bluuebunny/crossref_metadata_2025_split huggingface dataset:
Placing Two Fractures Consecutively in Close Proximity to Significantly Increase Revenue-to-Cost Ratio
Authors: Surjaatmadja Jim B. 
Published: October 2008

Abstract
Though fractures caused by stimulation will likely propagate away from high-permeability areas, the stimulation often provides a significant production improvement because of the large flow-path increase created by the fracture. This fact can be hard for many to accept. Placing two fractures consecutively in close proximity to each other may offer a tremendous benefit. With this approach, the first fracture is placed conventionally into the maximum stress direction. After a short delay, the second fracture is then placed, taking advantage of the temporary stress modification caused by the opening of the first fracture.
This delay is computed so the stress modification at the tip of the second fracture is always maximized. This is done so that the second fracture will extend into the original (natural) minimum stress direction, meaning the fracture will extend into highly permeable areas and, therefore, production expectations from the second fracture will potentially be much larger than production of the first fracture. This leads to a significant increase in the revenue-to-cost ratio. In other words, a significant revenue increase can be achieved with an incremental cost increase.
This new approach uses conventional pin-point stimulation methods; therefore, even though it is "new," it carries a very minimal risk with a potentially large payout. This paper discusses how the new process can be effectively performed by harnessing a pseudo-Maxwell/Kelvin-Voigt, creep phenomenon that is normally present in rock. The paper will also examine formation geology, reservoir aspects, best practices, better completion schemes, simulation data, and different stimulation and perforating techniques that would be best used for achieving maximum productivity.
Successful Open Hole Smart Completion, Case History from Saudi Arabia
Authors: Al-Amri Khalifah M. , Al-Nassir Abdulmohsin A. , Zhou Shaohua 
Published: October 2008

Abstract
Over the last several years Saudi Aramco embarked on a technology driven strategy to maximize well productivity and total oil recovery by converting existing weak horizontal producers or dead vertical wells to MRC (maximum reservoir contact) wells. Another application is drilling new MRC wells from surface, many of which, if required by reservoir management, were installed with downhole smart systems to control flow from each lateral. Most of these wells were drilled with cemented 7" conventional liner or worked over with 5-1/2" expandable liner for zonal isolation as well as conduit for smart completion in the reservoir.
This paper will present an alternative to convert existing old wells to smart MRC wells equipped with hydraulically controlled downhole valves and swell packers or feed-through open hole packers as zonal isolation in open hole environment. So far four such wells have been successfully worked over and completed with open hole smart completion. Production data shows that not only these wells have achieved significant production gains, but also confirmed that the downhole isolation packers and flow control valves functioned as planned. This paper will also highlight the cost saving advantage of open hole smart completion as well as operational optimization process that led to successful field implementation.
EOS-Based Downhole Fluid Characterization
Authors: Zuo Julian Y. , Zhang Dan , Dubost Francois , Dong Chengli , Mullins Oliver C. , O'Keefe Michael , Betancourt Soraya S. 
Published: October 2008

