bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating Fracture Height from Gamma Ray Spectroscopy of Radioactive Tracers: A Case Study
Authors: Willis G. B. 
Published: December 2007

ABSTRACT
Five wells in the Big Horn Basin of Wyoming were perforated in the Phosphoria formation and subsequently treated with acid. Each of the acids was tagged with a radioactive isotope. Spectral gamma ray logs were then run to determine the effectiveness of the treatments. After processing and analyzing the data, two facts became evident: 1) Several pitfalls need to be avoided in selecting the isotope and designing how the acid is tagged. For example, the correct isotope must be selected with the correct specific gravity to allow the isotope to stay suspended in the treatment fluid and the borehole fluid must be displaced with non-radioactive fluid. 2) Looking at total gamma ray counts alone to determine isotope distribution is inconclusive and sometimes misleading because this does not distinguish between tracer material in the borehole from tracer material in the formation.
When gamma rays pass through any median such as formation, cement, and casing, Compton downscattering occurs.(1) By applying a weighted least squares (WLS) algorithm to the gamma spectroscopy data, the compton downscattering was taken into account to determine both borehole and formation components.
The geology of the formation, treatment design, isotope design and isotope selection are discussed as they apply to the log data. The logging procedure, processing of the log data, and log examples are presented in more detail as this is the main thrust of this paper.
Fracture Patterns in Low-Permeability-Sandstone Gas Reservoir Rocks in the Rocky Mountain Region
Authors: Laubach S. E. 
Published: December 2007

ABSTRACT
Fracture permeability is of primary importance to producibility of gas from many low-permeability-sandstone gas reservoirs in the western United States, but the location, orientation, spacing, and connectedness of fractures in the subsurface is difficult to measure directly. The Upper Cretaceous Pictured Cliffs Sandstone (San Juan Basin, Colorado and New Mexico) and Frontier Formation (Green River Basin, Wyoming) form low-permeability gas reservoirs for which production data indicate locally important fracture permeability. In the wells studied, fractures are present in core or visible on borehole-imaging logs. Insight into the types of fracture patterns that may occur in these rocks could help guide exploration, completion, and stimulation strategies.
Maps of fractures provide the most accurate representation of fracture spatial distribution, trace length, connectivity, and size and shape of fracture-bounded blocks. In mis study, fracture patterns were characterized by mapping large exposures of Pictured Cliffs and Frontier sandstone along the margins of the San Juan and Green River Basins. A set of fractures is recognized in both formations that is interpreted as having formed in flat-lying rocks prior to local Tertiary folding and uplift. In contrast to the conventional map pattern of regional fractures, in which fractures are arranged in regularly spaced, orthogonal arrays, these fractures occur in discrete swarms separated laterally by domains that either lack fractures or that have only rare fractures. These less fractured domains may be as much as several hundreds of meters wide. Within swarms, fractures are well interconnected along the length of the swarm, but poorly interconnected across the width of the swarm. Fractures between swarms are commonly isolated. For the Pictured Cliffs and Frontier outcrops that were studied, the fracture pattern is self-similar over scales ranging from outcrop to interwell scale with fractal dimension D = 1.2. In the low-permeability sandstones of the Rocky Mountain region, irregularly spaced fracture swarms are potential targets for gas exploration and should be incorporated into fractured-reservoir models.
An Improved Gelled Oil System for High-Temperature Fracturing Applications
Authors: Cramer D. D. , Dawson J. , Ouabdesselam M. 
Published: December 2007

ABSTRACT
A gelled oil system has been developed for high temperature fracturing treatments. It uses several innovations, including two-stage gelation and a liquid gel breaker. The system works by adhering to rigorous testing and quality control procedures. Case histories in the Williston and D-J Basins document the results obtained with this improved system.
The Effects of Viscoelasticity on Friction Pressure of Fracturing Fluids
Authors: Keck R. G. 
Published: December 2007

