bluuebunny/crossref_metadata_2025_split huggingface dataset:
Horizontal Wells in Tight Gas Sands—A Methodology for Risk Management to Maximize Success
Authors: Baihly Jason , Grant Dee , Fan Li , Bodwadkar Suhas 
Published: December 2007

Abstract
In general, successful applications of horizontal wells have been limited to high permeability reservoirs and unconventional formations such as coal, chalk, and shale. Conversely, few tight gas sandstone reservoirs that require stimulation have realized sustained success with horizontal completions. One example of such success is the Cleveland Sand of North Texas and Oklahoma Panhandle region. Very recently, some success with horizontals has been observed in the Bossier and Cotton Valley Sands of East Texas and North Louisiana. Horizontal wells are commonly two to four times more expensive to drill and complete than offset vertical wells, yet are theoretically capable of up to three to five times the production. Higher gas prices have lead to potentially better economics for horizontal wells. However, research shows that in practice, many of these wells typically produce only 10 to 30% more than offset vertical wells. With costs more than double those of vertical wells, the economics are obviously unfavorable.
This paper discusses ways to identify and manage risks when planning, drilling, and completing horizontal wells in tight sandstone formations in order to improve success.
Evidence has shown that shortcuts and blanket approaches usually do not work in these completion environments. A multitude of lithological and depletion possibilities exist as risks which need to be identified and managed through appropriate application of integrated drilling and completion technologies. Each risk may require different drilling and completion considerations to succeed. There is simply no magic recipe for repeat success.
A detailed methodology is presented to identify, understand, and manage risk associated with horizontal wells drilled in tight gas sandstone reservoirs. The methodology will address all of the complex subjects that need to be considered for the successful placement and completion of a horizontal well including reservoir description (both static and dynamic), well design, drilling, stimulation, and production. It will also illustrate consequences of what may happen if these issues are not properly considered. Through this methodology horizontal well feasibility and economic results can be determined. If a horizontal well has been determined to be economically viable, this methodology can consistently provide a solution as to what the best completion type (vertical or horizontal) is to recover reserves and enhance recovery efficiency in tight gas sandstone reservoirs.
Optimizing the Completion of a Multilayer Cotton Valley Sand Using Hydraulic-Fracture Monitoring and Integrated Engineering
Authors: Baihly Jason , Coolidge Andrew , Dutcher Steven , Villarreal Ruben , Craven Mike , Brook Keith , Le Calvez Joël H. 
Published: December 2007

AbstractMicroseismic hydraulic fracture monitoring is having a major impact in how wells are being completed in tight sand reservoirs. This existing technology is being utilized in new and innovative ways to provide operators a clearer picture of the fracture development. This information can be combined with other fracture diagnostic techniques, and along with sound engineering practices, can have a profound impact on how wells are completed.This paper discusses the completion design methodology, execution, and results from two offset wells. The first well was completed with a two stage hydraulic fracture treatment while the successive offset was completed via a single-stage fracture treatment. The evaluation tools utilized to determine the resultant fracture attributes include microseismic hydraulic fracture monitoring, hydraulic fracture surface treating pressure-history matching, and tracer and production log interpretation in addition to production analysis. The results from each well are compared and contrasted, and a plan for potential future completions is discussed.The microseismic event growth and fracture treating pressures over time revealed how the fracture propagated. In the first well the microseismic and treating pressure results of the first stage showed height growth into the proposed zone to be targeted by the second stage treatment. Lessons learned from the first subject well were then incorporated into the completion design of the offset well to optimize its overall completion efficiency. The second well was hydraulically fracture stimulated with a single stage treatment. The completion design changes incorporated in the second well showed some positive effects on the microseismic fracture geometry and resultant production.An integrated analysis approach can provide an improved understanding of the fracture behavior within a field. This improved knowledge of the fracture system can lead to optimum completion designs and well spacing. These changes can then themselves be evaluated with the aforementioned tools to determine their level of success. This continuous improvement process can be repeated for future fieldwide well completion designs in order to achieve an optimum fracture system within the targeted intervals.
Characterization and Preservation of Karst Networks in the Carbonate Reservoir Modeling
Authors: Shen Feng , Qi Lixin , Han Gehua 
Published: December 2007