Abstract
Downhole fluid analysis (DFA), together with wireline formation testing tools, provides real-time measurements of reservoir fluid properties such as compositions of four or five components/groups and gas/oil ratio (GOR). With the introduction of a new generation of DFA tools that analyze fluids in situ, the accuracy and reliability of the DFA measurements are significantly enhanced. Furthermore, the downhole measurements of live fluid density and viscosity are integrated into the new tools. Direct pressure and temperature measurements of the flowline ensure capture of accurate fluid conditions. To further enhance these advanced features, a new method of downhole fluid characterization based on the equation of state (EOS) approach is proposed in this work.
The purpose of this work is to develop a new approach to maximize the value of DFA data and perform quality assurance and/or quality control (QA/QC) of DFA data. The basic inputs from DFA measurements are weight percentages of CO2, C1, C2, C3-C5, and C6+; live fluid density; and viscosity. A new method is developed in this work to delump and characterize the measurements of C3-C5 (C2-C5) and C6+ into full-length compositional data. The full-length compositional data predicted by the new method are compared with the laboratory-measured gas chromatograph (GC) data up to C30+ for more than 1,000 fluids, including heavy oil, conventional oil, volatile oil, rich gas condensate, lean gas condensate, and wet gas. A good agreement is reached.
Furthermore, based on the delumped and characterized compositions, an EOS model is established that can be applied to predict fluid phase behavior and physical properties on the basis of DFA data as input. The EOS predictions are validated and compared with the laboratory-measured PVT (pressure/volume/temperature) properties for more than 1,000 fluids. The GOR, formation volume factor (FVF), and density predictions are in good agreement with the laboratory measurements. The established EOS model is then able to predict other PVT properties, and the results are compared with the laboratory measurements in a good accord.
CO2 and Flue Gas Coreflood Experiments for Enhanced Coalbed Methane
Authors: Mazumder Saikat , Wolf Karl Heinz 
Published: October 2008

Abstract
Laboratory core flooding experiments with CO2, N2 and flue gas were carried out on coal in an experimental high P, T device under in-situ conditions. These experiments will be able to give an insight into the design of the injection system, management, control of the operations and the efficiency of an ECBM project. Although the experience gained by the oil industry represents a valuable starting point, several problems are still to be studied and solved before CO2 improved deep coalbed methane production may be operationally feasible. These are all related to the heterogeneous nature of the pore structure of coal, and in particular the presence of fractures. More specifically, a number of questions need to be addressed, e.g. what are the conditions under which the fluid in the micro-pores of the coal is displaced by the CO2 in the presence of competitive adsorption; what is the role of compositional heterogeneity and fracture anisotropy of coal for the injection design and the efficiency of the sequestration in relation to the swelling and shrinkage characteristics of coal; how does the mobile and the immobile water in the coal affect the exchange process. These questions can be answered by means of downscaled laboratory experiments that are capable of accurately describing the coupled process of multiphase flow, competitive adsorption, and geo-mechanics. In the laboratory conditions have been simulated to match pressure and temperature at depths of 800 to 1000 m. Under those conditions the injected CO2 remains supercritical. Upto now, the results show that dewatering will be an essential step for successful ECBM combined with a CO2 sequestration process.
Differential Swelling and Permeability Change of Coal in Response to CO2 Injection for ECBM
Authors: Mazumder Saikat , Wolf Karl Heinz 
Published: October 2008

Abstract
The matrix volume of coal swells when CO2 / CH4 adsorb on the coal structure. In coalbed gas reservoirs, matrix swelling could cause the fracture aperture width to decrease, causing a considerable reduction in permeability. On a unit concentration basis, CO2 causes greater degree of coal matrix swelling compared to CH4. Much of this difference is attributable to the differing sorption capacity that coal has towards carbon dioxide and methane. This condition in a coal reservoir would lead to differential swelling. Differential swelling will have consequences in terms of porosity / permeability loss, with serious implication for the performance and implementation of carbon sequestration projects.
Coal can be understood as a macromolecular cross-linked polymeric structure. An experimental effort has been made to measure the differential swelling effect of CO2 / CH4 on this macromolecular structure and to theoretically translate that effect in terms of porosity and permeability. A unique feature of this work is that, real time permeability measurements were done to see the true effect of differential strain from CH4 saturated coal core flooding experiments.
Innovative Well Operations from a DPII Vessel: A Case Study
Authors: Glennie Simon , Leeson Tom , Rowson Ian 
Published: October 2008

