bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theory And Applications Of The Borehole Audio Tracer Survey
Authors: Britt E.L. 
Published: December 2007

Abstract
The Borehole Audio Tracer Survey (BATS or sound survey) is a new surveying device which can be used to locate and quantify fluid flow outside of casing. Additionally the sound* logger can be utilized as a flowmeter (without moving parts) to measure fluid flowing past the tool.
Part I illustrates use of the BATS log to locate and evaluate the quantity of fluid flow outside of casing. It is demonstrated that an index of flow magnitude can be determined and, as a result, a monetary value can be placed on this lost production.
Part II demonstrates the use of the BATS log to determine the relative flow rate of individual perforations in limited entry completion, where mass flow rate through the perforation is sufficient to produce turbulent flow. An additional technique for evaluating perforated zones (e.g. 4 per ft., etc.) is also shown.
Part III demonstrates use of the BATS device as a downhole flowmeter having no moving parts. It is shown that the BATS device, unlike mechanical flowmeters, can, under favorable circumstances, identify the type of fluid flowing (e.g. liquid, liquid-gas, or foam) as well as the flow rate.

Introduction
Since the Borehole Audio Tracer Survey is a new log to most interpretors, a description of the equipment, logging technique, and a brief theoretical explanation will be given. Additionally, two required corrections to observed log values will be explained.
Equipment - The downhole tool is 1 11/16" in diameter and 48" long with a 15,000 psi and 350 deg. F temperature rating. It can be run in conjunction with a temperature device to provide sequential surveys on a single trip in the hole. A very useful combination is the temperature and sound logger both recorded under shut-in and flowing conditions.
The downhole tool is simply a very sensitive microphone with a downhole amplifier. The transducer is designed to respond to sound which originates in any direction around the well and therefore has no directional properties.
Upgrading Athabasca Tar Sand Using Toe-to-Heel Air Injection
Authors: Xia T. X. , Greaves M. 
Published: December 2007

Abstract
The unique operation of the THAI process – Toe-to-Heel Air Injection, enables very high oil recovery and substantial in-situ upgrading. Both thermal upgrading (non-catalytic) and also catalytic upgrading, in which a catalyst is emplaced along the horizontal producer well, were investigated. 3-D physical model experiments were conducted on virgin Athabasca Tar Sand bitumen to investigate dry and wet combustion performance. These results were compared against those from a steamflood test, which was also followed by air injection. Excellent ignition and very stable combustion propagation was achieved using Athabasca Tar Sand. Thermal upgrading achieved nearly 10 API points increase. Additional upgrading was achieved using an in situ catalyst. The main limitation of using steam is that a very large fraction of the oil remains immobile. This residual oil can only be ‘unlocked’ by thermal cracking at high temperature (&gt;500°C), as in THAI. THAI has the extra advantage that some hydrogen is generated in situ, providing further significant upgrading via hydroconversion. There are also substantial environmental benefits because of the large reductions in sulphur and heavy metals in the produced oil. Furthermore, oil is produced without ‘displacement delay’, immediately ahead of the combustion front. The Oil recovery using THAI was greater than 75% OOIP.
Gel Water Shutoff in Fractured or Faulted Horizontal Wells
Authors: Lane R. H. , Seright R. S. 
Published: December 2007

Abstract
Advancement in design and implementation of polymer gel water shutoff treatments in horizontal wells that penetrate fractures or faults have come from empirical improvements in the field and synergism between monitored field treatments and independent laboratory research. One case history will be detailed, followed by a summary of several other treatments.
Simple calculations can give at least a rudimentary indication of the width of the fracture or fault that causes excess water production. Using laboratory data coupled with field data collected before, during, and after gel injection, the calculations can also give an indication of how far the gel has actually penetrated into the fracture. Our analyses reveal critical measurements that should be made during field applications and where additional laboratory work is needed to aid in the design of field applications.
Development of a Single-Trip Coiled Tubing Sidetracking System
Authors: Grigor C. , Seale R. A. 
Published: December 2007

Abstract
Advancements in sidetracking and re-entry operations have progressed greatly over the past decade. However, these advancements have been predominantly in rotary applications. Milling systems for coiled tubing (CT) operations have evolved much slower. Size limitations have played a major role in the technology transfer from rotary applications. Currently multiple trips are required to successfully complete window milling operations.
Over the last 18 months a single trip CT sidetracking system has been developed that optimizes the efficiencies of the bottom hole assembly and the whipstock in CT sidetracking operations. This paper will discuss the bottom hole assembly analysis used to develop a specialized whipstock and mills for coiled tubing operations with the limited available power from smaller downhole motors.
Results of conventional one trip rotary systems will be compared to the new design in yard testing. These results will be followed by an analysis of each of the first six field trials performed utilizing the new system in vertical and horizontal applications.
An Investigation of ASTM Type I Cement for Oilwell Application in the Appalachian and Michigan Basins
Authors: Myers Roger R. 
Published: December 2007

