bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Dynamic Filtrate Loss During the Drilling of a Horizontal Well With High-Permeability Contrasts and Its Impact on Well Performance
Authors: Wu Z. , Vaidya R. N. , Suryanarayana P. V. 
Published: June 2010

Summary
In this paper, we present a new approach for modeling filtrate invasion during the drilling of a horizontal well through regions with high-permeability contrasts, such as those caused by fractures and high-permeability streaks, and the impact that the cleanup of this approach has on well performance. The approach incorporates the drilling schedule and experiment-based dynamic filtrate-loss data into a fine-grid multiphase reservoir simulator. Unlike the traditional leakoff model, which assumes piston-like displacement in the filtrate-invaded zone, fluid flow in the invaded and the reservoir zones is described by the use of more-realistic two-phase water/ gas flow equations. The equations are solved under the dynamic boundary conditions of the leakoff model and time-varying reservoir exposure from drilling, tripping, completions, and work-overs. Because the impact of fractures on both invasion and flowback is more pronounced in low-permeability (tight) formations, the focus of this paper is on such formations.
In overbalanced drilling, the initial dynamic mudcake formation is critical in controlling filtrate loss. A dynamic fluid-loss model, which reflects the spurt loss and non-Darcy and non-Newtonian characteristics of filtrate flow through the mudcake is coupled with the reservoir simulator. Mud properties and different events during drilling influence compression, dynamic deposition, and erosion of the mudcake. The application of the dynamic filtrate-loss model avoids the complexity in building a multiparameter mathematical mudcake model without loss of generality. As in previous work, parameters in the dynamic filtrate-loss model are based on special core tests.
In existing experiments, leakoff coefficients are measured only for the matrix. The extrapolation of the dynamic leakoff coefficients for simulation of fluid loss into intersecting fractures is discussed. Driven by Buckley-Leverett equations, theoretical analysis is presented to emphasize the quantitatively spatial correlation between the invaded-filtrate saturation and the spatial permeability reduction in the invaded zone. The influence of water blocking, relative permeability alteration, and damaged permeability variation on well performance is simulated. A horizontal-well example is used to illustrate the flexibility of this approach, and the results are discussed in the context of well performance.
Control-Relevant Upscaling
Authors: Vakili-Ghahani S.A.. A. , Jansen J.D.. D. 
Published: June 2010

Summary
The conventional reason for upscaling in reservoir simulation is the computational limit of the simulator. However, we argue that, from a system-theoretical point of view, a more fundamental reason is that there is only a limited amount of information (output) that can be observed from production data, while there is also a limited amount of control (input) that can be exercised by adjusting the well parameters; in other words, the input/output behavior is usually of much lower dynamical order than the number of grid-blocks in the model. Therefore, we propose an upscaling approach to find a coarse model that optimally describes the input/output behavior of a reservoir system. In this control-relevant method, the coarse-scale-model parameters are calculated as the solution of an optimization problem that minimizes the distance between the input/output behaviors of the fine- and coarse-scale models. This distance is measured with the aid of the Hankel or energy norms, in which we use Hankel singular values as a measure of the combined controllability and observability and Markov parameters as a measure of the response of the system, respectively. The method is particularly attractive to scale up simulation models in flooding-optimization or history-matching studies for a given configuration of wells. An advantage of our upscaling method is that it relies most heavily on those parameter values that directly influence the input/output behavior. It is a global method in the sense that it relies on the system properties of the entire reservoir. It does not, however, require any forward simulation, either of the full or of the upscaled model. It also does not depend on a particular control strategy but instead uses the dynamical system equations directly. Its dependency on well locations, however, implies that it should be (partially) repeated when those locations are changed. We tested the method on several examples and, for nearly all cases, obtained coarse-scale models with a superior input/output behavior compared to common upscaling algorithms.
Dynamic Buckling and Snaking Motion of Rotating Drilling Pipe in a Horizontal Well
Authors: Gao Guohua , Miska Stefan 
Published: June 2010

Summary
This paper is a focused theoretical and experimental study on the dynamic buckling and snaking motions of rotating pipe in a horizontal well. First, a comprehensive dynamic buckling model is presented. As part of this model, a group of fourth-order nonlinear partial-differential equations is derived and discussed. Then, a perturbation solution of the model is obtained that represents the snaking motion of the rotating pipe. On the basis of the perturbation solution, critical dynamic buckling load and dynamic behavior of rotating pipe are analyzed. It has been found that there are two different kinds of snaking motion. In one type, the pipe moves up and down around its static buckling configuration. In the other type, the pipe moves from one side of the wellbore to the other side.
The authors also conducted an experimental study with a small- scale experimental facility. Depending on axial compressive load and rotating speed, different motion patterns of drilling pipe are observed. Measurements of axial load at both ends and axial displacement at the loaded end are recorded. These observations and measurements provide us with very important information about the dynamic behavior of rotating pipe in a horizontal well. Observations also show that the pipe may take two different patterns of snaking motions. Both critical static buckling load and dynamic buckling load were measured with this facility. Both theoretical and experimental results show that pipe rotation does not affect the critical load of dynamic buckling. Experiments also show that there exist two different kinds of snaking motions, which support the analytical solution of the dynamic model presented in this paper. The results are useful for practical design applications related to calculation of buckling loads and selection of bottomhole-assembly (BHA) elements and pipe rotational speeds.
Case Study: Production Data and Pressure Transient Analysis of Horseshoe Canyon CBM Wells
Authors: Clarkson C.R. 
Published: June 2010

