bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric Permittivity of Shales as a Measure of their Physico-Chemical Sensitivity
Authors: Fam M.A. , Dusseault M.B. 
Published: December 2007

Abstract
The specific surface of particles' and the properties of the pore fluid control the sensitivity of shales to a given change in the host environment. In this study, dielectric permittivity measurements are suggested to assess the reactivity coefficient, which is a measure of the physico-chemical sensitivity of a clay-fluid system. The effects of specific surface and pore fluid properties on permittivity data are discussed using dielectric spectra of ideal systems and real shale cores. Normalized high-frequency real permittivity data and the percentage of free water (estimated using high- frequency imaginary permitivity spectra) are shown to decrease with the increase in the reactivity coefficient. Similarly, high low-frequency permittivity values normal to the bedding plane indicate systems with high reactivity coefficients. Vertical strains measured during osmotic consolidation tests confirm the previous trend. Finally, general guidelines are presented to help in identification of reactive systems using complex permiflivity measurements.
P. 285
Plasticity and Permeability in Carbonates: Dependence on Stress Path and Porosity
Authors: Yale David P. , Crawford Brian 
Published: December 2007

Abstract
Pore collapse and the plastic behavior of high porosity chalks is well known but the extent to which harder, more moderate porosity carbonates are plastic is not as clear. We have experimentally determined the elastic and plastic deformation and effect of that deformation on permeability for a suite of carbonate rocks spanning the porosity range of 14% to 42%. The depositional environment of the carbonates was a shallow marine reef with some secondary porosity development.
Biaxial compression tests were carried out along various stress paths where the ratio of axial to radial effective stress change was kept constant. Yield and failure surfaces and strain hardening response were mapped as a function of porosity. Variation in permeability and compressibility as a function of porosity, lithology, and stress path were determined. The results were modeled with a critical state-cap plasticity model.
The deformation of the carbonates generally followed a critical state cap model. The yield cap and hardening function were strongly dependent on porosity. Even moderate porosity samples (15-22%) showed significant plastic strain under stress conditions attainable in many petroleum reservoirs. The compressibility of the samples in the plastic regime was a strong function of both porosity and stress path.
One aspect of the observed deformation that did not fit critical state theory was the long transition from elastic to fully plastic behavior. We found we could represent this behavior with two cap surfaces: an initial yield surface and final hardening surface.
Permeability reduction was a strong function of stress path. Permeability reduced less for a given increase in mean stress along stress paths with higher differential stress increments. Permeability reduction due to compaction was offset by permeability enhancement due to microcracking depending on stress path and differential stress.
P. 485
Plastic Modelling Of Compressible Porous Chalk and Effect of Water Injection
Authors: Homand S. , Shao J.F. , Schroeder Ch. 
Published: December 2007

Abstract
According to many experimental investigations of porous chalk an elastoplastic model with two yield surfaces is proposed. The physical meaning of the parameters of the model and the method used for their determination are explained. Some laboratory tests are then simulated in order to validate the model. Hydrostatic compression tests are performed using different kinds of saturating fluid. The chalk responses obtained can be classified into two groups corresponding to two groups of fluids : water and oil. The dependency of chalk behaviour with saturating fluid is explained through the capillary effect and "wettability" of the fluid. A new approach for numerical modeling is proposed it is assumed that there are two chalk materials, oil and water saturated, superposed on the same material point. Some validation examples are presented.
P. 495
Investigation of the Poromechanical Behavior of Shales in the Elastic Domain
Authors: Vincke O. , Longuemare P. , Bouteca M. , Deflandre J.P. 
Published: December 2007

