bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Eccentricity, Voids, Cement Channels, and Pore Pressure Decline on Collapse Resistance of Casing
Authors: Berger A. , Fleckenstein W. W. , Eustes A. W. , Thonhauser G. 
Published: December 2007

Abstract
Conventional collapse design is based upon uniform external pressure loading. Conventional design considers pore pressure and does not account for the effects on casing stresses from the external cement sheath and surrounding formation. In addition, the conventional design does not predict the collapse load of non-uniform loaded casing that arises from imperfect cement jobs and formation voids.
This paper presents the results of a finite element study of casing subjected to external, non-uniform loading. These loads include the effects of cement channels and voids, surrounding formation voids, and pore pressure decline in those voids. A better understanding of these common downhole conditions will help to better understand the resultant stress fields and enable a more accurate determination of the necessary collapse strength of casing.
Accelerating Drilling Technology with eKnowledge Factory: A Changing Paradigm
Authors: Samuel G. Robello , McColpin Glenn 
Published: December 2007

Abstract
This paper summarizes the underlying process involved in increasing the efficiency of a drilling organization through use of knowledge management and technology at a time when the knowledge base of the drilling industry is eroding and the wells per engineer are increasing. The eKnowledge factory depicts a virtual space in which drilling knowledge created is captured and stored in different buckets for distribution and reuse. It is stored by way of knowledge insertions at various stages of field development in a corporate environment. Stored knowledge can be shared across an organization. In this paper, we present various statistical data about the graying workforce in the drilling industry and discuss highlights of the results. Based on the findings we discuss three major stages of eKnowledge factory development: operational, engineering and strategic. The relationships between discrete drilling engineering analyses and the ability of modern digital technology to dynamically interact with these engineering models will be presented with examples. Also the bane of the graying work force and boon of the knowledge insertions, mining and tracking will be discussed. The ultimate premise of this paper is that through proper preparation and use of technology, something like eKnowledge factory can allow organizations to overcome the demo graphic's battle that the petroleum industry is facing in coming years.
Evaluation of Pipeline Configurations with Active Heating for Export of Waxy Crude Oil
Authors: Fleyfel Fouad , Hernandez Oris , Sturgis Rusty , Meng Weihong 
Published: December 2007

Abstract
Insulation and active heating options evaluated for transportation of waxy crude oil in an 8-inch flowline from a platform 10 miles offshore. Two bundled pipeline configurations are studied, and the results are compared with conventional pipe-in-pipe and a non-jacketed insulated pipe. The crude has a high pour point (PP, 91 °F) and a high wax appearance temperature (WAT, 105°F).
A solution is provided that allows the crude to stay above WAT. The non-jacketed pipe option is not thermally efficient; the pipe-in-pipe option can keep the crude oil warm during normal flow; but high storage capacity is required at the platform, which makes the solution impractical. The bundled pipeline configurations maintain the crude oil temperature above WAT thus avoiding waxing and gelling during steady state flow and during restart operations.
Despite being more expensive, the bundled pipeline configuration proved to be the right solution for this particular field. The results of this study are applicable for evaluations of similar field developments.
Streamline-Based History Matching Using Geostatistical Constraints: Application to a Giant, Mature Carbonate Reservoir
Authors: Gross H. , Thiele M. R. , Alexa M. J. , Caers J. K. , Kovscek A. R. 
Published: December 2007

Abstract
This paper describes the combined use of streamline and geostatistical sequential simulation to a Middle Eastern reservoir with a long production history and a significant number of wells.
In the algorithm presented, streamlines are used to delineate drainage regions for producers that are to be history matched. The time-of-flight of the streamlines is used to establish the relationship between historical rate mismatch and permeability of the drainage region. Rather than correcting permeability directly, we use the corrections supplied by the streamlines to constrain the geostatistical algorithms and thereby ensure a consistent geological scenario at every iteration in the process.
Before applying the methodology to a real field case, we use a simple synthetic example to explain the main points. Finally, we show the application of the history-matched model for evaluating an infill well prospect and how streamline simulation and finite-difference simulation are used as complementary tools to increase the predictive power of the numerical model of the reservoir.
Impact of Drilling Activities in Warm Sea: Seabed Re-Colonization
Authors: Dalmazzone C. , Blanchet D. , Lamoureux S. , Durrieu J. , Camps R. , Galgani F. 
Published: December 2007