Abstract
Cement manufacturers in the Appalachian and Michigan Basins stopped making API Class A cement years ago. Today, the pumping service industry provides its customers with Type I cement manufactured to ASTM C150-97 specifications. Many operators in these producing basins are unaware of this change and its implications for a quality cement job.
Much has been written about the characterization of Class H and other oilwell cements. For example, Polkowski concluded that the cement thickening time is directly related to Blaine Fineness and the average size of the C3S crystals and fluid loss control is a function of particle size distribution.1 Nelson traced the variability in oilwell cement back to the production plant, stating portland cement behavior can be linked to several production parameters including kiln temperature, raw materials processing and grinding. 2
It is the intent of this paper to educate the reader about the characteristics of ASTM C150-97 Type I cement being pumped in the Appalachian and Michigan Basins today. Cement from six different cement plants was analyzed using cement microscopy and chemical analysis. Typical cement laboratory tests were run to get a comparison of thickening time, compressive strength development and rheology using normal water/cement ratios.
Effects of Proppant Pack Concentration and Polymer Residue on Appalachian Stimulations
Authors: Mack David J. 
Published: December 2007

Abstract
The purpose of a hydraulic fracturing treatment is to provide a continuous path to the wellbore for hydrocarbon flow. The conductivity of this path has been shown to be effected by many factors including proppant size and physical properties, proppant fracture face concentration, closure pressure on the proppant and proppant pack damage. However, these studies have tended to investigate higher concentrations, typically in the range of 2 lbm/ft2 at closure pressures greater than 1,500 psi and temperatures in excess of 125° F. These criteria are generally outside the conditions experienced in typical Appalachian Basin applications.
This study investigates fracture face proppant concentrations less than 1.25 lbm/ft2, closure pressures less than 1,500 psi and temperatures below 125° F. In addition, the effects of polymer residue (actually polymer recovery) on low concentration proppant packs will be presented. The modified conductivity values are used in a production simulator to show the productivity effects exhibited by polymer residue in low fracture face proppant concentration wells.
Improving Gas Storage Development Planning Through Simulation-Optimization
Authors: Johnson Virginia M. , Ammer James R. , Trick Mona D. 
Published: December 2007

Abstract
This is the first of two papers describing the application of simulator-optimization methods to a natural gas storage field development planning problem. The results presented here illustrate the large gains in cost-effectiveness that can be made by employing the reservoir simulator as the foundation for a wide-ranging search for solutions to management problems. The current paper illustrates the application of these techniques given a deterministic view of the reservoir. A future paper will illustrate adaptations needed to accommodate uncertainties regarding reservoir properties.
Applying High-Resolution Numerical Schemes in Reservoirs Described by Complex Corner-Point Grids
Authors: Sammon Peter H. , Kurihara Masanori , Jialing Liang 
Published: December 2007

Abstract
Higher order numerical schemes are necessary to get good front resolution when modelling reservoirs using practical block sizes. Methods for such schemes presented to date have focussed on situations where the grids are somewhat regular. To be useful, implementations are required that can apply in situations when the gridding is complex, such as when corner point grids are involved that have non-regular cells, grid refinements are used, and when faults exist. This work discusses the implementation of higher order accurate methods in a corner point setting when refinements and faulting are present, and includes a discussion of how to maintain numerical stability. The implementation is carried out in an equation of state-based fully compositional reservoir simulator that uses complex corner point grids with faulting and refinements, thereby making higher order methods available for field scale reservoir modelling.
The numerical schemes use two point flux calculations and can be up to second order accurate in space in smooth regions, the latter being regions where the various component, phase saturation and pressure distributions (and hence phase velocities) are smoothly varying. A Total Variation Diminishing (TVD) flux limiter is required to maintain numerical stability. Such limiters are applied to the inter-cell flows in each component's mass balance equation to control throughput and to ensure overall stability of the resulting numerical scheme. The application of flux limiters also guarantees that the computed properties remain within their physical ranges. TVD limiters must be applied carefully when complex grids are encountered as cells have varying dimensions and can be partially contacted by neighbouring grid cells on several faces. Special consideration needs to be given to how the limiters are to be evaluated in these situations. This usage extends TVD technology beyond what has already been done in reservoir simulation, and makes its use practical for complicated field scale models.
The results of several simulations are demonstrated. In particular, the ability of the techniques to better resolve sharp fronts can be seen. This leads to a more accurate prediction of overall fluid movements, including fluid contamination and mixing, breakthrough timing, and front and/or fluid bank movement in the reservoir. A more precise evaluation of ultimate recovery for the reservoir is obtained, which leads to the opportunity to improve overall recovery.
The techniques described here can greatly enhance the accuracy of compositional reservoir simulation, and it is shown how these capabilities can be brought to the realm of field scale modelling with complex corner point grids.
Prediction of Oil Production With Confidence Intervals
Authors: Glimm James , Hou Shuling , Lee Yoon-ha , Sharp David , Ye Kenny 
Published: December 2007