Abstract
In order to study the poroelastic behavior of shales, a set of experiments have been performed in an uniaxial strain setup. The shales were cored at a depth about 450m. Assuming Biot's poroelastic theory, the Biot coefficient was determined in a uniaxial strain loading system.
At several steps of the mechanical loading in the plastic domain, the poroelastic properties are determined, A particular attention is paid to the evaluation of the Biot tensor by combining the results of 2 different mechanical unloadings. One consists in decreasing the total stress, the other consists in increasing the pore pressure,
Since the shales are anisotropic rocks, measurements have been performed on samples cored perpendicular to the bedding plane or parallel to the bedding plane. Three different rock samples have been tested and measurements have been performed in both directions,
The Biot coefficient is shown to change while loading is increased, on the other hand no significant difference is observed as a function of the orientation with regard to the bedding plane.
P. 515
The Norne Accident - Safety in North Sea Helicopter Operations
Authors: Heiberg Gunnar 
Published: December 2007

Abstract
The Nome helicopter accident is the worst disaster in Statoils 25 years of operation. This paper gives a resume of the accident, search and rescue operations, investigation and follow-up. Supplementing this is an overview of traffic volumes, historical risk, risk analysis studies and safety initiatives for offshore helicopter operations in Norway.
Prevention of Shallow Gas Migration Through Cement
Authors: Al-Buraik Khalid , Al-Abdulqader Khalid , Bsaibes Riad 
Published: December 2007

Abstract
The problem of surface gas migration is a common and dangerous one. Its presence can prove to be not only a nuisance but more importantly a serious source of well control problems. Various solutions have been tried worldwide with differing rates of success. The problem of surface gas migration was encountered during the development of a field in Saudi Arabia. Detailed analyses of samples showed the gas to be mostly nitrogen coming from depths between 400 ft and 1000 ft. Several techniques were utilized to combat the problem including the use of conventional fluid loss, conventional gas migration slurry as well as changes in the casing design programs. The only successful solution involved the use of a novel low-temperature gas migration product coupled with several modifications in the drilling practices. This paper discusses the nature of the problem and the different techniques applied with a focus on the particulars of the only successful method.
Wellbore Stability Analysis and Guidelines for Efficient Shale Instability Management
Authors: Tan C.P. , Rahman S.S. , Chen X. , Willoughby D.R. , Choi S.K. , Wu B. 
Published: December 2007

Abstract
An efficient approach to wellbore stability analysis and management of shale instability by taking into consideration the dominant instability mechanism(s) has been developed. The mechanism(s) is dependent on the type of shale, in-situ stress environment and drilling fluid system used. These factors determine whether a drilling fluid program can be developed using a mechanical (stress-induced) wellbore stability analysis or complex time-dependent drilling fluid-shale interaction and thermal mechanisms need to be taken into account.
A range of wellbore stability analytical tools for efficient management of shale instability is presented. A pragmatic approach to use drilling fluid design charts together with a shale property database and property correlations for designing optimal drilling fluids to manage shale instability efficiently is described. The utilisation of the tools is demonstrated through a field case study in which strategies are developed to control wellbore instability in horizontal wells. Parametric analyses conducted demonstrate the effects of shale and drilling fluid properties on time-dependent wellbore (in)stability. They highlight the conditions in which the drilling fluid-shale interaction mechanisms are critical and need to be incorporated in the analysis.
P. 165
Lithology Diagnosis Based on the Measurements of Drilling Forces and Moments at the Bit
Authors: Ziaja M.B. , Roegiers J.-C. 
Published: December 2007

Abstract
Most real-time drilling interpretation is performed using some sort of normalized rate of penetration to infer changes in lithology and evaluate the condition of the bit. This frequently leads to ambiguous or confusing results, because it is impossible to separate all bit effects from lithology effects using only one measurement. Also, no method exists to evaluate drill bit performance such as directional responsiveness and steerability. This paper proposes a new model of bit performance evaluation and shows how the force and moment measurements can be used to separate the bit effects from the lithology effects when drilling with PDC bits.
Analytical results of rock/bit interaction modeling are based on the laboratory drilling force measurements during rock comminution with a PDC cutter. It was found that a given rock/PD C system results in the specific relationship between axial and tangential drilling forces. This empirical relationship is used to determine the distribution of drilling forces and moments on a generic conventional PDC bit. Then, it is shown how the measurements of force and moment generated during drilling can be used in bit wear and lithlogy changes evaluations. This model accounts for abrasive wear of the cutters and detects those that are exposed to more severe loads. Thus, it may be also used as a guide in bit selection and bit design modifications.
If verified in the harsh economic environment of today, field application of the method should lead to a better understanding of downhole conditions and a more accurate decision as to what direction a bit is drilling, when to pull out bits, and thus to a reduction of drilling costs.
P. 185
Evaluation of Bit Performance Using An Advanced Drilling-Test-System
Authors: Xu H. , Hatakeyama T. , Yonezawa T. , Suzuki A. 
Published: December 2007