Abstract
Since the onset of offshore drilling, the drill cuttings and their disposal have received much attention in the oil and gas industry. Numerous studies performed in the laboratory on the foreseeable fate of cuttings have led to the search for new formulations with the objective of achieving lower toxicity and better intrinsic biodegradability.
The study of the marine environmental impact associated with the discharge of OBM (oil base muds) drill cuttings has already given rise to numerous works and surveys related to the North Sea, but it is clear that knowledge is still limited. Further information is required on the monitoring of sediments polluted with OBM cuttings, especially in warm sea conditions.
On this topic, a research project was conducted in 2002 and 2003 in Congo (Africa) in order to study the modes of regeneration of the benthic fauna and the recolonization of the seabed after the discharge of OBM cuttings. Previous sampling and analyses were performed in 1995 (after the first step of drilling) and 2000 (one year and a half after the stop of cuttings discharge). In 2002, a systematic study of the abundance and diversity of the benthic fauna was conducted. In addition, a methodology based on classical physical chemical analyses on sediment, tests of toxicity, biodegradability and lixiviation was applied, in order to explain the evolution of the recolonization by the benthic fauna (SPE 77471). In the more general context of the environmental constraints of oil industry, our work demonstrated the containment of the impacted zones, the absence of significant risks of modification of the adjacent ecosystems and the possible application to other discharge sites.
We present here the results related to the last phase of sampling carried out in 2003. It is noteworthy that the whole results confirm the main evolutions observed in the previous survey.
Measurement and Theory of Gas Trapping in Porous Media During Steady-State Foam Flow
Authors: Tang Guo-Qing , Kovscek Anthony R. 
Published: December 2007

Abstract
Aqueous foams are useful to reduce gas mobility during steam or CO2 flooding and for aquifer remediation. Trapped or stationary gas contributes significantly to the extent of gas mobility reduction. There is no consensus regarding the functional dependence of trapped gas fraction, or conversely the flowing gas fraction, but it is believed to vary with pressure gradient, pore geometry, foam-bubble size (i.e., texture), surfactant type, and concentration. This work uses a gas-tracer technique in combination with X-ray CT scanning to measure the fraction of flowing gas and the in-situ aqueous phase saturation during steady-state foam flow in Berea sandstone. Statistical network concepts are used to interpret the mechanisms that govern the mobile gas fraction.
The experiments show that as gas velocity increases, the flowing gas fraction of the foam increases. Similarly, as injected gas-liquid ratio increases, the fraction of gas flowing increases. Hence, the absolute velocities of gas and aqueous surfactant solution are fundamental to foamed-gas mobility reduction. Effluent foam-bubble sizes were measured in a visualization cell installed at the core outlet. Bubbles range in size from about 60–120 μm in diameter. The smaller the effluent bubble size, the less the fraction of mobile gas. Lastly, experiments show that as surfactant concentration increased, the flowing gas fraction decreased.
While it is likely that an empirical correlation could be deduced from the experimental results, such an approach does not engender a mechanistic understanding of the role of the various parameters. Instead, statistical network theory is employed incorporating the parameters identified as important in the experimental program: pressure gradient and bubble size. A closed form expression is developed for the fraction of mobile gas. It is predicted that the fraction of gas flowing is a weak function of pressure gradient, foam-bubble size, and the permeability of the porous medium. Moreover, the theory shows excellent ability to reproduce the newly obtained experimental data
Water Saturation Estimation Using Equivalent Rock Element Model
Authors: Shang Bruce Z. , Hamman Jeffry G. , Caldwell Donald H. 
Published: December 2007

Abstract
The second Archie equation relates water saturation to formation resistivity index by a power function. This important relationship has been widely used to evaluate hydrocarbon saturation. However, many rocks don't obey this empirical rule. The best Archie fit to these data may not comply with physical bounds and create significant bias in computed hydrocarbon saturation.
This paper develops a new method for water saturation estimation based on the equivalent rock element model (EREM) that has been demonstrated to work well for rock transport properties to the first order effect. EREM contains two orthogonal pore components, one parallel and the other perpendicular to the direction of transport. Pore structure efficiency is defined as the volume ratio between the two components. When pores contain conductive and non-conductive fluid phases, the pore structure efficiency for the conductive phase changes with saturation due to fluid and mineral properties and pore structure variations. Approximating conductive phase pore structure efficiency as a function of saturation, we formulated a theoretical relationship between resistivity index and water saturation. The conductive phase may become discontinuous below a certain critical saturation due to pore structure, wetting characteristics, interfacial tension or a combination of different factors. The proposed algorithm readily incorporates this critical saturation phenomenon and explains the empirical relationships between resistivity index and water saturation for both Archie and non-Archie rocks. It fits core measurements better than Archie's second equation as demonstrated in our real examples and provides more accurate estimation for water saturation. This new approach expands the applications of the equivalent rock element model.
PCP Axial Load: Theory and Lab Results
Authors: Alhanati F. J. S. , Skoczylas P. 
Published: December 2007