Abstract
The Horseshoe Canyon (HSC) CBM play of the Western Canadian Sedimentary Basin is unique to low-rank coal reservoirs because of lack of water production; the production characteristics are qualitatively similar to conventional low-pressure dry gas reservoirs. However, the complex geological history of the coals and non-coal interbeds has imparted strong vertical and lateral heterogeneities that make the play difficult to characterize using conventional methods.
Recently, advances in production data analysis (PDA) methodologies have been made for CBM wells; techniques developed for conventional oil and gas reservoirs have been adapted by incorporating some CBM reservoir properties. For example, the popular flowing material balance (FMB) technique, as well as production type-curve and pressure transient analysis (PTA) have been modified to include relatively simple CBM reservoir behaviour (ex. equilibrium desorption). These methods, however, are primarily restricted to the analysis of single-layer reservoirs; significant errors in estimates of original-gas-in-place (OGIP) and other reservoir properties may occur if strong contrasts exist from layer-to-layer. In this work, multi-layer analysis tools are discussed, including analytical simulators that are used to history-match layer-allocated rates and pressures, and layer-specific FMB, which is used as a PDA method for individual layers.
The applicability of advanced PDA methods to the quantitative assessment of HSC reserves was investigated. Single-layer and multi-layer analysis tools were first tested against simulated data. Next, single-layer-equivalent analysis was performed on &gt;40 real wells using type-curve, FMB, and analytical simulation. Finally, a more rigorous multi-layer analysis was performed on a subset of wells where spinner surveys and individual-seam pressure buildup data were available. Analysis of these wells included PTA of the individual seams, individual seam material balance, and multi-layer analytical model history-matching of total commingled flow rates, individual coal zone rates estimated from spinner surveys and shut-in pressures. The single-layer- equivalent analysis appears to yield conservative estimates of OGIP compared to the more rigorous multi-layer analysis in the cases analyzed.
Future work will include continued comparisons of multi-layer vs. single-layer PDA, investigation of additional constraints on input reservoir properties used in multi-layer history-matching process, and time-lapse PTA work to quantify changes in layer permeability and skin during depletion.
Polymer-Flood Modeling Using Streamlines
Authors: Thiele M.R.. R. , Batycky R.P.. P. , Pöllitzer S.. , Clemens T.. 
Published: June 2010

SummaryThe successful design of a polymer flood relies on the ability to properly model the in-situ distribution of polymer concentration while accounting for its effects on fluid properties such as increasing water viscosity as a function of polymer concentration and loss of polymer caused by adsorption. Despite advances in numerical techniques and computer hardware, the numerical modeling of polymer floods using Eulerian-based approaches such as finite difference (FD) remains a challenge: Coarse grids tend to excessively smear concentration fronts, masking the true impact of polymers; yet introducing finer grids inevitably leads to excessive run times, making the use of modern reservoir-engineering workflows unrealistic. This problem was already outlined by Lake et al. (1981). We revisit the same problem 30 years later in the context of modern streamline (SL) simulation techniques.We present the extension of modern SL simulation to field-scale polymer flooding, which represents a step change from the hybrid, 2D steady-state models used in the 1970s. We apply well-established physical models for polymer flooding to capture the displacement efficiency in 1D, and couple it with a 3D SL simulator to capture the interpattern sweep efficiency caused by well rates, reservoir architecture, and reservoir heterogeneity. Because modern 3D SL simulators account for changing well rates, nonuniform initial conditions, and gravity, adding polymer functionality means that real-field polymer floods can be modeled efficiently using SLs so as to be useful in modern reservoir-engineering workflows that center on assessing uncertainty and risk associated with design parameters and geological scenarios.In this paper, we proceed to outline the basic architecture of a SL simulator with a polymer option. The physics of polymer flooding is the same as that being used in established FD codes. We discuss advantages and disadvantages of the formulation and present numerical experiments in 1D, 2D, and 3D to illustrate our results.
Debottlenecking and Computational-Fluid-Dynamics Studies of High-and Low-Pressure Production Separators
Authors: Lee Joseph M. , Khan Rafiqul I. , Phelps Daniel W. 
Published: June 2010