AbstractKarstification was developed in the Ordovician carbonate reservoirs resulted from the action of meteoric waters during subaerial exposure. Poor core recovery and borehole imaging logs in permeable sections of the Ordovician carbonate reservoirs lead to poor understanding on karst networks. Due to the complex in geometry and lateral variability in thickness, features of karst networks cannot be clearly explained on 3D seismic. A new integrated approach is proposed, which consists of integrating 3D specially processed seismic geometric attributes, lithofacies and well log and drilling data into imaging karst networks and characterizing their effective properties. Geometric attributes, describing reservoir coherence, dip and lineaments, are seismic frequency dependent and allow reservoir architectures and karst features such as channels, dissolution fractures and sink holes to be identified in different frequency scales. The model-based classification technique is used to describe karst full geometry with estimated geometric attributes. The interpreted karst features are verified with total drilling losses encountered in drilled wells. To incorporate karst network geometries into a deterministic reservoir model, other reservoir heterogeneities based on their effects on reservoir connectivity and permeability are identified. The detailed reservoir architecture mapping for each layer related to karst connectivity and flow heterogeneity is the basis for the modeling carbonate reservoirs. Lithofacies units are characterized by reconciling lithology related attribute data at seismic and well log scales. Reservoir dynamic data are also used to quantify the karst network properties in terms of size, trend and pattern of permeability. With the case study, we demonstrate the application of our new integrated approach to the characterization and modeling of karst networks in the Ordovician carbonate reservoirs. Our results show that quantitative integrated interpretation of karst networks and reservoir architectures can provide a new understanding of carbonate reservoir modeling and underlying geological controls.
Independence Project Completion Campaign: Executing the Plan
Authors: Burman J. W. (Jack) , Kelly G. F. , Renfro K. D. , Shipper D. W. 
Published: December 2007

Abstract
The Independence Project is a world-class subsea tieback development of 10 natural gas fields in the ultra-deepwater of the Gulf of Mexico. Anadarko is presently the operator of eight of the fields, in which 12 wells were pre-drilled to develop the resources. Completion operations began in early 2006 and were finished in early 2007, during which seven single-zone wells, three two-zone intelligent wells, and two three-zone intelligent wells were completed and flow tested from the Transocean Deepwater Millennium drillship.
This paper will document an overview of the Anadarko 10- well completion campaign, during which numerous water depth and completion time records were set, utilizing innovative procedures and downhole designs to safely complete the project significantly ahead of schedule. Rig and BOP modifications, teamwork, effective communication, and novel solutions that positively impacted program effectiveness will be discussed.
Preventing Environmentally Induced Corrosion Cracking by Removal of Thiocyanates from Completion Brines
Authors: Horton Robert L. , Arvie Morris A. 
Published: December 2007

Abstract
While thiocyanates are useful corrosion inhibitors in some low-to-medium temperature ranges, at temperatures of 350°F and upwards, thiocyanates are believed to be prone to thermal decomposition and subsequent environmentally induced corrosion cracking of tubular goods, especially of high strength corrosion-resistant alloys. Stress corrosion cracking has also been postulated to be a risk as a result of hydrogen sulfide production from the decomposition of thiocyanates.
In the life cycle of completion brines, a stock brine is custom-blended with a variety of additives depending on the particular application. In the field, additional components may be introduced, sometimes as contaminants. Once used, completion fluid that is returned to the surface may optionally be subjected to reclamation processes for reuse in a subsequent application. Current API recommended practices specify the testing for such components as solids, pH, and iron; however, it seems reasonable that in the future the recommended practices will also include a specification on the maximum allowable thiocyanate content.
Reclamation processes to date have not focused on the removal of thiocyanates from brines. This paper discusses the laboratory development and field implementation of processes for complete removal of thiocyanates from completion brines before any attempt is made to reuse them. This process works for a wide range of brines, is quite cost-effective, and enables buy-back of used completion brines with only a reasonable additional cost for thiocyanate removal.
Mechanisms and Performance Demonstration of the Gas-Assisted Gravity-Drainage Process Using Visual Models
Authors: Mahmoud T. N. , Rao D. N. 
Published: December 2007

