bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macrokinetics of Matrix Gas Release and its Influence on Coalbed Methane Flow and Production
Authors: Fathi E. , Akkutlu I. Yucel 
Published: May 2009

Abstract
In coalbeds and shales, gas transport and storage are important for accurate prediction of production rates and for the consideration of subsurface greenhouse gas sequestration. They involve coupled fluid phenomena in porous medium including viscous flow, diffusive transport and adsorption. Standard approach to describe gas-matrix interactions is deterministic and neglects the effects of local spatial heterogeneities in porosity and material content of the matrix. In this work, adopting weak-noise and mean-field approximations and using a statistical approach in spectral domain, matrix heterogeneity effects are investigated in the presence of non-equilibrium adsorption with random partition coefficient. It is found that the local heterogeneities can generate non-trivial transport and kinetics effects which retard gas release from the matrix and influence the ultimate gas recovery adversely. Macro-transport shows 1/ [1 + NPe / (1+ NPe)] dependence on the Péclet number, and persists at the diffusive ultra-low permeability limit. Macro-kinetics is directly related to Thiele modulus by the following expression: NTh / (1+2 NPe). It leads to trapping of gas in the adsorbed phase during its release from the matrix and to an adsorption threshold during the gas uptake by the matrix. Both effects are proportional to the initially available adsorbed gas amount and become more pronounced with the increasing variance of the porosity field. Consequently, a new upscaled deterministic gas mass balance is proposed for practical purposes. Numerical results are presented showing free and adsorbed gas distributions and fractional gas sorption curves for unipore coal matrix exhibiting Gaussian porosity distribution. The work is a unique approach for our further understanding of the coalbeds and gas shales, and it is important for the development of sound numerical gas production and sequestration models.
New Fracturing Fluid for High Temperature Reservoirs
Authors: Abad C. , Mirakyan A. , Parris M. , Chen Y. , Mueller F. 
Published: May 2009

Abstract
The extent of crosslinking a polymeric fracturing gel can significantly contribute to the success or failure of a hydraulic fracturing treatment. In certain cases, excessive crosslinking while the fluid is in the tubulars can result in friction pressures that are too high, and may prohibit the treatment from achieving the design goals. With titanium (Ti) or zirconium (Zr) crosslinked gels, which are known to be prone to irreversible shear degradation, early crosslinking in the tubulars can substantially reduce the final gel strength, even to the degree that near wellbore proppant transport is compromised, and the treatment may screenout. On the other hand, a Ti or Zr crosslinked gel which crosslinks substantially after exiting the perforations may not have sufficient proppant transport capability to complete the treatment successfully.
Varying treatment conditions such as mixwater composition and temperature, tubular shear rate and transit time, and reservoir temperature pose difficult challenges to routinely achieving the optimal crosslinking state. Conditions such as offshore wellbore temperature profiles and viscous heating in smaller diameter tubing can further complicate the task. Various chemical means have been employed to tune the crosslinking temperature for specific treating conditions. These methods involve addition of chemicals to control the crosslinking kinetics, such as pH buffers, crosslinker concentration, and competing ligands to temporarily bind the metal crosslinker. Blended crosslinkers containing a single Group 4 (Ti, Zr) metal with different organic ligands with different binding strengths have been employed to achieve crosslinking at two temperature ranges so that early viscosity for proppant transport can be developed. Mixed metal crosslinkers, such as aluminum and Zr have also been formulated for this same purpose.
This paper examines the disadvantages of these strategies, and describes the development and deployment of a high-temperature fracturing fluid system that has shown to overcome those issues.
Laboratory Evaluation of RPM for Profile Modification in Injection Wells
Authors: Vasquez Julio , Eoff Larry , Dalrymple Dwyann 
Published: May 2009