Abstract
Accurate estimation of pump axial load in Progressing Cavity Pump (PCP) applications is an important aspect of the installation design. It affects the calculation of rod stresses, and therefore the determination of the rod string torque capacity. In deviated wells, it also directly affects the calculated rod-tubing contact loads, and therefore the evaluation of wear related issues.
This paper discusses the current theory related to the calculation of axial load in PCP applications, in light of laboratory test results obtained with 25 different pump models.
The axial load is normally estimated by multiplying the differential pressure across the pump by an effective pump cross sectional area. However, given the complexity of the pump geometry, it is not straightforward how to properly calculate this effective area. In the paper, it is shown that intuitive choices, such as the circle defined by the rotor minor diameter, the circle defined by the rotor major diameter, or the pump cavity area, do not yield adequate results.
A new method is suggested that not only matches quite well the extensive laboratory data for single-lobe pumps but also matches reasonably well the limited data available for multi-lobe pumps.
Estimation of Saturation Pressure through Wellbore Measurements
Authors: Millán Arcia Einstein , Rodriguez F. , Madail W. 
Published: December 2007

Abstract
Reliable fluid property data is always required in reservoir description. Normally, the most accurate fluid data is available from PVT studies, based on surface or bottomhole collected fluid samples. Specifically for Gas Condensate systems, fluid sample reliability poses a strong challenge mainly due to thermodynamic-instability-related problems. Very often, due to the extremely low liquid to gas ratio, even in high yield fluids, inaccuracies related to surface sampling links to erroneous results in PVT data. Despite recent advances in pressure compensate bottomhole fluid samples, temperature dependency yielding to phase envelope migration poses a strong challenge.
Tedious and time consuming laboratory procedures adversely impact field operations and hence final operating costs. Without implying to substitute laboratory results, a simplistic approach has been developed to determine saturation pressure based on easily acquired downhole wellbore data. The method involves basic flowing pressure versus depth sensor-gauge-data to estimate the dynamic gradient derivative, and offers a fast, reliable, and inexpensive approach to identify saturation pressure, fluid segregation and convection events in under saturated reservoirs. Actual PVT and dynamic gradient data belonging to gas condensate reservoirs were used. Measured saturation pressure was available for two of the three wells evaluated. The fluid data was validated and reproduced by means of the PVTi Eclipse module. PVT consistency verification was performed via, well completion, and production data, mass balance and thermodynamic stability checks. Results suggest good match between the PVT and dynamic gradient derived saturation pressure values.
Fracturing Fluid Viscosity Profiles Determine Well Productivity in a Remedially Stimulated Tight Gas Reservoir
Authors: Miller Jason D. , Ponto David A. , Reasoner Scott J. 
Published: December 2007

Abstract
Since 1998, over 4000 wells completed in the low-permeability Codell formation of the 300,000 acre Wattenberg Field in northeast Colorado have been remedially stimulated with massive hydraulic fracturing treatments. This remedial program has been extremely successful. A majority of the refracturing treatments in this study have yielded higher oil and gas rates than experienced following the original treatment, performed many years previously. Fluid and proppant volumes of the remedial treatments have been very similar, but certain characteristics of the fracturing fluid correlate significantly with variability in well productivity. The main correlating parameter has been the fracturing-fluid viscosity profile (FVP), which is defined by the early-time rate of viscosity buildup, the peak viscosity developed, and the rate of viscosity degradation following the peak. For each treatment, the FVP has been evaluated with a HTHP (high temperature/ high-pressure) rheometer, using a shear and thermal history representative of the Codell treatments. Within the Wattenberg Field, there is evidence that FVP has a multi-faceted impact on well productivity that is more than just being able to place the proppant into the formation.
Interfacial Interactions of Crude Oil-Brine-CO2 Systems under Reservoir Conditions
Authors: Yang Daoyong , Gu Yongan 
Published: December 2007

Abstract
In this paper, an experimental technique is developed to study the interfacial interactions of the crude oil-brine-CO2 systems at different pressures and temperatures. The major component of this experimental set-up is a see-through windowed high-pressure cell. By using the axisymmetric drop shape analysis (ADSA) for the pendant drop case, this new technique makes it possible to determine the interfacial tension (IFT) and to visualize the interfacial interactions among the crude oil, brine and CO2 under practical reservoir conditions. More specifically, the equilibrium IFT of the crude oil-CO2 or the brine-CO2 system is measured as a function of pressure and temperature, respectively. For the crude oil-CO2 system, there always exists a constant low IFT (i.e., the partial miscibility) as long as the pressure is higher than a threshold value. No ultra low or zero IFT between the crude oil and CO2 is found at the operating pressures and temperatures tested in this study. For the brine-CO2 system, the complete miscibility between the brine and CO2 can be achieved. In addition, a number of important physical phenomena are observed after the crude oil or brine is made in contact with CO2. In particular, the swelling effect, light-ends extraction, initial turbulent mixing and wettability alteration are the major characteristics of the crude oil-CO2 system, whereas the swelling effect and the complete miscibility are the primary features of the brine-CO2 system. For the crude oil-brine-CO2 systems, wettability between the crude oil and the stainless steel needle in CO2-saturated brine phase is rather different from that of the crude oil-CO2 system. This wettability difference may considerably improve the oil recovery in a previously waterflooded water-wet reservoir during CO2 flooding processes. The immiscibility between the crude oil and CO2-saturated brine phase is still observed up to P=28.196 MPa and T=58°C.
Interpretation of Borehole Measurements Acquired in Laminated Clastic Sequences Subject To Mud-Filtrate Invasion
Authors: Chowdhury Subhadeep , Torres-Verdín Carlos , Mezzatesta Alberto 
Published: December 2007