ABSTRACT
Despite the existence of many correlations to predict the friction pressures of fracturing fluids, there is little understanding of the effects of viscoelastic properties on this behavior. One reason for the relative lack of understanding of this problem is that the interactions between the turbulent velocity fluctuations and the viscoelastic fluid properties that cause the observed friction pressures are extremely complex. As a result, there are no theoretically-based methods for either pipe diameter scale-up or friction pressure predictions for fracturing fluids.
This paper presents an attempt to predict turbulent friction pressures of fracturing fluids by extending results of a numerical simulation for viscoelastic fluids found in the literature. The literature work provides near-wall velocity profiles for two viscoelastic fluid models. These profiles are integrated to generate friction factor versus Reynolds number expressions with the Deborah number as a parameter. Comparison to available data shows good agreement but requires an independent calculation for the Deborah number. Calculations using three Deborah number correlations yield inconsistent results. The lack of agreement between the theory and the data suggests increased modeling sophistication is needed to predict friction pressures of fracturing fluids in turbulent pipe flow.
Slant-Hole Completion Test in the Piceance Basin, Colorado
Authors: Myal F. R. , Frohne K-H. 
Published: December 2007

ABSTRACT
The Piceance Basin of western Colorado contains a major gas resource in the tight naturally fractured sandstones, siltstones and coals in the Mesaverde. The objective of the Slant Hole Completion Test, funded by the U.S. Department of Energy, is to evaluate directional and horizontal drilling as an alternate development strategy for these reservoirs.
The well is located 700 ft south of the DOE Multiwell Experiment site in Section 34, T6S, R94W, Garfield County, Colorado. The hole was designed to intersect the paludal Mesaverde at 60° beneath the Multiwell pad and continue north to intersect the Cozzette close to 90°. The well is positioned to drill normal to the regional fracture system. Coring operations included a coal pressure core, 276 ft of conventional core across two paludal sandstones, and 118 ft of conventional core perpendicular to the natural fracture system in the Cozzette.
Drilling operations proceeded as planned through the first build interval, pressure coring, and conventional coring in the 60° hole. Subsequent caving in the coal and in the adjacent naturally fractured siltstone, in conjunction with lost circulation in the Rollins, necessitated prematurely running 7-in. casing below the Rollins. The remaining 800 ft of hole drilled was 6-in. diameter, cased with 4-1/2-in. liner. The high hole angle, in conjunction with the long tangent (60°) section (1,824 ft), made sliding the 4-3/4-in. motors in the second build extremely difficult. Drillpipe conveyed logging operations were successfully conducted in the Cozzette.
Productivity of Horizontal Wells
Authors: Al-Haddad S. M. , Crafton J. W. 
Published: December 2007

ABSTRACT
Many horizontal wells are being drilled all over the world. One of the objectives is to increase the well productivity, compared to vertical wells. This increase in productivity occurs in a naturally fractured reservoir because many fissures are intercepted by the horizontal well. A two phase (oil and water), two dimensional simulation model, that uses the single porosity formulation and divides the reservoir into blocks that contain either matrix or fracture, has been solved implicitly to simulate naturally fractured reservoirs. This simulator is able to represent the transverse imbibition observed in a laboratory experiment. The impact of horizontal and vertical wells on the produced water oil ratio and the cumulative oil recovery, has been studied for fractured reservoirs with different matrix permeabilities. The horizontal well, in general, gives a lower water oil ratio and a higher cumulative oil recovery. It was also found that the horizontal well productivity is better in low matrix permeability, fractured reservoirs.
Extension of Fracture Pressure Decline Curve Analysis to Fissured Formations
Authors: Mukherjee H. , Larkin S. , Kordziel W. 
Published: December 2007