Abstract
We present a prediction methodology for reservoir oil production rates which assesses uncertainty and yields confidence intervals associated with its prediction. The methodology combines new developments in the traditional areas of upscaling and history matching with a new theory for numerical solution errors and with Bayesian inference. We present recent results of coworkers and ourselves.
History Matching of Three-Phase Flow Production Data
Authors: Li Ruijian , Reynolds A. C. , Oliver D. S. 
Published: December 2007

Abstract
Adjoint equations for three-dimensional, three-phase flow problems are developed and implemented to calculate the sensitivity of production data to permeability fields and well skin factors. Typically, the development of adjoint equations is rather tedious, but the formulation given here makes the development and numerical solution of adjoint equations straightforward. The procedure for calculating sensitivity coefficients is coupled with a fully-implicit finite-difference simulator to develop an automatic history matching procedure. Even if one does not wish to fully automate history matching, sensitivity coefficients are useful for understanding the physics that control three-dimensional multiphase flow and the influence of local reservoir properties on production data. Procedures to estimate the value of particular types of data (pressure, producing gas-oil ratio and water-oil ratio) for reducing the uncertainty in estimates of reservoir properties are applied and discussed.
Applications of Streamline Simulations to Reservoir Studies
Authors: Samier P. , Quettier L. , Thiele M. 
Published: December 2007

Abstract
Computer models of oil reservoirs have become increasingly more complex in order to represent geological reality and its impact on fluid flow. Memory and CPU time limitations by finite difference/volume simulators force a coarser resolution of reservoirs models through upscaling.
Upscaling can lead to significant difficulties in reservoirs studies: (1) while the fine-scale geological model is build from petrophysical, log, and seismic data, its dynamic behaviour is never checked. As a result, a coarse-scale reservoir study can be linked to a fine-scale geological model but the two might be inconsistent in their dynamic behaviour. (2) Conversely, the upscaled model cannot be properly tested since the flow and production behaviour at the fine-scale level is not available. There is no reference solution for guiding important decisions for building a consistent upscaled model. (3) A large number of sector models are required in designing optimal well patterns.
Streamlines simulation is now an attractive alternative to overcome some of these drawbacks since it offers substantial computational efficiency while minimising numerical diffusion and grid orientation effects. It allows the integration of fine-scale geological models into the reservoir engineering workflow.
In this paper, we demonstrate the usefulness and efficiency of a streamline simulator (3DSL5) in the reservoir engineering workflow. We evaluate its speed, memory requirements and scalability using tracer and black oil test data sets on an SGI Origin 2000 (250 MHz MIPS). Our data are based on real fields and range from 200000 to 7 millions cells with cells as small as 30x30x0;5 meters. We examine problems with pre- and post-processing of large data sets and visualising such simulations. Streamlines allowed us to check the validity of a large geological model and to optimise wells patterns with more than 30 producers and injectors. Application of streamlines to the 10th SPE comparative solution project is also discussed.
We demonstrate how streamline-based simulation has matured from a research tool to an industrial application providing real benefits to engineers as a complementary tool to existing conventional simulation technology based on finite volumes.
Reservoir Simulation Applied to Production Operations
Authors: Briens F. , Chua H. T. 
Published: December 2007

Abstract
Reservoir simulation is traditionally used for reservoir management purpose, in an office environment. Reservoir simulation studies have often a long-term scope and require a significant amount of time to reach completion, generally several weeks. Additionally, traditional reservoir simulators require a considerable amount of training to become proficient in their use. Hence, reservoir simulation usually demands a full-time effort. For these reasons, reservoir simulation is a tool that has found little practical application in production operations and it is extremely rare to see it, for instance, being used at the well site. However, this is now changing with the availability of powerful portable computers and appropriate reservoir simulation software, which can make reservoir simulation an effective tool for decision-making in day-to-day production operations. This paper demonstrates with a number of case histories the variety of applications that reservoir simulation can have in a production environment and the added value it can generate.
Semi-Analytical Modeling of the Performance of Intelligent Well Completions
Authors: Valvatne P. H. , Durlofsky L. J. , Aziz K. 
Published: December 2007