Abstract
Japan National Oil corporation (JNOC) has been in possession of an advanced Drilling-Test-System (DTS). This DTS can be used for full-scale indoor experiments and a series of tests on the rocks of Mudstone, Volcanic tuffs and Sandstone have been conducted by using it. The bit types used for those tests included PDC bit, Insert-tricone bit and Surface set Diamond bit. Bit performance is evaluated based on the values of the Rate of Penetration (ROP) and the impact on ROP of individual drilling variables. As a result, it is found that in comparison, the employed PDC bit appeared to be the most suitable bit for drilling on the rocks used for the tests. Meanwhile, tests using Water as drilling fluid were conducted and the results indicated that ROP and drillability could be significantly enhanced by improving the cleanness of bit and in-situ of bit. An embryonic model for PDC bit has been developed and verified to a certain extent. Further tests and analyses are still ongoing and it is expectable that, the results from the DTS test will significantly benefit to practical drilling optimization including bit selection, optimizing drilling and hydraulic parameters and diagnosing drilling problems.
Riser Lift Pump for Deep Water Drilling
Authors: Sangesland S. 
Published: December 2007

Abstract
A new riser system consisting of a lift pump located a distance down in a conventional marine drilling riser with a separate mud return line from the lift pump and up is used to reduce the hydrostatic head of the drilling fluid in the bore hole. The upper section of the riser above the pump outlet is vented to the atmosphere. A lower mud level allows a higher mud weight to be used. However, determined by the position of the fluid level it will result in a lower pressure at the casing shoe. The hydrostatic head of the drilling fluid and the seawater will be sufficient to control the bottom hole pressure after an emergency disconnection of the marine-drilling riser at the seabed. The riser joint which houses the pump can be located anywhere in the riser section depending on water depth, formation pore pressure etc., typically 200 - 300 m below the sea level. The system also allows the bottom hole pressure to be quickly adjusted by simply adjusting the air/mud level above the pump outlet in the marine-drilling riser.
P. 299
Applications of a Near Surface Disconnectable Drilling Riser in Deepwater
Authors: Kogure E. , Ohashi M. , Urabe S. , Tanabe A. 
Published: December 2007

Abstract
For deepwater offshore drilling operations, planning and operations must take into account the necessary time required to pull the drilling riser in case of an emergency. Operational limitations prevent the complete recovery of the riser prior to location evacuation, and physical limitations may cause a riser to stress fail catastrophically if hung off. Uncertainties in predicting the size and course of storms combined with the above limitations severely restrict the operational envelope of deepwater riser drilling. Both operators and contractors would benefit from a system that would allow a riser to be abandoned and later re-entered easily in deepwater.
P. 331
Evaluation of Viscous Oil-Bearing, Water Flooded Reservoirs
Authors: Olesen Jean-Rémy , Liu Chengbing , Zeng Wenchong , Mao Keyu , Zhang Zongjian 
Published: December 2007