ABSTRACT
Currently, a major part of our oil and natural gas production comes from wells in tight naturally fractured or fissured formations. In many cases, the commercial viability of these wells depends on the success of hydraulic fracturing. Properly designed fracture treatment enhances the production from these wells substantially. However, the complexities of fracture treatment of such reservoirs often lead to premature screenouts due to accelerated leakoff in the fissures from stress sensitivity. Normally, the fissures dilate with increased treatment pressure and the permeability of these fissures increases exponentially as suggested by Walsh1 model for stress sensitive fissures. Such stress or pressure sensitivity of fissures need to be diagnosed and remedied before a successful optimum treatment can be achieved in these formations.
Conventional minifrac analysis of injection pressure and decline pressure often helps in diagnosis of such pressure dependent leakoff case. The original Nolte decline analysis was for wall building fluids or for a constant leakoff case. When this analysis is applied to the pressure dependent leakoff case, the fluid efficiency is over-predicted suggesting inadequate pad volume and pump rate requirements. Such designs with inadequate pad volumes often cause proppant dehydration and premature screenout.
This paper presents a modification to Nolte's decline curve analysis that helps in the diagnosis and evaluation of pressure dependent leakoff. It is also observed that such analysis leads to substantially lower fluid efficiency calculation resulting in increased pad volume and treatment rate. By applying the suggested method of analysis an empirical relation between the net pressure and fluid leakoff coefficient can be obtained.
Fracturing Fluid Loss at High ∆P: Laboratory Tests and Field Applications
Authors: McMechan Dave E. 
Published: December 2007

ABSTRACT
An increasing number of gas wells that exhibit a large difference in reservoir pressure and fracture treating pressure recently have become candidates for hydraulic fracturing. When these reservoir conditions are encountered, the result is an abnormally high pressure differential driving the fluid leakoff mechanism during the hydraulic fracturing treatment. In some deep well applications, fluid loss differential pressures (FLDP) up to 10,000 psi have been witnessed.
Neither laboratory core testing nor conventional minifrac techniques have accurately predicted fluid loss behavior for fracturing treatments in these wells. Standard laboratory test procedures use differential pressures of 1,000 psi (as per API recommended test procedures) to determine fluid loss coefficients. Minifrac test methods and analysis techniques currently used for field application estimates of fluid loss parameters were modeled after data measured in gas reservoirs where normal fluid loss differential pressures occur.
Laboratory fluid loss testing typically has predicted significantly less fluid loss than actually is encountered. Use of this data in computerized fracturing simulators to design the treatment has resulted in many premature screenouts. Conversely, minifrac tests tend to be pessimistic and overpredict the fluid loss in wells with very high FLDP's. A number of treatments have been completed successfully following minifrac tests that predicted screenouts for the jobs actually pumped.
This paper reports on laboratory fluid loss tests conducted at differential pressures of up to 9,000 psi to determine the nature of the fluid loss occurring in these wells. Significant spurt volumes have been observed even on cores of less than 1 md permeability with fluid systems that do not exhibit measurable spurt loss at the conventional 1,000 psi test pressure differential. Also, the fluid loss coefficients (Cw values) have varied little with escalating pressure differential, contrary to many published correlations.1 Results from actual field cases also are reviewed as illustrations where the observed FLDP was several thousand psi during fracturing.
New Concepts for Vertical Drilling of Boreholes
Authors: Oppelt J. , Chur C. , Feld D. , Juergens R. 
Published: December 2007

ABSTRACT
Directional drilling equipment has been developing from conventional whipstock rotary assemblies over downhole motors with bent housing to navigational motors. A self-contained downhole automatic closed loop system is recognized as being the next major development milestone. As a first step such a drilling tool which automatically compensates for any deviation from the vertical direction has been introduced within the German scientific super-deep drilling project KTB. Technical function of the tool as well as recent field experience is reported.
Pore Pressure Ahead of the Bit
Authors: Hanson J. M. , Tibbitts G. A. 
Published: December 2007

ABSTRACT
This paper discusses the results of a numerical study of the effects of wellbore overpressure on the effective stress encountered by a PDC cutter. Results suggest that the length of time for the creation of the work face damage zone may strongly influence the effective rock strength felt by the bit in low strength formations. Field observations of large ( &gt; 0.5 in.) cutter bit performance in weak formations can be explained by these model results.
Hydrodynamics of the Drilling in Deep, Thick, Abnormal Pressure Reservoirs
Authors: Mnatsakanov A. V. , Litvinov A. I. , Zadvornykh V. N. 
Published: December 2007