Abstract
The traditional need to carry out all well operations from a rig can be expensive and delays valuable well construction programmes. Rigless intervention, including the use of subsea wireline lubricators and installing subsea Xmas trees on wire, utilising a Dynamically Positioned (DP) intervention vessel has long been accepted in some areas of the world as a cost-effective and efficient alternative to traditional rig-based methods.
In 2005 it was recognised internally that the ability to intervene without a traditional rig would be of potential future benefit. An aspirational work programme was developed including both well operations such as subsea Xmas tree (SSXT) change out, well abandonment and production enhancement operations was developed. The scope generated was sufficient to justify the mobilisation of a suitable vessel and the necessary specialist equipment such that these operations could be completed. It was also recognised that the vessel would offer further options for construction support, commissioning start up support and field maintenance activities. The actual 1st job undertaken of SSXT installation on Vincent project was not recognised as a possibility until late 2006.
To date 7 SSXT installation operations have been completed successfully in approx. 370m of water on the Vincent field in Australia, this was followed by wireline intervention to commission wells for operation to/from the host facility. A number of plugged and abandoned wellheads were also severed and recovered from the seabed. The vessel was also utilised extensively for other subsea operations. Operations are ongoing to complete the expansion of the Vincent project and a number of production enhancement opportunities are being planned for the near future including PLT surveys, water shut offs, and Gas-lift valve installation.
This paper will detail the operations undertaken and the issues to be managed to ensure safe and cost-effective execution. Furthermore the paper examines the unique challenges of translating experience gained to date to the Asia-Pacific region, to deeper water depths, and will discuss the lessons learnt from the planning and operations phases of the project. These will include details of the modifications required to the vessel to convert her from her previous role as a large Supply Vessel (PSV), including the critical elements of the conversion required in order to ensure appropriate Class registration and the successful award of an Australian Safety Case covering all safety critical operations.
Lastly the paper will examine the potential benefits Rigless intervention can offer and the additional cost benefits of incorporating other non-well related activities into the vessel programme.
Performance of Polymer Flood in Sanand Field, India-A Case Study
Authors: Tiwari Deepti , Marathe R. V. , Patel N. K. , Ramachandran K. P. , Maurya C. R. , Tewari P. K. 
Published: October 2008

Abstract
Twenty two years of history of polymer flood in KS-III sand in Sanand field, Gujarat State, India, proves the efficacy of the process in a reservoir of 85°C temperature. KS-III sand of Middle Eocene age, is one of the few successful cases of polymer flooding in such high reservoir temperature. Reservoir is acting under partial edge water drive. Oil viscosity of 20 centi poise led to adverse mobility ratio which resulted in cusping of water in structurally higher wells. Hence polymer flood was considered the best option in this reservoir for improving mobility ratio of oil and overall areal and volumetric sweep efficiency which was also supported by the laboratory studies on native cores of the field. Polyacrylamide polymer was selected for injection.
Polymer flood process in Sanand field has undergone many stages of implementation. After initiation of polymer pilot in an inverted five spot pattern in 1985 with one injector, 4 producers and one monitoring well, it was extended to four inverted five spot patterns in 1993 with nine producers and four injectors. Effect of the injection was visible in terms of reduction in water cut, improvement in oil production and increase in reservoir pressure. Success of pilot projects encouraged to full scale field implementation in 1996–97. Polymer injection was done in peripheral pattern in the main part of the field. Subsequent reviews have been carried out from time to time and mid course corrections have been taken accordingly.
Current paper discusses different stages of development in polymer flood, the steps taken from time to time, lessons learnt and conclusions drawn on the basis of practical experience and reservoir simulation.
Measuring the Effectiveness of Hazard and Risk Awareness Interventions Utilising a Virtual Reality Risk Perception Measurement Simulation
Authors: McGrath Tim 
Published: October 2008

Abstract
In this study oil and gas workers' Risk Perception was measured by their ability to detect, assess and react appropriately to realistic occupational hazards presented in a computer virtual reality simulation. This technique provides immediate results to determine whether attendees have benefited from training. Whilst all participants benefited from the training, some benefited more than others due to the appropriateness of the training for their current level of Risk Perception. This paper presents two successful training techniques which lead to an improvement in Risk Perception of the participants. It is anticipated that further testing with larger sample sizes will identify the components that are best suited to each level of participant.
Successful Case History of a Novel Open-Hole Horizontal Well Completion in Saudi Arabia
Authors: Al-Naimi K. M. , Lee B. O. , Shourbagi S. M. , Kelkar S. K. , Shaheen M. , Johnston B. 
Published: October 2008