Abstract
In this North China Basin field, the evaluation of newly drilled in-fill wells oil saturation, capillary-bound water volume and permeability is difficult. Conventional saturation evaluation is hampered by constantly varying water salinities due to the fresh water flooding EOR program. NMR-derived effective porosity, capillary-bound water volume and permeability are adversely affected by the extreme viscosity of the crude oil.
This paper presents a synergistic evaluation approach, combining conventional open hole data with NMR data corrected for viscous oil effects and cased hole gamma-ray spectroscopy data for complete evaluation of Phie, Sw, Sxo, Swirr and Kint. A new technique is developed to derive Sxo exclusively from NMR data and clay volume.
This synergistic approach overcomes salinity and crude oil viscosity problems, it also allows more accurate lithology and reservoir producibility estimation, but, the Sxo derivation from NMR data is only valid if crude viscosity is very high.
Fluid Placement Model for Horizontal Well Stimulation
Authors: Eckerfield L. D. , Zhu D. , Hill A. D. , Robert J. , Bartko K. 
Published: December 2007

Abstract
Acidizing is a common method of stimulating horizontal wells. The acidizing process is fundamentally different when applied in a horizontal well compared with application in a vertical well. The fluid distribution in a horizontal well is affected by a longer wellbore length, a broader variation in the reservoir properties along the wellbore, and possibly different mechanical means to place the fluids in the wellbore. A comprehensive fluid placement model linked with a reservoir acidizing simulator is essential to precisely design acidizing treatments for horizontal wells.
This paper presents a model of fluid placement in a horizontal well. The model predicts the placement of injected fluids by tracking the interfaces between different fluids in the wellbore. It is capable of tracking multiple interfaces for multiple injection stages in horizontal wells. For injection with coiled tubing, the model allows tubing tail movement during injection. It also handles simultaneous injection from the annulus and from a tubing string. The fluid distribution generated from the model can be used as input information in a reservoir acidizing model for sandstone acidizing design. Both analytical and discretized solutions of the model are presented in the paper. Examples in the paper illustrate the effects of such factors as velocity of tubing movement, annular injection, and a non-uniform distribution of flow into the reservoir on fluid placement in an acidizing treatment.
The fluid placement model can help to determine optimum tubing tail locations and optimal injection volumes of acids, to select the most appropriate diverting methods, and, hence, to maximize the benefits of an acidizing treatment.
Flexible 3.5in. O.D. MWD System Enhances Short Radius, Horizontal Drilling Applications in Shengli Oilfield, China
Authors: Hongwei Li , Page S. C. , Zhenghu Wang , Knight J. H. 
Published: December 2007

Abstract
A 3.5in. O.D. MWD system has been developed which is capable of providing Directional and Gamma Ray services in short radius wells at build rates up to 3.3°/meter, a build rate that had not previously been available through conventional MWD technology. Specially selected materials, innovative tool joint design and an integral MWD Transmitter/Drilling sub-assembly have been utilised in order to withstand the stresses associated with high build rates while maintaining full functionality in small diameter drill collars. Innovative testing methods were required to qualify the system for short radius applications, resulting in the implementation of significant design improvements.
Utilising the new MWD system with short radius drilling technology has opened up the possibility of horizontal re-entry of existing wells completed with small diameter casing. Three case histories in the Shengli Oilfield are presented. The three re-entry wells, Y-CP1, X-CP1 and L-CP1 had originally been completed in 139.7mm casing. Two of the re-entry wells were kicked off through 2.1meter casing windows using oriented whipstocks with 118mm and 121mm bits at 3235 and 2109 meters respectively. Well L-CP1 section milled 18 meters of casing then side-tracked and built angle, reaching a TD of 2906 meters measured depth. Build rates for the wells averaged 2.0°/meter with a maximum of 3.3°/meter. Maximum horizontal reach was 151 meters from landing point.
Performance of the drilling and MWD systems was excellent during the drilling phase of the wells. Using the knowledge and experience gained it will be possible to utilise the equipment to re-complete and extend the life of the numerous wells that have been completed in small diameter tubing in the Shengli area. Well designs can be planned that could not have been considered using conventional technology. Significant production gains will be made as a result.
Casing Shear: Causes, Cases, Cures
Authors: Dusseault Maurice B. , Bruno Michael S. , Barrera John 
Published: December 2007