AbstractComplex well configurations coupled with intelligent completions offer great potential for the efficient production of oil reservoirs. One application of this technology is the use of surface adjustable downhole chokes. This allows wells to be divided into separate inflow zones, with each zone produced under a different pressure drawdown, but with production commingled. Chokes can be set to provide a more uniform inflow profile, which acts to delay the breakthrough of water and gas. The practical benefits of this technology have been demonstrated in several North Sea installations.Despite the large technical and economic risks associated with these complex wells, little work has been presented on the detailed modeling of their performance. While it is possible to apply existing finite difference reservoir simulators, such models can be time consuming to build and the accuracy of the results depends on the grid and the well model. Here, we apply semi-analytical solution methods (based on Green’s functions), appropriate for modeling the performance of non-conventional wells operating under single phase flow conditions, to these complex well configurations. The approach entails a fully coupled nonlinear formulation that accounts for pressure drops in the annulus, tubing and downhole chokes.Numerical results for a variety of cases are presented. The high degree of accuracy of the semi-analytical approach is first demonstrated through comparison to results from established methods for model problems. Then, using a geostatistical description of a highly heterogeneous fluvial reservoir, we demonstrate how the method can be used to model the performance of wells with intelligent completions. We show how the technique can be applied to determine downhole choke settings that provide optimal inflow profiles.
Use of Parallel Compositional Simulation to Investigate Productivity Improvement Options for a Retrograde-Gas-Condensate Field: A Case Study
Authors: Jutila H. A , Logmo-Ngog A. B. , Sarkar R. , Killough J. E. , Ross F. C. 
Published: December 2007

Abstract
This multi-disciplinary study involved the use of parallel simulation using the same grid size as the geological model. Various production technology options for the remaining wells in a field development were investigated and the benefits of gas cycling were examined. A geological model covering an area of 40 km2 was simulated using two approaches; one using 3 levels of nested LGR's and the other using an areal upscaling, both had nearly the same number of active grid cells. The 12-component Equation-of-State ("EoS") was substituted by 5-component to optimise the run speed of the simulation, 12-component was used for investigating gas cycling. The final engineering model had 320,000 active cells and completed 1.5-year history-matching runs in 1 hr 27 min using 16 parallel 400MHz processors with 1GB RAM each.
Both methods worked well and the history was matched with minor changes to the geological model. The primary match parameters were the relative permeability curves since relative permeabilities from special core analysis at reservoir conditions were not available. Correlations from the literature were used for the original relative permeability curves. These were modified to capture the effects of near-well velocity stripping by ‘straightening’ the curves and moving the end points. Through a combination of local grid refinement (LGR) and relative permeability modifications, the effects of the condensate dropout near wellbore and the transient effects were captured. These effects reduce the wells' productivity by 40% in the first weeks of production.
In the prediction phase the full field model was used to examine, holistically, the effects and interaction of various options chosen by analytical screening. The main solutions compared were high angle (near horizontal) reservoir penetrations and hydraulically fractured wells. Hydraulic fractures were modelled using LGR to capture the behaviour of the condensate in the fractures. The high angle wells were surrounded by LGR. A large number of prediction cases were run, optimising the development scenario using stochastically derived drilling schedules. Considerations of capital allocation led to the final recommendation from the group of optimal solutions.
Physically Based Higher Order Godunov Schemes for Compositional Simulation
Authors: Thiele Marco R. , Edwards Michael G. 
Published: December 2007

Abstract
Previous studies of higher order schemes for compositional reservoir simulation have mainly involved the use of spatially accurate methods. Our compositional computations in IMPES mode with spatially accurate TVD schemes show that for practical time step sizes the method can introduce significant oscillations.
In this paper, a novel scheme is introduced that is higher order in space and time. Higher order values of the variables of the system are derived at cell faces and are constrained to be monotonicity preserving. The compositional flux is then composed from the cell face variables to produce a locally conservative scheme that is Total Variation Diminishing (TVD) for linear advection and is a higher order Godunov scheme in the case of a non-linear conservation law.
Four component (CH4/C3/C6/C16) and six component (C02/CH4/C4/C10/C14/C20) examples are presented that demonstrate the behavior of the new scheme for complex compositional simulation. The new scheme produces high resolution results at a fraction of the cost of single point upstream (SPU) weighting. One-dimensional computations show that 1000 grid blocks are sufficient for the higher order scheme to approximate 20,000 single-point upstream (SPU) reference solutions leading to significant speed-ups. Our new method permits larger time steps than TVD schemes that are only spatially accurate and is consequently more robust and less CPU intensive than a spatially accurate scheme.