Abstract
Horizontal completion technology has progressed dramatically over the last six years, with the latest technical barriers being eclipsed with open-hole technology. These completions have allowed multiple zones to be fractured and the benefits of utilizing open-hole horizontal completion technology have been well documented. The efficiencies and benefits of utilizing open-hole completion with mechanical isolation, has lead to the operational benefits of multiple fracturing operations being pumped in one continuous operation equating to time savings, more efficient fractures, faster cleanup and less safety hazards. Conventional methods of cementing a liner in place, perforating, fracturing and repeating the process for the number of stages required can be very time consuming with added expense of removing the frac plugs with coiled tubing after the operations have been completed.
When drilling a horizontal well, there are two preferred completion options. First, the horizontal section can be completed open-hole or with slotted/preperforated liner. In these completions effective stimulation along the horizontal wellbore is almost impossible. The second completion system, cased/perforated liner, requires cementing the production liner and running multiple isolation systems to effectively treat different sections of the wellbore. Multiple coiled tubing trips and multiple rig-up and rig-down of the stimulation equipment is required. These multi-stage horizontal completions take weeks to complete at high costs and elevated risks. Ultimately, the high completion costs or the lack of production due to ineffective stimulation make many reservoirs uneconomical to exploit.
This paper will discuss the new completion designed specifically for open-hole fracturing of both sandstone and carbonate reservoirs. This innovative, field proven system greatly increases the effectiveness of fracturing operations by segmenting the lateral and producing mechanical isolation points in the wellbore using the high performance open-hole packers. The system allows precision placement of fracturing fluids to maximize post-fracture productivity of the well. The completion system is run as part of an uncemented liner and spaced out based on the required number of stages. Once in place the packers are hydraulically set and fracturing treatments are pumped in separate stages but as a single continuous operation. By eliminating cementing requirements, natural fractures are undamaged and easily stimulated during pumping operations.
Facts and Data on Environmental Risks—Oil and Gas Drilling Operations
Authors: Rana S. 
Published: October 2008

Abstract
Purpose of the paper is to review environmental aspects of Oil & Gas drilling in view of economics of the projects benefiting industry professionals. Oil & Gas exploration, including offshore & directional drilling pose long and short-term environmental risks. These risks are primarily associated with (a) contamination due to drilling wastes (muds, produced waters, byproducts, etc.); emissions from drilling sites and potential runoffs, (b) natural gas/oil leaks and spills, and (c) direct effects on human health. The drilling fluids circulated through the well hole contain toxic materials (including oil/grease, arsenic, chromium, cadmium, lead, mercury, & naturally occurring radioactive materials). The composition of drilling muds and produced waters varies widely depending on location & depth of well; and type of drilling fluid. Produced waters potentially impacting the surface or groundwater are typically disposed of in a deep aquifer, but there is still the threat of accidental release from temporary storage. Contributing to air pollution are also the potential emissions of hydrogen sulfide present in natural gas deposits. Its short & long-term direct effect on human health could be severe, from unconsciousness to death within a few breaths. Statistically, 0.5-1% of exploratory wells result in blowout, causing harmful emissions. Additionally, pressurized contents of a geologic formation literally explode out of the new well, severely impacting environment and the project economics.
The paper includes summary statistics of environmental incidences, their causes & preventions based on actual projects. The accidents are related to well drilling, pipelines incidents and spills/leaks listed by cause (equipment failure, corrosion, joints, materials, etc.).
Paper presents guidelines and economically feasible options to minimize risks to environment & human health. It also provides an overview of the environmental concerns, project economics and sustainability issues.
Decline Curve Analysis of Oil Production in Low Permeability Reservoirs with Great Heterogeneity
Authors: Huo Da , Li Li , Fan Xiaodong , Yu Yanmin , Li Kewen 
Published: October 2008

