technique involves the rotation of a selected length of casing at the bottom of the casing string. A specially designed casing swivel is integral to the casing string and is rotated by a spline drive installed on drill pipe. The casing segment is rotated during a conditioning period and while the cement is being placed. Up to 600′ of centralized casing has been rotated with excellent results in high angle wells.
Drilling Time Predictions from Statistical Analysis
Authors: Noerager J. A. , White J. P. , Floetra A. , Dawson R. 
Published: December 2007

ABSTRACT
Drilling, completion and trouble times have been collected for 489 platform wells and 51 subsea wells drilled in the North Sea. Equations have been fit to these data bases; these equations can be used to estimate times for wells to be drilled in the future.
Measured depth is the most important factor in predicting well times. Spud date and learning effects are also important. Hole angle has only a minor influence outside of its effect on measured depth.
The Application of Limited-Entry Techniques in Massive Hydraulic Fracturing Treatments
Authors: Cramer D. D. 
Published: December 2007

ABSTRACT
Application of the limited entry-technique has been extended to massive hydraulic fracturing (MHF) of low permeability formations, such as the Niobrara and Codell intervals of the DJ Basin.
Analysis of the bottomhole pressure data of these treatments indicates that proppant alters the mechanical configuration of the perforations, as evidenced by a change in the magnitude of perforation friction in opposition to the Bernoulli constant energy equation. The practical significance of changing pressure drop across perforations in limited entry stimulation treatments is that it alters treatment fluid distribution and injection rate profiles among the multiple intervals. This can result in zonal shut-off due to insufficient pressure drop (i.e., zone fracture pressure&gt; wellbore pressure) or zonal sand-out due to inadequate pad volumes and/or treating rate.
This paper investigates the mechanisms involved in fluid and slurry flow through perforations. Fluid mechanics research and experimental laboratory and field testing are referenced. The effect of proppant on perforation friction is calibrated. Limited entry design and procedural guidelines for large scale fracturing treatments are presented to assist in achieving the desired placement of fluid and proppant into individual zones. Fundamental limitations of the limited entry technique in MHF applications are also discussed.
The Effect of Excess Propped Fracture Height on Well Productivity
Authors: Cipolla C. L. , Lee S. J. 
Published: December 2007

ABSTRACT
A three-dimensional reservoir simulation study indicates that propped fracture height in excess of the productive thickness of the reservoir can add to well productivity. The effect of excess propped fracture height is more evident when fracture conductivity is relatively low compared to formation conductivity. The simulations indicated that in cases where dimensionless fracture conductivity (Cr), as defined by Cinco et al,1 is less than ten, any excess fracture height will increase well productivity. The magnitude of the productivity increase is a function of the dimensionless fracture conductivity and excess height.
A series of type curves is presented that compares the transient pressure behavior of hydraulically fractured wells where the propped fracture extends uniformly above and below the reservoir to the same wells where there is no excess fracture height. In addition, a comparison of the pseudo steady-state productivity increase that would be expected for a hydraulically fractured well is presented for wells with and without excess propped fracture height.
Selected cases are presented to illustrate the economic impact of excess propped fracture height and how it may affect proppant selection.
Modified Fracture Stimulation Techniques for Shallow Oil Sands in Carter County, Oklahoma
Authors: Marple G. T. , Ruley G. E. , Worley H. W. , Freeman E. R. 
Published: December 2007

ABSTRACT
Carter County in south central Oklahoma has 1000's of shallow oil wells producing from various formations less than 2000' in depth. These zones, although shallow, still require some stimulation to facilitate economic development. When a hydraulic fracturing procedure is dictated, the treatment typically utilizes lease crude or brine water as the carrying medium to transport a maximum sand concentration of 3 to 5 pounds per gallon. Preliminary studies have shown that by modifying this conventional fracture design, increases in well productivity may be achieved. These modifications include a more efficient carrying medium and an improved permeability contrast.
Ultra-High Conductivity Fracture Stimulations: A Case History
Authors: Barby B. G. , Barbee W. C. 
Published: December 2007

ABSTRACT
Ultra-high sand concentration fracturing is taken one step further by achieving tremendous fracture conductivity with extra large proppants. The results of these fracture stimulations demonstrate that the Morrow Formation can be impregnated with very large proppants in high concentrations to achieve production improvements.
Recent Advances in Fracture Evaluation
Authors: Noblett B. R. , Fertl W. H. , Guy J. O. 
Published: December 2007