Abstract
In the absence of profile modification, water injected into the reservoir will go into the high-permeability zones and will bypass the oil-saturated, low-permeability zones. This paper presents the laboratory evaluation of a water-soluble relative permeability modifier (RPM), a hydrophobically modified polymer that was developed initially for water control in production wells. By injecting the RPM within the high-permeability zones, injected water will be diverted into low-permeability zones to improve the sweep efficiency of the waterflooding project.
The polymer functions by adsorption onto rock surfaces and effectively reduces water flow with little or no damage to hydrocarbon flow. The treatments are extremely easy to mix and pump and require no postjob shut-in time. This RPM was evaluated in 5-ft and 10-ft sandpacks to investigate the following parameters: (a) depth of penetration, (b) diversion properties (c) injection rate, and (d) polymer concentration. High-permeability (~2000-1500 mD) and low-permeability (~250-150 mD) sandpacks were evaluated as porous media. Based on this laboratory evaluation, this RPM can effectively penetrate through a 10-ft sandpack providing permeability reduction to water throughout the length of the porous media. In addition, excellent diverting properties were observed while bullheading the treatment in sandpacks in parallel with significant permeability contrast.
Application of a Design Customization Process Provides Immediate Solution to Microtortuosity Issues in Known Field
Authors: Sieyra J. , Lundin S. , Medina G. , Cortina C. 
Published: May 2009

Abstract
When wellbore micro-tortuosity in Neuquina Basin wells in Argentina made logging information unreliable or difficult to acquire, a collaborative process was initiated between personnel from drilling engineering and from the bit application design group. This collaboration resulted in a custom PDC bit solution that reduced vibration and improved overall wellbore quality without sacrificing steerability or penetration rate.
In the El Trapial field, drilling practices over the course of more than 800 wells have progressed from use of roller cones bits to rotary drilling using PDC bits. Additional improvements were realized with the addition of mud motors that achieved better rates of penetration. The use of various bit types to finely-tuned design configurations have now resulted in record rates of penetration (ROPs).
As the performance improved, additional directional targets have been incorporated into the operation, making the wells slightly more complex, but still manageable. However, increased wellbore tortuosity has made the acquisition of logging data difficult and the acquired data questionable. Specifically, the reservoir department expressed concern about the accuracy of the acquired data, and consequently some calculations of saturations (Sw) were questioned.
This paper describes the process used to determine the bit design parameters needed to optimize performance and to improve the wellbore quality in these wells. The process required gathering, compiling, and processing extensive data on all aspects of drilling. The anticipation of improved performance was based on a review of previous bit design features, historical developments in bit design, dull condition studies, studies of penetration rate vs. drilling parameters, formation statistics and field feedback, directional survey data, specific energy studies, and reported performances improvements. This paper also describes the collaborative design process, the resulting changes in bit design, and the performance results.
Integrated Production Model With Stochastic Simulation to Define Teotleco Exploitation Plan
Authors: Czwienzek F. B. , Perez J. Barreto , Salve J. G. , Martinez Ramirez I. , Gerardo M. V. , Aguilar R. H. 
Published: May 2009