Summary
Efficient and effective oil/water/gas separation is required for success of many production operations. A major oil producer was experiencing difficulties with the oil/water/gas separation equipment on an offshore platform and improvements were required to meet both present and future production rates. Both high-pressure (HP) and low-pressure (LP) separators on a major oil production platform were studied to determine the design limitations for foamy service and basic sediment and water (BS&W) levels. Computational-fluid-dynamics (CFD) studies were completed to show the volumetric utilization and flow-pattern improvements made with the design changes.
Both HP and LP separators showed substantial foam and poor efficiency because of poor inlet-device design, plugging, and other general vessel-design limitations. Debottlenecking efforts determined that, while the inlet device was somewhat ineffective, major improvements could be made from changes to perforated plate baffles, fluid-level adjustments, and weir placement and operations.
CFD calculations performed on both vessels indicated similar problems. The perforated plate baffles with improper design lead to countercurrent flow through the baffles, making them less effective in flow control and distribution. Fluid-level settings for the weir height affected the velocity differences between fluid layers and contributed to promotion of recirculation within the vessel, which lead to low volumetric utilization.
With adjustments to vessel internal equipment and changes to fluid-phase levels, CFD calculations showed that overall vessel volumetric utilization was improved by 22% for the HP vessel and by 38% for the LP vessel. CFD results also showed the changes to the flow patterns accompanying these improvements.
Vessels with the proposed changes were operating effectively with substantially higher throughputs and meeting the expected BS&W levels for operations of the downstream oil-processing equipment. Details about the vessel internals, flow properties, and other changes required to accomplish these improvements will be discussed.
Characterization of Reservoir Heterogeneity Through Fluid Movement Monitoring With Deep Electromagnetic and Pressure Measurements
Authors: Zhan Lang , Kuchuk Fikri , Al-Shahri Ali M. , Ma S. Mark , Ramakrishnan T.S.. S. , Altundas Y.B.. B. , Zeybek Murat , Manin Yves , Tartaras Efthimios , Loubens Romain de , Chugunov Nikita 
Published: June 2010

SummaryThis paper presents a novel technique to characterize detailed formation heterogeneity for a carbonate reservoir using measurements from electrode resistivity array (ERA), a wireline formation tester, and a permanent downhole pressure sensor. The ERA was installed on tubing in a barefoot well rather than permanently cemented outside the casing as in previous applications. This notable difference provided flexibility for device installation and operation but also introduced particular issues in the ERA data acquisition and interpretation. Furthermore, the ERA measurements were carried out in conjunction with low-salinity water injection and oil and water production in the same well. The primary finding presented in this paper is that the time-lapse ERA voltages near a source electrode showed unique characteristics that represented local formation heterogeneity. This localized sensitivity of ERA data allows detailed characterization of the formation heterogeneity within the length of the ERA string in the vertical direction and about 100 ft laterally around the wellbore. The scale size of the investigated formation heterogeneity is comparable to typical grid sizes used in current reservoir simulations. Models were developed to identify stratified permeability heterogeneities from the time-lapse ERA voltages. The stratified heterogeneity estimated from the ERA measurements was compared to and verified by openhole logs and core analyses data. The final heterogeneous reservoir model from the ERA was subsequently applied to a numerical simulation that integrated the dynamic fluid flow, salt transport, and electrode array responses for monitoring water-front movement and estimating multiphase formation properties. The history matching of the time-lapse ERA data confirmed the first pass estimates of the identified heterogeneities.
Comparative Proof of Concept Results for Electrothermal Dynamic Stripping Process: Integrating Environmentalism With Bitumen Production
Authors: McGee Bruce C. W. , McDonald Craig W. , Little Les 
Published: June 2010

Summary
The electrothermal dynamic stripping process (ET-DSP™) was commercialized as an environmental remediation technology to remove volatile soil contaminants. After nearly 10 years of use, it has been adapted for the thermal stimulation and recovery of bitumen from oil sand reservoirs. A proof of concept field pilot (McGee 2008) in the McMurray formation was conducted in 2007 and was deemed to be successful. Using a tight well spacing, the pilot demonstrated the effective recovery of approximately 75% of the original bitumen in place. Sand production was minimal, and the produced bitumen was emulsion-free. An expanded field test is currently under way to establish commercial viability of the ET-DSP process as an in-situ recovery process. Validation and calibration of the computer simulation model from the initial pilot test is presented along with details of the expanded field test.
The Athabasca oil sands are well known to the public as open-pit mining or steam-assisted gravity drainage (SAGD) in-situ projects. Approximately two-thirds of the Athabasca oil sands resource base occurs at depths that are defined as either too deep to surface mine or too shallow for currently available in-situ techniques. Furthermore, concerns regarding environmental issues that arise from these methods have the potential to slow their development. The ET-DSP process represents an alternative in-situ recovery technology that delivers significant environmental advantages in addition to its ability to access bitumen reserves that otherwise would not be recoverable. With growing public expectations for reduced greenhouse gas emissions, reduced fresh water usage, and improved management of waste water, as well as the accelerated reclamation of disturbed land and boreal forest, there are many drivers to support the commercial development of the ET-DSP technology.
Compositional and PVT Analysis for Determining Liquid Dropout in Pipelines
Authors: Esmaiel T. E. H. , Al Qallaf A. A. A. 
Published: June 2010

