bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effects of Asymmetric Nozzle Sizing on the Performance of Roller Cone Bits
Authors: Wells M. R. , Pessier R. C. 
Published: December 2007

Abstract
A major factor governing the performance of roller cone drill bits is the efficiency with which the drilling fluid removes rock cuttings (and fines) generated beneath the bit. Traditionally, the hydraulics at the bit has been optimized by expressing the losses in the circulating system as a function of flow rate then maximizing either horsepower at the bit or impact force without regard to the position and size distribution of the nozzles.
This paper describes results obtained using a novel technique where the hydraulic cleaning and scouring of the bottom of borehole is optimized by using an Asymmetric Nozzle Sizing procedure. Unlike the conventional practice of uniform nozzle sizing, this procedure combines a single large nozzle with two smaller nozzles. The jetting action of the larger nozzle enhances the crossflow component of the global flow pattern and greatly intensifies the turbulence levels beneath the bit.
A series of laboratory experiments is discussed showing that turbulent fluctuating pressures measured along the hole bottom beneath a roller cone bit are significantly more intense and cover a larger area when using the asymmetric nozzle arrangement than when using conventional, uniform or equal size nozzles. In addition, the asymmetric nozzle configuration is shown to produce a substantial cross flow along the bottom of the borehole. The combination of intense turbulence and cross flow greatly enhance bottomhole scouring.
Finally, the results of a series of full scale laboratory drill tests are presented that quantify the advantage of asymmetric nozzle sizing and the need for increased hydraulic horsepower and bottom hole turbulence at greater depth. These results indicated an increase in the rate of penetration (ROP) on the order of 20% using the asymmetric nozzle sizing technique over that measured using conventional, uniform nozzle sizing. In addition, field tests results are provided that indicate similar or greater increases in ROP, longer bit life and greater savings (cost per foot) were achieved using asymmetric nozzle sizing.
The Role of Contingencies in Incentive Bid Preparation
Authors: Moy M. A. , Kent D. J. 
Published: December 2007

ABSTRACT
A different bidding strategy must be adopted by the Drilling Contractor when bidding for incentive contracts as opposed to normal dayrate contracts, if expected reward to be gained is to be equated to the additional risk taken during incentive operations. Risk analysis, in relation to expected or perceived drilling problems and which in turn are part of the Contractors contractual liabilities, is essential in all incentive type contracts. Based upon such an analysis the Drilling Contractor must then decide whether to accept the proposed contractual risk allocation, include contingencies in the price, make contractual exceptions, take out insurance to cover the risk assumed, or adopt any combination of the aforementioned solutions. This paper addresses risk analysis in relation to the risk-reward scenario, and suggests a methodology /procedure for assessing and calculating the risk when preparing incentive bid proposals.
Superior Performance With Minimal Environmental Impact: A Novel Nonaqueous Drilling Fluid
Authors: Friedheim J. E. , Pantermuehl R. M. 
Published: December 2007

ABSTRACT
The first well utilizing a novel drilling fluid based on polyalphaolefin (PAO) chemistry has been drilled in the North Sea. In addition to excellent drilling performance, PAO drilling fluids exhibit low toxicity, low bioaccumulation, and are biodegradable. Success of the PAO mud has established the system as a viable synthetic-based alternative to oil-based muds.
The non-aqueous PAO system was used to drill the 12.25-in. section of a well in the Central Basin of the North Sea. The interval from 6,300 to 15,067 ft (1,920 m to 4,592 m) was drilled at an angle of 55 deg. The formation consisted primarily of tertiary shales mixed with limestone stringers. Mud weight range was 15.0-15.5 ppg (1.8-1.86 s.g.).
Comparisons with oil-based muds used in this area of the North Sea indicated the PAO fluid helped increase penetration rates and reduce torque and drag. Other performance benefits included superior hole cleaning and no evidence of weight material sag. Additionally, cuttings discharged into the sea retained an average of less than 10% PAO (&lt;100 g/kg dry retort solids).
Comparisons with other non-aqueous alternatives such as ester and ether-based fluids show PAO systems provide better elastomer compatibility, lime and cement tolerance, surface handling, synthetic/water ratio flexibility, and temperature stability.
This paper covers drilling and fluid performance results of the first field trial of a PAO-based mud. Environmental data including toxicity, bioaccumulation, and cuttings beds studies also are discussed. Chemical and practical differences between PAO and other synthetic-based muds are presented.
Fracture Mechanics Issues Relating to Cuttings Re-Injection at Shallow Depth
Authors: Willson S. M. , Rylance Martyn , Last N. C. 
Published: December 2007