Abstract
PEMEX Exploration & Production, with the technical support of Landmark Halliburton Mexico, implemented front-end-loading (FEL) methodology to define the optimum exploitation plan for the Teotleco oil field. FEL methodology, a relatively new approach in upstream project evaluation, considers the generation of multiple scenarios and analyzes the uncertainty and risk associated with each scenario.
A decision matrix was used to generate the scenarios in which several exploitation options were considered. One scenario was the current base case. Traditionally, base cases have been documented in a deterministic way using mathematical models, supported by exponential decline curves, for calculating production forecasts without considering the effects of individual wells and surface facilities. At the present time, however, there is commercial software that considers not only reservoir and well conditions but also considers surface operational conditions for production forecasts. This software leads to more realistic results.
Integrated Production Models(IPM) are very useful tools for calculating production forecasts and for optimizing field development. These models only provide a single possible solution each time they are run; but, now, deterministic models can be coupled with stochastic simulation programs to obtain probabilistic results.
Stochastic models require that uncertainties associated with each variable in the value chain (reservoir, drilling, productivity, facilities, economic evaluation, safety and environmental protection) be identified, characterized, and included in a new model, the Fully Integrated and Stochastic Asset Model (FISAM).
This paper shows the workflow to integrate reservoir (material balance), well (nodal analysis), and surface facilities conditions (pipelines and separation conditions), with an economics model (key performance indicators) using a stochastic simulator. The results of this workflow — which consist of production profiles, economic evaluation, and risk analysis — enable managers to improve project decisions.
The Teotleco FISAM model evaluated 15 exploitation scenarios. Review of the Net Present Value (NPV) and the associated risks in the value chain identified and then prioritized those scenarios that challenged the current base case. The flexibility and versatility offered by this approach for evaluating multiple scenarios facilitated the preparation of new updated PEMEX E&P exploitation plans. In these plans, which include new fields such as the Teotleco Field, the level of existing uncertainty will be recharacterized using new information generated as fields are exploited.
High-Temperature Water Control With an Organically Crosslinked Polymer-Case Histories From Mexico
Authors: Mercado M. , Acuna J. C. , Najera D. , Caballero C. , Soriano E. Duverney 
Published: May 2009

Abstract
One of the major challenges faced in southern Mexico is water management. Producing zones are often considered for abandonment even when the intervals still retain large volumes of recoverable hydrocarbons. For many years, conformance-polymer systems have been successfully applied to control undesired water production from hydrocarbon wells. However, currently available polymers present a number of limitations for high-temperature wells (&gt;250°F) in terms of providing longer gelation times and acceptable thermal stability. In most of the wells in Mexico, bottomhole temperatures are above 300°F with depths around 15,000 ft. This paper presents the successful field implementation of an organically crosslinked polymer (OCP) for high-temperature applications in areas of southern Mexico that are producing hydrocarbons from naturally fractured carbonates. These treatments were performed by bullheading through the producing tubing without the need to pull the tubing out of the well.
The OCP system is based on a copolymer of acrylamide and t-butyl acrylate (PAtBA) crosslinked with polyethyleneimine (PEI). To date, about 300 jobs have been performed with the OCP system around the world to address conformance problems such as: water coning/cresting, high-permeability streaks, gravel-pack isolation, fracture shut off, and/or casing-leak repair. More than 150 of these jobs have been performed in Mexico alone. Originally, the OCP system had a limited working temperature range of 100 to 250°F. The upper-placement temperature of the system was ~250°F because above this, temperature-pumping times were too short. A recently developed polyamino-acid retarder has allowed reasonable placement times up to 350°F without the need for cooling down the formation to obtain enough pumping time. The retarder is not detrimental to the thermal stability of the system.
Study of Gas Injection Effects on Rock and Fluid of a Gas Condensate Reservoir during Underground Gas Storage Process
Authors: Moradi B. 
Published: May 2009

Abstract
Underground gas storage (UGS) is a common activity in countries with major transport and distribution gas pipeline infrastructures, which allows to efficiently resolving demand seasonality problems. Natural gas injection and storage in depleted gas condensate reservoirs is a common challenge in downstream petroleum industrial jobs. Generally the gas condensate depletion process take places partially, hence the injected light natural gas into the proportionally heavier condensates lead to remarkable changes in gas relative permeability and condensate saturation. These variations affect gas production directly.
In this work, UGS was studied on a gas reservoir through compositional simulator. The oil field under study is a gas condensate reservoir located in central Iran. A synthetic model of the gas condensate reservoir was generated which investigates the effect of natural gas injection and production upon variations in gas relative permeability and condensate saturation within near and far away areas of the wellbore. Before natural gas injection and production cycles begin to implement, storage able gas volume and base gas in place volume are calculated through volumetric and material balance methods to determine the optimum pressure for the first injection.
It was found that both condensate saturation and gas relative permeability were sensitive to injection rate. The results on gas relative permeability suggest that gas productivity curtailed by condensate drop out can be somewhat restored by increasing injection and production cycles.
Injection of higher volumes of gas in the first cycle prevents condensate from forming and increases gas productivity index.
Drilling Cost Reduction Through Use of Torque Controlling Features on Steerable Drill Bits Within Latin America
Authors: Barton S. , Garcia A. , Pogliano P. , Silva A. , Pelligra M. 
Published: May 2009