Summary
A lot of equipment is not designed to handle liquids in the operations of a gathering center or gas booster station. In the study area, some compressors were having vibration problems because of amounts of liquid condensate in the flowline caused by sudden changes in pressure and temperature.
The primary objectives of this study are to determine under what pressure and temperature conditions liquids occur and to determine the proper operating conditions. The process involves collecting samples in the field, laboratory analysis, computer equation of state (EOS) modeling of the fluids, and analysis of the phase regions.
Samples were collected at two different locations in the gas line. The samples were sent to the laboratory for compositional and PVT analysis where physical properties were measured. Compositional analysis was performed on the gas and the condensate samples, and liquid dropout tests were performed on the samples.
An EOS simulator was used to characterize the samples and was tuned to match the pressure, volume, and temperature (PVT) data. The tuned simulator was used to perform flash calculations to calculate vapor liquid equilibrium (VLE) for the samples. The simulator was used to develop phase envelopes and physical properties of the gas to determine the amount of liquid dropout at the current operating conditions. These phase envelopes were used to determine new operating conditions to avoid liquid dropout. As anticipated, the primary solution was an increase in the pressure in the line to avoid the two-phase region.
Lagrangian Decomposition of Oil-Production Optimization Applied to the Troll West Oil Rim
Authors: Foss Bjarne , Gunnerud Vidar , Díez Marta Dueñas 
Published: June 2010

Summary
This paper proposes a method based on Lagrangian decomposition for real-time production optimization. It argues the method is well suited for the well-allocation and routing problem in the upstream industries. A semirealistic field case assuming steady-state conditions is used to compare the merits of the method with current industrial practice. The method compares favorably and is therefore an interesting option in real-time production optimization. There are several reasons for this. An error bound on the solution of the production optimization problem can be computed, which is clearly information of interest to any user. Furthermore, the algorithm is efficient and can be parallized for an even higher efficiency. Finally, the Lagrangian decomposition method provides a tool for understanding how a limited resource, such as gas capacity, is used in production optimization.
Kinetics of the Reaction of Citric Acid With Calcite
Authors: Alkhaldi M.H.. H. , Nasr-El-Din H.A.. A. , Sarma H.. 
Published: June 2010

Summary
Previous studies of citric acid/calcite have been limited to coreflood tests and bench-scale experiments. However, the kinetics of a citric acid reaction with calcite has not been measured. This paper gives, for the first time, the kinetics of citric-acid/calcite reaction, which will provide a better way to model the performance of citric acid as a standalone stimulation fluid.
In this paper, the rotating disk apparatus was used to study citric-acid/calcite reaction at a pressure of 1,000 psi, temperatures from 25 to 50°C, citric acid concentrations from 1 to 7.5 wt%, and disk rotational speeds from 100 to 1,000 rev/min. The reaction rate of citric acid with calcite was found to be dependent on the initial citric acid concentration, disk rotational speed, and temperature. For example, at 50°C, the reaction was reaction-rate-limited at rotational speeds greater than 500 rev/min, using high initial citric acid concentrations (3, 5, and 7.5 wt%), while at low acid concentrations (1 and 2 wt%), the reaction was mass-transfer-limited even at high rotational speeds (1,000 rev/min). During the reaction of citric acid with calcite, calcium citrate precipitation occurred at different acid concentrations and rotational speeds. The amount of this precipitation was found to be a function of both the initial citric acid concentration and disk rotational speed. More calcium citrate precipitated at high initial citric acid concentrations, especially at high rotational speeds.
Calcium citrate precipitation occurred at the calcite surface, even at low initial citric acid concentrations. Because of this precipitation, the equilibrium of the citric-acid/calcite reaction was disturbed and the reaction shifted toward the forward reaction (toward the products). Therefore, the overall reaction rate was governed mainly by the rate of the forward reaction, and, hence, it was modeled by a new simplified reaction-rate equation; rate = kf{Ka1·CB}n/2 The average value of the reaction order (n) was found to be 0.833. In addition, the value of the reaction-rate constant (kf)was determined at various temperatures. The effect of temperature on the reaction-rate constant was found to follow the Arrhenius law, where the activation energy was found to be 63.1 kJ/mol.