Abstract
The effect of mud-filtrate invasion on resistivity, nuclear, and formation tester wireline measurements is poorly understood when the formation of interest is laminated on a scale below the vertical resolution of borehole logging instruments. This paper describes a quantitative study to assess the effect of mud-filtrate invasion on well-log measurements acquired in thinly laminated clastic sequences.
Synthetic models are constructed with varying proportions of shale and two types of sand. These models are used to simulate the process of mud-filtrate invasion. Each type of sand is assumed isotropic, homogeneous, water wet, and saturated with oil to the level of irreducible water saturation. Simulations of the process of mud-filtrate invasion yield 2D cross-sections of water saturation, salt concentration, and electrical resistivity in the invaded rock formations. These cross-sections are then used to simulate wireline resistivity, density, neutron, and formation tester measurements. Using standard interpretation techniques, saturation of original oil in place is calculated with all the simulated log measurements.
Results indicate that for laminated sandy and shaly sand rock formations, induction (electrical resistivity), nuclear (porosity), and formation pressure tester (pressure) measurements are significantly affected by both the relative proportion of lithology and the invasion of mud filtrate. Water saturation in a laminated sandy rock formation can vary significantly when calculated with saturation and porosity exponents perpendicular and parallel to the bedding plane, respectively. Permeability calculated from dual-packer formation tester measurements can significantly depart from the effective average permeability in a composite and laminated sandy formation.
Conventional induction resistivity instruments cannot distinguish between resistivities in the flushed and invaded zones when the volume of shale is higher than 50%. Presence of shale also causes a significant error in the estimated permeability.
Application of a New Mechanistic Decline Curve Method to Kern County Oil Fields
Authors: Reyes Jericho L. P. , Li Kewen , Horne Roland N. 
Published: December 2007

AbstractField production data from Kern County acquired from the California state database was analyzed for production decline. A decline curve methodology based on fluid flow mechanisms was used. The model reveals a linear relationship between the oil production rate and the reciprocal of the oil recovery. Existing decline curve methods often either overestimate or underestimate reserves, and are mostly empirical in origin. The current approach not only provides a method to estimate reserves, but because of its basis on fluid flow mechanisms, can also be used to infer regional reservoir properties that may be useful in production decisions.Oil wells from six producing oil fields in Kern County were analyzed using this decline curve method and two parameters, a0, the production rate index, which measures the recovery rate, and b0, the gravity index, were mapped regionally. Since the two parameters are associated with capillary pressure and relative permeability, conclusions can be made about the geological properties of the reservoirs from the derivation of the a0 and b0 parameters. This will aid in determining which regions are more prolific, and provide a correlation based on physics to infer reserves, and reservoir rock and fluid properties. It was found that fields with higher a0 and b0 values have higher oil recovery.This study demonstrates the applicability of this decline curve analysis and provides an alternative to empirical methods.
Real Time Optimization: Classification and Assessment
Authors: Mochizuki S. , Saputelli L. A. , Kabir C. S. , Cramer R. , Lochmann M. J. , Reese R. D. , Harms L. K. , Sisk C. D. , Hite J. R. , Escorcia A. 
Published: December 2007

AbstractThe Real-Time Optimization Technical Interest Group (RTO TIG) has endeavored to clarify the value of real-time optimization projects. RTO projects involve three critical components: People, Process, and Technology. Understanding these components will help to establish a framework for determining the value of RTO efforts. In this paper, the Technology component is closely examined and categorized. Levels within each Technology category are illustrated using spider diagrams, which help decision-makers understand the current status of operations and the impact of future RTO projects. Uncertain value perception in our industry has been one of the critical issues in adopting RTO systems. Therefore, case histories are reviewed to demonstrate the impact of RTO projects.To assist RTO project promotion, we list lessons learned through case histories, suggest a justification process, and present a simple economic example.