Abstract
The Gas Assisted Gravity Drainage (GAGD) process, developed at LSU, is designed to take advantage of gravity to allow vertical segregation between the injected CO2 and reservoir crude oil due to the difference in their densities. The GAGD process uses the existing vertical wells for CO2 gas injection, and a horizontal well near the bottom of the payzone for oil production.
In this experimental study, a physical model, consisting of two parallel glass plates confining a sandpack, has been used to visually discern the mechanisms operative in the GAGD process. The model was also designed to adopt different vertical well configurations. The model experiments have shown that GAGD is a viable process for secondary and tertiary oil recovery. Oil recovery in the immiscible secondary mode was as high as 83% IOIP and the oil recovery in the immiscible tertiary mode was 54% ROIP. The model has also shown that the gas injection depth may not have an influence on oil recovery as long as there is vertical communication between reservoir layers. The visual model experiments have also demonstrated that GAGD is also applicable in naturally fractured reservoirs. The visual model showed near perfect microscopic sweep efficiency for the miscible GAGD process performed using model fluids.
This paper presents the results of these visual model experiments of the new GAGD process and the various mechanisms responsible for high oil recoveries including Darcy-type displacement until gas breakthrough, gravity drainage after breakthrough, and film drainage in the gas invaded regions.
Effect of Methane on the Global Climate Change
Authors: Bin Dou , Guosheng Jiang , Xiang Wu 
Published: December 2007

Abstract
Methane (CH4) is the most abundant organic compound in the Earth's atmosphere, where it acts as a greenhouse gas and thus has implications for global climate change. In order to completely understand the effect of methane hydrate melting on the global climate change, we present a theoretical study of the climate response to a massive release of methane from methane hydrates. The results showed that the total contribution to the atmosphere from geologicall sources is estimated to be 45Tg CH4 per year, which would result in a further rise in global temperature to induce the destabilization of hydrates. So the destabilization of gas hydrates is likely to be serious hazards in the near future due to the effects of global warming.
Extended Analysis for Gas Condensate Systems
Authors: Hosein Raffie , McCain William D. 
Published: December 2007

Abstract
Equation of State (EOS) predictions for gas condensate systems require extended analysis beyond the heptanes plus fraction. In the absence of experimental data, several schemes have been proposed to extend these compositional data based on the observation that a single straight line relationship exists between log of mole percent and molecular weight for these pseudo-components or Single Carbon Number (SCN) fractions.
An examination of compositional analysis for gas condensate systems showed a discontinuity in the relationship between mole percent and molecular weight at C13. As a result two straight lines are needed for a more accurate description of mole percent; one from C8 to C12 and the other from C13 and beyond. An average absolute deviation of less than 6.0 % between the predicted and experimental mole percent was obtained using parameters from two straight lines. From a single straight line relationship this difference was as high as 36.0 %.
When applied this new universal observation gives an improved prediction of the mole percent of the last fraction. As a result a more accurate description of molecular weight for this fraction can be achieved for use in equation of state predictions. The change in slope at C13 indicates that for gas condensate systems a partial analysis is required up to C12 and splitting schemes can be applied from C13+ and beyond using a single straight line relationship. Beyond C12, experimental data shows that the mole percent of the isomers present are too small to cause any further change in slope.
The Cost of Errors in Estimates Used in Concept Selection
Authors: Jablonowski Christopher J. , Wiboonkij-Arphakul Chaiyaporn , Neuhold Mark Darren 
Published: December 2007

Abstract
This study examines the loss in project value incurred when concept selection decisions are based on erred estimates of input variables. Estimates of the magnitude of such losses are provided, along with an analysis of which input estimates matter most in determining value loss. A procedure for concept selection is defined to model the decision making process and is used in conjunction with a simplified asset development optimization model to estimate project values. The analysis compares project values resulting from concept selection decisions based on erred estimates and decisions based on an alternate hypothesis. Results suggest that cost of erred estimates for initial costs, expansion costs, and the timing of future expansion projects are comparable in magnitude to the cost of erred reserve estimates. Also, the cost of underestimating expected reserve volume tends to be larger than the cost of overestimating reserve volume; aggressive cost estimates are more destructive to value than conservative estimates; and conservative schedule estimates for the timing of expansion projects are generally more destructive to value than aggressive schedule estimates.
A New Thermal Compositional Reservoir Simulator with a Novel "Equation Line-Up" Method
Authors: Huang C. K. , Yang Y. K. , Deo M. D. 
Published: December 2007