Abstract
There have been many models of decline curve analysis in estimating reserves and production in petroleum reservoirs. It is difficult to evaluate the models because the true value of reserve in oil reservoirs is usually unknown. Previously, comparison and analysis among limited models has been made using spontaneous imbibition data. In this study, an approach to using core flooding experimental data was proposed to verify and evaluate the decline curve analysis models. Four representative models (exponential, hyperbolic, harmonic, and the mechanistic Li-Horne models) were chosen to predict and match the oil production in low permeability core samples and oil reservoirs. A systematic comparison among the four models was conducted by using the sum of squared residuals, regression coefficient, and the true values of reserve (for core samples) as the evaluation parameters. Both experimental and reservoir data from a low permeability oil reservoir with great heterogeneity were used. It was found that it was difficult to appraise the goodness of the decline curve analysis models by using the sum of squared residuals and regression coefficient as judging parameters in some cases. The small values of the sum of squared residuals or the great values of the regression coefficient could not guarantee small error in the predicted reserves. It may be a suitable approach to using experimental data of oil production in core samples with different permeability to evaluate decline curve analysis models. The results demonstrated that the Li-Horne model and the exponential model predicted the reserves satisfactorily for experimental data of water flooding in the core samples with low permeabilities.
Energy from Abandoned Oil and Gas Reservoirs
Authors: Zhang Lingyu , Yuan Jianguo , Liang Hongbin , Li Kewen 
Published: October 2008

Abstract
Petroleum and Geothermal industries are embracing the present boom in production of crude oil and power generation. At the same time, longevity or sustainability of this boom is worried about. In petroleum industry, a lot of oil and gas wells have been or will be abandoned. There have been few ideas and methodologies regarding how to utilize the abundant resource left in the oil and gas reservoirs. In this study, we pointed out that these oil and gas reservoirs might be transferred into exceptional enhanced geothermal reservoirs with very high temperatures by oxidizing the residual oil with the injected air. A concept to generate power from these exceptional enhanced geothermal reservoirs by using geothermal power generation technology was proposed. Using Du84 reservoir (heavy oil) in Shuguang oil field, and Ren9 reservoir (light oil) in Renqiu oil field, both from PetroChina as examples, we estimated the possible energy and the income that might be generated from such exceptional enhanced geothermal systems. We speculated that both the oil and geothermal industries will boom much longer based on this study.
The Potential of CO2-EOR in China Offshore Oilfield
Authors: Xiang W. , Zhou W. , Zhang J. , Yang G. , Jiang W. , Sun L. , Li J. 
Published: October 2008

Abstract
In South China Sea, the geological reserve of CO2 is huge. With the unanimous agreement of a series of problems caused by CO2 emissions, as an effective method to consume CO2, CO2 injection for enhanced oil recovery (EOR) has been investigated and reported by many researchers.
An extensive review of previous reported CO2-EOR projects is provided in this paper. According to exploring and analyzing the factors influencing CO2-EOR, and combined with the specialty of offshore conditions, reservoir evaluation of China offshore CO2-EOR is suggested in this paper. Based on the evaluation suggestion, the Chinese offshore oilfields were screened and the South China offshore oilfield close to CO2 reserve was conformable. This paper also describes the feasibility of CO2-EOR in the South China offshore oilfield from fundamental studies. The relationship of reservoir oil and CO2 showed that reservoir oil had good dissolving capacity to CO2. CO2 could effectively dissolve in and displace residual oil. The experimental results show that under reservoir conditions, CO2 could be in the one-contact miscible at 20 MPa, a slight higher than the formation pressure of 17.27 MPa. CO2 and oil could be in near miscible under formation conditions. The lab research work funded a further investigation on application of CO2-EOR in China offshore oilfield.