Abstract
Toolface Control is widely regarded as one of the greatest challenges when drilling directionally with a Fixed Cutter (FC) drill bit on a Steerable Motor assembly. Toolface offset is proportional to the torque generated by the bit, and by nature, FC bits generate high levels of torque. If large changes in downhole torque are produced while drilling, this will cause rotation of the drill string, and loss of toolface orientation. This results in inefficient drilling and increases risk of bit and downhole tool damage.
This paper examines the effect of varied components of a FC drill bit to determine the key design requirements to deliver a smooth torque response and improved directional performance. This includes review of the results from comprehensive laboratory testing to determine the effectiveness of a number of varied, removable Torque Controlling Components (TCC). These, in combination with specific cutting structure layouts, combine to provide predictable torque response while optimized for high rates of penetration. In addition, unique gauge geometry is disclosed that was engineered to reduce drag and deliver improved borehole quality. This gauge design produces less torque when sliding and beneficial gauge pad interaction with the borehole when in rotating mode.
Field performance studies from within Latin America clearly demonstrate that matching TCC, an optimized cutting structure, and gauge geometry to a steerable assembly delivers smooth torque response and improved directional control. Benefits with regard to improved stability are also discussed.
Successful application has resulted in significant time and cost savings to the operator, demonstrating that Stability and Steerability does not have to result in loss of penetration rate.
Analytical Simulation of the Injection/Production System of La Cira East and North Areas Using CGM Method
Authors: Gomez Vicente , Gomez Adriana , Duran Javier 
Published: May 2009

Abstract
Ecopetrol and OXY signed in september 2005 a commercial and technical agreement to increase the oil and gas production in La Cira - Infantas, a mature oilfield located in the Magdalena Middle Valley basin in Colombia, which was discovered in 1918.
The East and North areas of La Cira - Infantas field had in 2006, 107 producers and 21 injectors active wells and has been waterflooded since 1957. This paper illustrate the methodology used and the results obtained in the estimation of the areal and vertical efficiencies of the waterflooding process using the analytical method of Craig, Geffen and Morsen applied by the use of a software developed by Ecopetrol S.A called ASIA (Advanced System for Injection Analysis).
Available information analysis, databases generation, pattern definition, and history matching were the main considerations applied to implement the methodology which let us to identify non irrupted sands, non swept zones, water losses, existing pattern real status and real performance of the waterflood process in the selected area.
Analytical simulation results showed that the system had serious problems related to lack of hydraulic connectivity between producers and injectors sands and water that had been pumped out of interest zones which were related to zones near to a faulty area. Calculations obtained using the ASIA software, showed that only 233 millions of barrels had been effectively injected in the area, it does mean that nearly 38% of the injected water had been lost.
After this evaluation, Ecopetrol and OXY began an aggressive program of activation of producing wells and injectors and configuring new patterns of injection, a strategy that has led to increase the production of the area in about 3000 bopd.
The application of this methodology using the ASIA software will help in designing and surveillance of waterflooding process in other Colombia fields. Prior knowledge of waterflooding conditions will help in defining better strategies and conditions for the process.
Experimental Design: Three Contrasting Projects
Authors: Murtha J. A. , Osorio R. , Perez H. H. , Kramer D. L. , Skinner R. J. , Williams C. A. 
Published: May 2009