ABSTRACT
This paper reports a general hydrodynamics theory of steady-state isothermal flow of non-linear viscoplastic drilling muds through the annular space of the well. The theory has been developed to fit an optimal circulation program design for conditions of high probability of circulation losses and/or formation fluid kickings. Mud compressibility problems are discussed as well as the adequacy of different rheological models to the behaviour of various mud types.
There are briefly stated fundamentals of the engineering procedure used to design optimized rheohydraulics programs for drilling wells. The said procedure with the corresponding computer program has been successfully used for drilling in deep thick abnormal pressure reservoirs of several Soviet oil and gas fields (Tengiz and others).
Helicopter-Supported Drilling Operation in Papua New Guinea
Authors: Wagner E. R. , Juneau M. S. 
Published: December 2007

ABSTRACT
Drilling cost per foot of Chevron's helilift drilling operation in the remote Southern Highlands of Papua New Guinea was reduced from 1360 to 267 $/ft (4462 to 876$/m) during the period from 1985 to 1989. The operation provides many challenges, as it is thousands of miles from major oil-field supply centers. This requires advanced well-planning and logistical management of drilling materials so that they arrive at the drilling rig in a timely matter. The wells are also drilled into structurally complex geology without the aid of seismic data which can lead to unexpected results. The drilling rigs are entirely supported by helicopters from a forward supply base and are completely heli-transportable. PNG's operational improvement and optimization program during a 5 year period had a four-fold decrease in drilling dollars per foot.
Development and Field Trial of a Biodegradable Invert Emulsion Fluid
Authors: Peresich R. L. , Burrell B. R. , Prentice G. M. 
Published: December 2007

Abstract
This paper presents the development and field trial of a novel biodegradable invert emulsion drilling fluid.
Responding to environmental concerns and legislation restricting the discharge of mineral oil base drilling fluids, research into biodegradable alternatives commenced in the mid 1980's. Laboratory testing found that some complex esters form stable invert emulsion fluids and are readily biodegradable in both aerobic and anaerobic environments.
After reviewing the laboratory and environmental data, the Norwegian Government agencies (SFT and NPD) granted their approval for a limited field trial of the new ester mud system. The Ester mud system was successfully used in an Ula Field appraisal well. Hole conditions and drilling rates were comparable to nearby wells drilled with conventional Oil Based Mud. Compared to an offset well drilled with a water base mud, normalised drilling time savings of 13.2 days were realised over two hole sections.
Toxicity levels on new and used mud samples have been well within Norwegian government statutorylimits for drilling muds. An independent laboratory biodegradation test on used field mud found it81% degraded after 28 days, allowing the ester mud to be classed as "readily biodegradable" by European Community (EC) protocol.
To assess the environmental impact, a long-term seabed survey programme at the wellsite is ongoing.
Chemistry and Field Practice of High-Temperature Drilling Fluids in Hungary
Authors: Dormán J. 
Published: December 2007

ABSTRACT
The development of new high-temperature drilling fluid formulations and field practice optimization is a major task worldwide. The role of divalent ions in colloidal stabilization led to the field proven Ca-muds especially under high-temperature conditions. In case of gyp-muds however Ca-tolerant dispersants, protective colloids and specialty chemicals must be used. Sulfomethylated (chemically crosslinked) lignite derivatives have been developed and used extensively for rheology and filtration control in deep and hot wells in Hungary. Optimized combination of modified lignites and selected low and high molecular weight synthetic polymers gave further improvement in temperature stability of high weight Ca-muds. Field results in several wells proved the performance of new synergistic blends at temperatures up to 490-500 K (225 °C).
Field and lab data showed the very special role of chemical equilibrium.
On theoretical basis and experience gained recently new lime mud formulation was developed. The relatively high filtrate Ca++ - inspite of high pH - combined with K-ions provides exceptional inhibitive properties.
The very special combination of synthetic polymers gives extreme temperature stability and unique performance.
Ionic and polymeric colloidal stabilization opens nwe ways in high-temperature drilling fluid formulations.
These systems have been successfully used in HPHT wells and show new promises in geothermal drilling as well.
Noise Reduction and Improved Hearing Protection on MODUS
Authors: Smith G. D. , Gloeckler D. 
Published: December 2007