Abstract
In a thermal-compositional reservoir simulator, pressures, saturations, temperature and compositions in all the existing phases must be solved. When this equation system is solved implicitly, a system of nonlinear equations results, which is solved by the Newton's method. This requires computation of the Jacobian matrix of partial derivatives. If the appropriate dependent variable is not lined-up with the correct equation, zero pivot elements are generated in the Jacobian matrix. This situation is complicated by the fact that new phases may appear, and existing phases may disappear leading to the type and number of dependent variables changing constantly. Elimination of these zero pivot elements using pivoting is computationally expensive for large matrix systems. In this paper, we present a robust algorithm for lining-up the dependent variables and the equation system appropriately to avoid zero pivots in the Jacobian.
This technique can be applied to the thermal-compositional model with any number of components and phases and there is no constraint on the number of thermal equilibrium relationships. In a system with Nc components and Np phases, and Ne thermal equilibrium constraints, Nc+Np+Ne+2 dependent variables are lined with appropriate equations (pressure and temperature are the two additional variables). Any phase equilibrium calculation (K-value based, equation of state) can be used in this approach.
The motivation for equation line-up and some previous methods are presented followed by a description of the conservation and constraint equations in thermal modeling. A brief description of the simulator framework that allows coupling different physical models and discretization methods is provided. The rules of variable selection for avoiding zero pivots are discussed in detail, including a method to obtain analytical derivatives. As proof of concept, two applications are discussed: a steamflooding example in a fractured system, using the discrete-fracure modeling approach and in situ combustion. A control volume finite-element discretization is used in steamflooding while a finite-difference approach based on the Cartesian grid is employed in the in situ combustion application.
Identification and Classification of New Three-Phase Gas/Oil/Water Flow Patterns
Authors: Keskin Cengizhan , Zhang Hong-Quan , Sarica Cem 
Published: December 2007

Abstract
Three-phase gas-oil-water experiments have been conducted in horizontal pipes at various flow rates and water cuts. Three-phase flow patterns have been observed and identified using a high speed video system and a new classification of three-phase flow patterns is proposed. Twelve new three-phase gas-oil-water flow patterns are: Stratified-Stratified, Stratified-Dual Continuous, Stratified-Oil Continuous, Stratified-Water Continuous, Intermittent-Stratified, Intermittent-Dual Continuous, Intermittent-Oil Continuous, Intermittent-Water Continuous, Annular-Oil Continuous, Annular-Water Continuous, Dispersed Bubble-Oil Continuous and Dispersed Bubble-Water Continuous. The flow pattern maps are presented based on the new three-phase flow pattern classification. Comparisons made with the available two-phase flow pattern model predictions show the inadequacy of the two-phase flow models in characterization of three-phase flow.
Overview of Beam Pump Operations
Authors: Rowlan O. Lynn , Lea James F. , McCoy James N. 
Published: December 2007

Abstract
Beam pumping systems are the most commonly applied worldwide artificial lift method with 59% of all Artificial Lift in North America and 71% of 832000 wells for the rest of the world (World Oil 2000). This paper reviews many of the concerns that operators face when using the sucker rod pumping system. Operational concerns are introduced with a review of the advantages/disadvantages of the system. Automation and Pump-off Control (POC) are discussed. The most commonly automated operating parameters are examined and the technique of configuring POC set points is llustrated. To maintain efficient operation requires that pumping should be done only when the pump has a high percent of liquid fillage. Methodology for designing how to efficiently produce the well by selecting pumping speeds, stroke lengths and plunger diameters is reviewed.
Incomplete pump fillage, tagging on the downstroke, and other downhole conditions contribute to rod buckling and subsequent accelerated rod/tubing wear and possible other damage. Commonly applied solutions such are weight bars and rod guides are reviewed. Dynamometer cards, particularly calculated downhole pump cards are used for diagnostics of problems that exist in a well.
Finally simple best practices are reviewed covering POC's, use of predictive design programs, guidelines for sucker rod applications, downhole pump best practices, surface unit best practices, tubing, gas separation, use of fluid level instruments (fluid shots), effects of casing pressure, and finally some mention of solution to corrosion problems. The paper reviews older practice and suggests newer practice to assist the operator with operational concerns. In general, sucker-rod pumping is the premier method of artificial lift. Many operators will use some other lift method only after justifying why not to use beam lift.
Barriers to Implementation of Real-Time Optimization Technology
Authors: Hite J. Roger , Crawley Charles , Deaton David F. , Farid Kemal , Sternesky Michael 
Published: December 2007

Abstract
The SPE Real Time Optimization Technical Interest Group conducted a survey of its members earlier this year to learn more about the barriers to implementation of this technology. Understanding the barriers better will allow us to focus on the more important issues.
The survey was in two parts. The first asked about the overall process of getting from data to decisions and action. The second focused on the usage of technical and business tools.
This paper summarizes the results of the survey. We found that each step in the process has considerable major and minor barriers to overcome. The most difficult steps were in the areas of business analysis, recommendations / decisions and taking action. These are areas where management can have the greatest impact through improved work processes, governance and procedures. The results also show there is considerable need for improved commercial technical and business analysis tools