ABSTRACT
Re-injection of oil contaminated drill cuttings is attracting considerable attention as a cost effective means of complying with environmental legislation concerning discharges of drilling wastes. Gyda is the first North Sea platform to adopt this method as the sole means of disposing of its drilling wastes. The ground cuttings slurry (ca. 15,000 bbls per well) is injected via the 13 3/8" × 9 5/8" casing annulus into hydraulic fractures of up to 213m radius created in the mudstone formation at 900m depth.
Novel analyses using a 3D fracture simulator show that in the absence of stress or permeability barriers to prevent unconstrained height growth, fracture breakthrough to surface is theoretically possible if injected volumes exceed 90,000 bbls. The analyses further demonstrate that laterally extensive shallow sands do however provide effective permeability barriers to vertical height growth if injected volumes exceed 52,000 bbls.
An Improved Method for Grinding and Reinjecting of Drill Cuttings
Authors: Sirevåg Gunnar , Bale Arthur 
Published: December 2007

ABSTRACT
A successful reinjection of oil-wet drill cuttings has been performed on the Norwegian Gullfaks Field. The reinjection was carried out in the annulus between two casing strings through a wear-protected wellhead. An effective way of grinding cuttings and mixing slurry by use of a new patent pending method known as SMACCC – Statoil Method for Autogenous Crushing and Classifying of Cuttings has been developed.
The paper discusses reservoir aspects and presents simulated fracture geometries as a result of rock mechanical and slurry in-put property data. Further, the paper describes a 1000 hour wear test, involved equipment, and gives a derived formula describing wear from sand slurries on internal wellhead components.
Present Methods of Drilling Process Analysis, Forecasting, and Control in Conditions of Insufficient Information
Authors: Mnatsakanov A. V. , Shirin-Zade S. A. S. 
Published: December 2007

Abstract
In many cases the technological processes of drilling wells, especially in exploratory drilling, are carrud out in conditions of insufficient information.
Shortage of information is connected with lack of data on geological features of the drilled area, rock physical, mechanical and rheological properties, with complexity and uncertainly of heat-mass exchange processes in the system "well-formation", drill pipes and casing interaction with rocks, bit interaction with boffom hole and so on. Besides, it should be noted, that the driller often deals with misrepresented initial information. It is in these conditions it is nessesary to investigate multicriterion complicated technological process of drilling and provide high effeciency of decisions made in conflict situations. Howether, the experience and intuition do not always provide the best choice in these conditions. The objective can be accomplished only on the base of complex approach to the procedure of making decisions and using the up-to-day methods of investigation of complicated and undefined systems.
In the paper, depending on the significance and complexity of the investigated technological process, different methods of making decisions in the conditions of insufficient information are considered.
For this, the principles of simulation, methods of indistinct sets, variation principles of mechanics, present achievements of dynamic systems theory are used.
An Analysis Accounting for the Combined Effect of Drillstring Rotation and Eccentricity on Pressure Losses in Slimhole Drilling
Authors: Cartalos Ulysse , Dupuis Dominique 
Published: December 2007

Abstract
Knowledge of the distribution of pressure losses is a key factor to the design of a slimhole well. However, predicting annular pressure losses-the major partis difficult because drillstring motion makes nonnegligible complex contributions that have not been accounted for up to now.
Flow in an eccentric annulus with eccentricity varying in the axial direction is studied. The effect of rotation induced transverse vibrations is included by allowing time periodic variations of eccentricity. The resulting model predictions can reproduce trends observed in field data.
A New Tool Joint Design Increases the Fatigue Life of Drillpipe Tubes
Authors: Wilson G.E. 
Published: December 2007

SPE and IADC Member

Abstract
Premature failures in drill pipe have plagued the drilling industry for a long time. These failures usually occur within two feet of the box and pin tool joints. Previous work has shown that most of these failures are the result of an abrupt internal taper (1/2" - 1-1/2" long) (12.7 - 38.1mm) and slip damage. New long taper upset designs have helped solve this fatigue problem. This paper discusses a new stress relief tool joint that greatly enhances the benefits of the new, long taper upset by almost doubling the fatigue life.

Introduction
Fatigue failures in drill pipe are caused by cyclic bending stresses. These stresses are concentrated in the thin wall section of the drill pipe where the thick upset blends into the tube. I believe drill pipe today is being subjected to higher and higher stresses with the advent of top drives, deeper wells and higher angle holes. This condition is further agitated by a more hostile environment with the increasing presence of H2S, CO2 and brine water. Therefore, I believe everything possible should be done to improve the fatigue life of drill pipe. Both the long taper upset and the new stress relief tool joint will help accomplish this.