ABSTRACT
This paper will report on a program which has been initiated to improve working conditions on MODUS(Mobile Offshore Drilling Units) through reduction of noise level exposures for all personnel. Theprogram contains four (4) approaches to the problems of air and structure borne noise on MODUS and will review the modifications that have been implemented or will be completed to provide lower levels ofexposure through hardware or systems changes as well as improved personal protection.
Improved Heave Compensation
Authors: Baker R. J. 
Published: December 2007

Abstract
The efficiency of drilling operations carried out from floating drilling units in hostile environments is adversely affected by movement of the vessel, particularly heave. Over the years various systems have been developed in an endeavour to minimise the problems caused. This paper describes the impact that heave has on the efficiency of floating drilling operations, the compensatory methods and systems that have been used to date, and highlights some new developments that promise to improve safety and drilling performance, while reducing the potential adverse environmental effects of drilling operations.
Downhole Blowout Preventer
Authors: Sangesland S. , Sivertsen A. , Hiorth E. 
Published: December 2007

ABSTRACT
A Down Hole Blow Out Preventer (DHBOP) for the downhole control of gas kick has been developed. Tests performed on an onshore drilling rig with simulated gas kick have demonstrated that the tool can effectively seal off the borehole, while mud of adequate density (to control the borehole pressure) is circulated above the Down Hole Blow Out Preventer.
Removal of a Kick With the Partition Method
Authors: Fleckenstein W. W. , Mitchell B. J. 
Published: December 2007

ABSTRACT
This paper compares kick removal variables between the "Partition Method", the Driller's Method, and the Wait and Weight Method. In the Partition Method, the kick is circulated out of the wellbore in discrete partitions which yield lower pressures within the wellbore, casing and surface equipment than the two conventional methods.
A Study of Load-Shape Factors of Jackup Legs With Raw Water Guides
Authors: Jensen A. G. , Orbe F. G. 
Published: December 2007

ABSTRACT
Shape factors for five different configurations of a triangular jack-up leg have been determined through load measurements on scale models in a wind tunnel.
The drag, lift, and yaw-moment shape factors of the different configurations were determined in the search for an optimal arrangementof the three raw water pipes that minimize the current load on the combined jack-up leg-raw water pipe-structure.
Horizontal Drilling in a Depleted Sour Gas Reservoir: A New Application
Authors: Niggemann L. , Ehlers R. 
Published: December 2007

Abstract
A horizontal well has been drilled in the depleted Siedenburg sour gas field with an H2S content of 6.7%. Concession holders of this field, located in N-W Germany, are BEB and Mobil.
The field has been producing since its discovery in 1964, from 2 reservoirs, the Middle Bunter sandstone and the Main Dolomite, both now depleted to a pore pressure gradient of 0.5 and 0.3 bar/10 m respectively.
A horizontal well in the Main Dolomite, if feasible, was considered as the best solution to increase recovery from the reservoir, by reducing the water influx and creating greater access to the reservoir by increasing millidarcy-feet.
After the reservoir engineering aspects of this project indicated a potential 5-8 fold production increase with a 400 m long horizontal completion interval, the drilling and completion aspects were analyzed for technical feasibility.
Restrictions in surface location and target description (2 intermediate targets) required build rates of appr. 4°/30 m in the 8-3/8" hole section and a medium radius profile of about 13.5°/30 m in the 5- 7/8" section. Both drilling phases had to be accomplished in geologically difficult formations with tight target tolerances.
The proposed entry point was planned to be as close as possible to the old Z-2 well in an area of the reservoir where best facies was expected. The walk tendency experienced in the offset well Z-2 was used for planning the final profile and therefore no directional work was required in the top hole section to line up the well for the final target direction.
Finally it was required to drill horizontally with a hydrostatic overbalance as high as 240 bar to maintain safe operating conditions in a severe H2S environment. The hydrostatic overbalance of that magnitude required precautions to be taken with both mud properties and BHA design to avoid differential sticking. The completion design included corrosion resistant alloy (CRA) for the unprotected pipe below the 7" liner top as well as for the 4-1/2" slotted liner covering the horizontal section.