ABSTRACT
Conventional acoustic logging devices have long been used for locating natural fracture systems which intersect the wellbore in a horizontal or near-horizontal plane. Such devices typically employ shear wave detection techniques applied to full-wave acoustic signatures. Loss of shear wave amplitude, coupled with increasing transit times in the presence of a fluid-filled fracture system, is used to determine fracture location. As the direction of fractures shifts toward the vertical plane with respect to the intersecting wellbore, conventional acoustic devices become unreliable for fracture detection purposes.
An acoustic logging system which uses circumferentially propagated waves can be used to identify and evaluate the presence of vertical and/or near-vertically oriented fractures in fluid-filled boreholes. When run with an orientation section, this new circumferential logging instrumentation is also capable of determining the major lateral direction of fracture systems and regional stress patterns.
Field examples and recently developed interpretive software developments are presented.
Study on the Effect of Pore Blocking Mechanisms on Formation Damage
Authors: Wojtanowicz A. K. , Krilov Z. , Langlinais J. P. 
Published: December 2007

ABSTRACT
The process of formation permeability damage due to solids movement and capture was quantitatively modeled by using principles of deep bed filtration and chemical reactions kinetics. The developed theory describes the pore blocking mechanism caused by particles from completion fluids (foreign particles invasion) as well as the mechanism of release and capture of rock fines (in-situ mobilization).
For practical applications, this theory was used in the context of pattern recognition, ie, to examine the experimental data on rock permeability change vs time from the laboratory flow experiments. Thus, a straight line section of data plotted in a certain system of coordinates indicates the type of formation damage occurring.
The verification study was performed in two series of laboratory experiments. In the first, a drilling mud, consisting of a contaminated completion fluid, was pumped through the simulated synthetic rock. In the second, four typical, solids-free completion brines were pumped through actual samples of water sensitive, unconsolidated sandstones taken from Adriatic Sea gas fields.
The experiments revealed the applicability of the theory and the method of diagnostic plots to describe and analyze formation permeability damage.
Surfactants Can Affect Corrosion Inhibition of Oil-Field Steel
Authors: Growcock F. B. 
Published: December 2007

ABSTRACT
Surfactants greatly improve the performance of t-cinnamaldehyde (TCA) as a corrosion inhibitor for J55 steel in hydrochloric acid. They function in this capacity by enhancing adsorption at the surface; increased solubility or dispersibility of the inhibitor is an incidental effect. The cationic surfactant n-dodecylpyridinium bromide (DDPB) is effective in this regard far below its critical micelle concentration, probably as a result of electrostatic adsorption of the monomeric form of DDPB; this leads to formation of a hydrophobic monolayer, which attracts the inhibitor. On the other hand, an ethoxylated nonylphenol (nonionic surfactant) acts by incorporating the inhibitor into micelles, which themselves adsorb on the steel surface and facilitate the adsorption of TCA.
Free World Total Primary Energy Demand: An Econometric Approach
Authors: Dougherty E. L. , Al-Blehed M. S. 
Published: December 2007

Abstract
This paper presents results of a modeling study undertaken to quantify the effects of recent changes in energy prices on future total energy consumption and oil's market share. To predict these two quantities vs time, five pairs of regional models, which together span the Free World, were developed. The explanatory variables in the models are income, population, total energy price, crude oil price, and non-oil energy price. The most recently published data were used to estimate coefficients in these models. Projections of total energy demand and oil share through 2000 for different scenarios are given. The sensitivity of future demand for crude oil to changes in income and prices is examined. Both multiple regression and linear programming were used to estimate coefficients. These two methods gave essentially identical results under identical conditions. Because the LP approach allows greater flexibility in imposing judgemental bounds on coefficients and selectively weighting historical data, it was used to obtain the coefficients presented.
We find that considerable judgement must be applied to obtain coefficients that cause the models to yield reasonable results. The tailored computer system developed to use the models allows hindcasting as well as forecasting. Hindcasting experiments reveal that a perfect history match does not always mean that the model will provide reasonable projections.
Exploration Strategy Development Under Volatile Pricing Conditions
Authors: Caldwell R. H. 
Published: December 2007

Abstract
This paper discusses techniques which may be used to evaluate the risk/reward relationship of exploration drilling under conditions of volatile pricing. The theme is developed through case studies where historical drilling statistics and discovered reserves are analyzed to develop probability functions which characterize each play. This information is further analyzed to develop ranking criteria as a function of oil price to characterize each play.
Thermal Model for Establishing Guidelines for Drilling in the Arctic in the Presence of Hydrates
Authors: Roadifer R. D. , Godbole S. P. , Kamath V. A. 
Published: December 2007