REVIEW OF PROBLEMS AND PREVIOUS TEST WORK
I think the problem of drill pipe fatigue has been sufficiently defined. Many drilling contractors and oil operators along with the IADC and API have made studies of a vast number of failures, and most all of them pointed to an abrupt upset along with slip damage as being the problem. It has also been observed that rapid deterioration of the internal, plastic coating in this area compounds the problem.
P. 893^
Surface Measurement and Analysis of Drillstring Vibrations While Drilling
Authors: Macpherson J. D. , Mason J. S. , Kingman J. E. E. 
Published: December 2007

Abstract
Drillstring vibrations while drilling cause premature drillstring component and bit failure, and represent a waste of drilling energy. To increase drilling efficiency, drillstring vibrations are monitored and analyzed and the optimum drilling parameters and practices are determined as a well is drilled. This results in a reduction in the frequency of drillstring failures and the amount of time spent tipping and/or fishing, and an increase in both bit life and drilling rate.
This paper presents vibration signatures and analyses selected from over 15,000 hours of vibration data obtained using a surface vibration measurement sub. The case histories demonstrate the surface detection of drillstring resonance, BHA (Bottom Hole Assembly) lateral vibrations, PDC (fixed cutter) bit whirl, shock sub closure, torsional string oscillations, premature bit bearing failure and impending stuck pipe.
The Effect of Micro-Fractures on Oil Recovery From Low-Permeability Reservoirs
Authors: Perez J. M. , Poston S. W. , Edwards C. M. 
Published: December 2007

Abstract
The application of horizontal drilling has made exploitation of oil from low matrix permeability, naturally fractured reservoirs feasible. However, enhancing recovery from this reservoir type presents a distinctive problem. The low porosity and permeability matrix is virtually unaffected by the fluids injected into the extremely high permeability fractures. These fractures are multi-leveled and range from large scale macro-to small scale micro-fractures.
The effects that the presence of fractures on oil recovery due to water imbibition was studied. Both unadulterated and carbonated water imbibition tests were conducted on Indiana Limestone cores confined by a fluid pressure of 800 psi. Water was enriched with CO2 at a 500 psi carbonation pressure for the carbonated water cases. Magnetic Resonance Imaging (MRI) methods were used to study the effects that micro-fractures have on their surrounding rock matrix during oil production by water imbibition.
The presence of micro-fractures revealed that several factors may assist oil displacement: Capillary forces drive water into the microfracturesIncrease in the surface area available for water imbibitionOil trapped in fractures can be displaced by this process.An adequate wettability facilitates the process
Inclusion of CO2 improved oil recovery by: Increasing the oil mobilityA solution gas drive induced by the evolving CO2 when the system pressure is decreased below the carbonation pressure.
The presence of micro-fractures wide enough to allow appreciable fluid movement, increased oil production when compared to production from homogeneous rock. Imaging studies showed water channels were formed within the fracture system.
The presence of micro-fractures used the beneficial effects of capillary forces within the fracture system to create fluid paths that assist oil production. CO2 dissolved into the water being imbibed by the rock was found to accelerate oil recovery rates and increase ultimate oil recovery when compared to unadulterated water imbibition.
A New Simplified Compositional Simulator
Authors: Buchwalter J. L. , Miller C. A. 
Published: December 2007

Abstract
A new simplified fully implicit compositional simulator has been developed. This simulator is different from existing models because it combines the conventional black oil equations with a compositional injection component equation. The simulator runs at speeds that far exceed the speeds in current compositional simulators, primarily because the speed is independent of the number of components. Data preparation is both simplified and improved because component pseudoization is not needed. The simulator has been tested successfully for gas cycling projects including the Third SPE Comparative Solution Project and CO2 flooding projects.
Optimization and Evaluation of Openhole Cavity Completion Techniques for Coal Gas Wells
Authors: Logan T. L. , Mavor M. J. , Khodaverdian Mohamad 
Published: December 2007