Abstract
The objective of Experimental Design (ED) is to develop one or more proxy equations to represent a reservoir simulator model and then use that equation for Monte Carlo (MC) simulation. A proxy equation is generally a quadratic
(1) Y = a 0 + a 1 X 1 + a 2 X 2 + … + a n X n + b 1 X 1 2 + b 2 X 2 2 + … + b n X n 2 + c 1 X 1 X 2 + c 2 X 1 X 3 + …
which sometimes reduces to linear with no Xi2 or XiXj terms. Here Y represents a reservoir simulator output of major interest such as expected ultimate recovery (EUR) oil or gas. The Xis are initialization parameters for the simulator. These variables are inherently uncertain, such as gas-water contact, pore volume or its components, permeabilities, or trapped gas saturation. The ultimate deliverables of ED are a probability distribution for Y and a sensitivity chart ranking the Xis. The obvious advantage of a proxy equation is that it can be executed in microseconds while the simulator requires hours or even days. The shortcoming is that a proxy equation cannot completely represent the complexities of the simulator. We propose to contrast and compare three recent Colombian ED studies, ranging from an exploration project to a mature field; from two parameters to 10; from 13 years of production history to a single well test; both linear and quadratic proxy equations, and a variety of choices for Y.
Each project offered new challenges and required some departure from a traditional workflow. These mini case studies illustrate the breadth of ED and some pitfalls we encountered. Aside from the simulator and Excel, the only software packages used were generic Monte Carlo and statistical packages.
Any ED project begins by identifying uncertain initialization parameters and ends with a proxy equation and its Monte Carlo simulation. What happens in between, however, depends on the particular situation. The nature of the key output(s), the number of variables, the complexity of the reservoir simulator, the challenge of any history match, and the quality of the results can vary considerably from one project to another. With a methodology relatively new to our industry, sharing the strengths and weaknesses of the process can be valuable.
Laboratory Investigation of E-Beam Heavy Oil Upgrading
Authors: Yang D. , Kim J. , Silva P. C. F. , Barrufet M. A. , Moreira R. , Sosa J. M. 
Published: May 2009

Abstract
Electron beam (E-Beam) heavy oil upgrading, which uses unique features of electron beam irradiation, can be a solution to minimize the critical problem of upgrading heavy oil. Enormous amounts of heavy oil reserves exist in the world, but the lack of cost-effective technologies hinders the development of heavy oil reserves. One of the critical problems of heavy oil or bitumen is that it takes large amounts of thermal energy and expensive catalysts to upgrade. E-Beam processing will allow lowering the thermal energy and sharply reduce the investment in catalysts. The design can be simpler and will contribute to lowering the production and transportation cost of heavy oil and bitumen.
Enhanced Rocker Tool used to Restore the Permeability of Formations: Case Studies
Authors: Almeida J. B. N. , Suzart J. W. P. , Paiva M. D. M. , Santos J. A. C. M. , Santos F. H. M. , Barbosa V. P. 
Published: May 2009

Abstract
The northeastern region of Brazil is the largest onshore oil producer in the country. However, regional oil production is still much less than offshore production in other Brazilian basins. Therefore, customized low-cost technologies are routinely employed locally to deal with issues, such as perforation plugging, scaling, and sediments production, for example. Heavy oil produced in this area builds up paraffin and asphaltene deposits over time, further decreasing productivity of the fields. This paper discusses applying a true fluidic oscillator (TFO), an enhanced rocker tool (ERT) that synergistically combines fluidic, acoustic, and chemical effects, to enhance the action of a fluid treatment on the formation. Usually, this tool is used in conjunction with coiled tubing (CT) equipment. Because the operator considered a CT operation too expensive for the needs of this region, the tool was run into the well with a regular work string as a lower-cost alternative. Three similar wells in the Potiguar Basin were selected and treated with diesel and butyl glycol through the TFO with significant improvement in estimated permeability and oil production (an increase of 20% to 240%) after treatment. Overall, the tool enhanced the treatment effectiveness by amplifying the contact area between fluids and formation. This demonstrated the applicability of this cost-effective solution for stimulation of low-productivity wells.