ABSTRACT
Natural gas hydrates exist in the North Slope of Alaska, the Northwest Territory of Canada, the U.S.S.R. and offshore waters deeper than 5,000 ft. Actual hydrate cores have been obtained from the Gulf of Mexico and the western coast of Guatemala. In addition, ARC0/EXX0N have recovered a gas hydrate core sample at a depth of 666 m in 1972 from N-W-Eileen Number 2 well in Prudhoe Bay, Alaska.
Drilling through hydrate deposits causes mud gassification and an increase in the drilling rate. Chilled drilling fluid with higher mud weight at high circulation rates are routinely used to avoid any possible problems due to severe gassification. This study involves a development of a thermal simulator to determine the position of the hydrate dissociation front and gas influx rate as a function of drilling conditions.
The solution of this problem involves the tracking of a moving boundary between thawed and unthawed hydrate regions. This is a r-z simulator for unsteady state heat conduction in the presence of a moving boundary. The heat losses to overburden as well as underburden are accounted for in the formulation of the model. A finite difference numerical scheme is used to generate temperature profiles in thawed and unthawed zones, and the hydrate dissociation rate during drilling.
Results are presented in graphical form for reservoirs with a range of porosity, geothermal gradients, mean annual surface temperatures, and pressures relevant for in-situ hydrate deposits in the arctic. Furthermore, these results provide quick guidelines for the selection of drilling variables, such as mud temperature, mud weight and circulation rate.
Pump-Off Control Application in Thermal Recovery Operations
Authors: Yoch R. J. , Williams R. L. , Jones J. A. 
Published: December 2007

ABSTRACT
Santa Fe Energy Company (SFEC) has planned to install pump-off controllers (POC's) on all new wells in the Midway-Sunset Field and is in the process of retrofitting the majority of its existing wells. This effort is the result of a year long, 88 well study begun in 1984 on pump-off control effectiveness on a predominately steam stimulated, Potter sand property. After a total capital investment of $345,000 ($4,100 per well), the 1985 gross revenue attributed to the POC installation was $472,500, and the trial achieved a ten month simple payout. This revenue does not include the one time cash rebate of $72,300 offered by the local utility for power consumption reduction. The revenue increase came from a 31% reduction in power consumption ($81,700 savings), a 23% reduction in well work expenditures ($66,800 savings), and a 47 BOPD increase in lease oil production ($343,100 revenue at $20/bbl oil, 1985 prices). The increase in production was due to reduced downtime, reduced problem frequency, and an accelerated recovery in the first month of post steam stimulation response. Details of the cost savings from the field study are provided in the discussion. A cursory evaluation of a 519 well expansion to three other Santa Fe properties will be conducted.
Observations and Recommendations in the Evaluation of Tests of Hydraulically Fractured Wells
Authors: Economides M. J. 
Published: December 2007

ABSTRACTThe pressure transient behavior of hydraulically fractured wells has been the subject of considerable study over the past few years. Several investigators have presented solutions of the fundamental equations, identified qualitative diagnostic trends and suggested interpretation techniques. This paper presents a systematic approach to the problem along with substantial observations on the potential of unique interpretations.Pre-treatment tests are considered here as necessary. Well tests in tight formations are often of very short duration, to allow the use of established methodologies. Hence, a technique to calculate the maximum reservoir permeability from a short well test is offered.In the case of post-treatment tests the data are treated using the convolution/deconvolution techniques and influence functions. The term "influence function" defines a relationship between pressure response and time at a constant unit surface flow rate. Although drawdown well tests have advantages over buildup tests because they are used while the well is producing, their interpretation has been hampered by varying flow rates. Conventional interpretation techniques assume either constant well flow rate or controlled variation of it. Pressure buildup tests are conducted with the well flow rate equal to zero and are, as a result, predominant.In the case of post-treatment well tests of hydraulic fractures a lengthy buildup test and the ensuing shut-in may result in severe damage to the generated fracture. Thus buildup tests are not always desirable for post-treatment evaluation. The convolution/deconvolution techniques and influence "functions," by normalizing the pressure response to a unit flow rate, permit the use of standard techniques for the analysis of drawdown tests.The interpretations presented here utilize new versions of pressure and pressure derivative type curves including the dimensionless fracture storage coefficient, and the dimensionless fracture conductivity. Based on observations of the sensitivity of the response to these parameters, three type curves have been developed, one for low, one for intermediate, and one for high conductivity fractures. The choice can be made on the basis of pre-treatment analysis and the fracture design. The storage and the half-length of the generated fracture can then be calculated with reasonable confidence.
Mechanical Interactions in Branched or Subparallel Hydraulic Fractures
Authors: Jeffrey R. G. , Vandamme L. , Roegiers J. -C. 
Published: December 2007

ABSTRACTA numerical simulator has been used in the study of a hydraulic fracture with two nearly parallel branches. The pressure required to propagate a branched fracture is found to be significantly higher than the pressure needed to extend a single planar fracture. Interactions with natural fractures have also been studied. The results show that hydraulic fractures may develop offsets at crosscutting natural fractures. Slip occurring on weakness planes after the hydraulic fracture crosses them has been modeled, demonstrating a reduction in fracture width at the site of the offset. This reduction in width may lead to proppant bridging at that location. An elastic calculation for the size of zones within which sliding may occur on preexisting weakness planes around a pressurized fracture indicates that the extent of these zones is proportional to the length of the pressurized fracture. Slip in such zones is controlled by the far-field stress, the pressure in the fracture, and the orientation and frictional properties of the weakness planes.