Abstract
An innovative completion technique that has been used to effectively complete coal gas wells is an open-hole completion in which the coal is encouraged to slough into the wellbore. During the completion process, the wellbore is effectively linked to the reservoir due to the creation of numerous multi-directional self-propped fractures. The technique has been commonly called an "open-hole cavity completion." However, the cavity is a by-product of the process and not the primary objective of the completion. A more suitable terminology for the technique is "dynamic open-hole completion." The majority of the dynamic open-hole completions have been performed in the Fruitland Formation of the San Juan Basin, Colorado and New Mexico. Dynamic open-hole completed coal gas wells in some areas, but not all, produce at significantly greater rates than wells completed using other techniques such as hydraulic fracturing. Because of the success in the San Juan Basin, dynamic open-hole completions have been attempted in other basins including the Piceance, Powder River, Arkoma, Uinta, and Black Warrior. This paper presents a conceptual model and a working hypothesis concerning what takes place in the coal reservoir during the dynamic open-hole completion process. Based upon this model and hypothesis, techniques to: i) optimize the completion, ii) evaluate the effectiveness of the technique, and iii) how to determine when to terminate completion operations will be presented.
Drilling Successfully through Deforming Shale Formations: Case Histories
Authors: Talabani Soran , Chukwu Godwin , Hatzignatiou Dimitrios 
Published: December 2007

Abstract
Shale sloughing and swelling are the two major problems encountered when drilling through shale formations. Some areas are characterized by shale sections containing bentonite or other hydratable clays, which continually absorb water, swell and slough into the hole. These types of formations are known as heaving shales. This problem, if left uncombated, results in high cost of drilling the hole and significantly, to other hole problems (pipe sticking, excessive solid buildup in the mud and hole bridging), and sometimes abandoning the well because of the difficulty of reaching the targeted or anticipated pay depth. Drilling through shale formations can, many a time result to hole stability problems and may be aggravated the more when drilling through more than one kind of shale lithology.
The existing literature addresses possible solution techniques to combat the shale problems based on laboratory studies but these techniques neglect the existence of shale heterogeneities which may cause sloughing and swelling while drilling the same shale formation.
This paper examines the physical appearance of various shale samples with a view to (a) determining the physical properties which contribute to the shales' undesirable properties, and (b) proposing methods to minimize their effects on drilling performance. Five field cases are presented where sloughing and swelling shales were encountered. These cases reveal that the heterogeneity of the shale formations can cause difficulties in controlling the sloughing and/or swelling problems because of the variations in shale composition, ion exchange capacity, formation water content and shale strength.
Case History of Pressure Transient Testing at McElmo Creek, Utah
Authors: Shaw E. C. 
Published: December 2007

Abstract
This paper presents the results of a review of over eight hundred historical pressure tests conducted in the McElmo Creek Unit of southeast Utah. Three hundred pressure transient analyses were performed. The paper describes how this data base was used to characterize trends in pressure, reservoir quality and stimulation effectiveness. The various techniques used to acquire the pressure data are also discussed.
Special Aspects of Applying Constant Rate Analysis Approach in Low-Permeability Formations
Authors: Enachescu Cristian , Ostrowski L. P. 
Published: December 2007

ABSTRACT
This paper describes special aspects and problems encountered when analysing transient pressure tests in low permeability formations. A constant rate approach has been widely used in oil and gas industry for analysing well tests. However, in low permeability formations special problems arise in applying the constant rate analysis method.
First, using the constant rate approach the pretest borehole history must be approximated. As it acts as a long term constant pressure injection or production event while drilling through the test interval it results in the creation of a non-uniform pressure distribution in the vicinity of the borehole. Numerous field examples show that after the packer system is set a distinct pressure build-up or fall-off occurs. The non-uniform pretest pressure distribution cannot be neglected in the analysis of the subsequent test events e.g. DST sequence. Significant errors may occur in estimation of the reservoir parameters, in particular the initial pressure.
Second, the use of the constant rate approach in analysing the DST sequence in low permeability formations leads to errors unless the rate sequence, and thus superposition function, is constructed properly. A new method of rate discretisation for the initial discontinuous events (the beginning of the 1st. and 2nd. DST flow period) is presented and the errors resulting from neglecting the true rate sequence are discussed. Field examples present the application of both concepts.
The main objective of this paper is to show that by simple measures it is possible to take account of borehole history and apply rate discretisation to improve the accuracy of interpretation when using standard constant rate analysis software.
Nuclear Tracer Saturation Imaging of Fluid Displacement in Low-Permeability Chalk
Authors: Graue Arne 
Published: December 2007

ABSTRACT
A nuclear tracer imaging technique is evaluated for use in core analysis in studies of oil recovery from chalk reservoirs. In-situ fluid saturation data in long-core flood experiments in chalk, enhance the interpretations of the data; especially in mapping the local recovery efficiencies. In various long core flood displacements, including both drainages and waterfloods, emphasis has been on recording local in-situ saturation development, obtaining recovery efficiencies and studying effects on the saturation profiles from displacement pressure drops, flow rates and initial and final water saturations. The benefits of having access to local in-situ saturation information, the importance of being able to identify rock heterogeneities and tests of repeatability have been stressed.