Abstract
Casing impairment leads to loss of pressure integrity, pinching of production tubing, or an inability to lower workover tools. Usually, impairment arises through shear because of displacement of the rock strata along bedding planes or more steeply inclined fault planes. These displacements are shear failures triggered by stress concentrations generated by volume changes because of production or injection activity. Volume changes arise from pressure changes, temperature changes, or solids movement (solids injection or production).
Dominant casing deformation mechanisms are localized horizontal shear at weak lithology interfaces within the overburden; localized horizontal shear at the top of production and injection intervals; and, casing buckling within the producing interval, primarily located near perforations.
Mitigating casing damage usually means reducing the amount of shear slip or finding a method of allowing slip or distortion to occur without immediately affecting the casing. It is seldom that strengthening the casing-cement system will eliminate shear, although in some circumstances it may retard it. Proper well location or inclination, under-reaming, special completions approaches, reservoir management and other methods exist to reduce the frequency or rate of casing shear.
Multilaterals Convert 5 Spot to Line Drive Waterflood in SE Utah
Authors: Hall Scott D. 
Published: December 2007

Abstract
Horizontal technology has increased rapidly since the late 1980's. Most horizontal wells drilled in the U.S.A. have been in primary recovery applications. However, horizontal technology can be modified and applied to secondary recovery operations to improve sweep efficiency and recovery over vertical wells.
This case history reviews four years of a multilateral horizontal drilling program at the Aneth Unit and updates Ref 1 and 2. Multilateral drilling has converted parts of the Aneth Unit from 5-spot to line drive waterflood patterns. Drilling horizontal in both producing and injection wells with laterals parallel to each other may improve oil recovery by 15% of the OOIP in the zones horizontally drilled at the Aneth Unit. However, not all zones and not all parts of the field are economic for horizontal drilling. From late 1994 through early 1998, 143 laterals were drilled and completed as re-entries from 43 vertical wells (23 producing and 20 injection). Those 43 wells were drilled 214,000 feet from kick-off to total depth. Of the 214,000 feet drilled, 180,000 feet was pay. All 379 previous vertical wells drilled only 26,000 feet of pay. Horizontal drilling exposes magnitudes more of the pay zone to the wellbore.
3-D Geopressure Analysis
Authors: Kan T. K. , Kilsdonk B. 
Published: December 2007

Abstract
In clastic sedimentary basins, geopressure is controlled by depositional and diagenetic history as well as structural geometry. The shapes and sizes of pressure compartments depend on the 3-D structure and distribution of lithologies and faults. We developed 3-D geopressure analysis algorithms and methodology which enable interpreters to estimate, analyze, and visualize geopressure in 3-D. Potential benefits include: (1) more accurate pre-drill pore pressure prediction; (2) 3-D definition of pressure compartments; (3) enhanced interpretation of fault seal or leak from pore pressure distribution; (4) enhanced interpretation of fluid migration pathways. Careful velocity analysis after pre-processing of the 3-D pre-stack seismic data produces 3-D RMS velocities at every in-line and cross-line position through a volume. Further lateral smoothing removes velocity errors caused by near surface and acquisition noises. An interval velocity volume is generated from the smoothed RMS velocity volume. Calibration using offset wells is used to transform 3D seismic velocity into 3D pore pressure gradients. In addition, we have also developed an algorithm to generate minimum horizontal stress. Using difference of the minimum horizontal stress and pore pressure, we can calculate an effective stress volume. This is extremely important for casing design and evaluating seal integrity of the prospect.
We have generated and analyzed several 3-D geopressure cases in deep water Gulf of Mexico and South China Sea. Relationship between fluid pressure, faults and geometry can be visualized and interpreted inseveral ways: (1) a pressure volume may be combined with amplitude slices - this is best for understanding and visualizing the influence of subtle structures; (2) a pressure volume may be combined with interpreted fault surfaces to visualize the effects of major faults; (3) Interpreted fault slices may be combined with seismic geopressure lines. Pressure volumes are best viewed as part transparent, part translucent, and part opaque.