bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Recovery Performance of Miscible Displacement and WAG Process in Tight Oil Formations
Authors: Ghaderi S. M. , Clarkson C. R. , Chen S.. , Kaviani D.. 
Published: March 2012

Abstract
Recent advances in well design and production techniques have brought considerable attention to exploitation of tight (low permeability, absolute permeability &lt;1 mD) oil resources. Drilling of long horizontal wells and deployment of hydraulic fractures along these wells (multi-fractured horizontal wells) can substantially improve the primary production rates from such reservoirs. Nevertheless, the low effective permeability of these reservoirs to oil hinders the sustainability of favorable oil rates and at some point applying some EOR technique becomes inevitable.
In the current study, CO2 miscible flooding and WAG process in a tight oil reservoir are investigated. Although several studies have investigated different aspects of the process in conventional oil plays, the design of an effective scheme in tight oil formations is more complex. These complexities are related to the proper design of the fractures (half-length, conductivity, orientation (transverse vs. longitudinal), etc.) and their relative placement along producers and injectors and the operational constraints on each well or segment of the well.
In this work, we utilize an EOR scheme design where multi-fractured horizontal wells are used for both injection and production, and the hydraulic fracturing stages are staggered to delay breakthrough and improve sweep efficiency. For a set of defined parameters, compositional simulations are conducted to investigate the effect of the CO2 slug size, WAG ratio and cycle length on the recovery efficiency of the model. The recovery from the aforementioned EOR process is then compared with its corresponding base case in which the reservoir has gone through periods of primary and water-flooding stages. The results of this study show that the incremental oil recovery from WAG process in tight formation can reach as high as 20%.
Water Management and Microbial Control Programs in the Exploitation of Unconventional Hydrocarbons
Authors: Van Der Kraan Geert M. , Keene Philip A. , James Malcolm , Yin Bei , Williams Terry M. , van Ruiten Otto P. , Love Donald J. 
Published: March 2012

Abstract
Worldwide, the production of natural gas and now oil from shale basins (source rock) has been embraced as a commercially viable way of producing unconventional energy resources leading to a revolution in gas production in the US. Developments to invest in and tap into this alternative way of gas production are taking off in Europe and Asia. Hydraulic fracturing is a proven technology, used for many years to develop hydrocarbon resources. Successful strategies with hydraulic fracturing include the safe and effective use of chemical additives, proper well casing and robust water management programs.
During the exploitation of hydrocarbons from shales, chemical additives such as corrosion inhibitors, gelling agents, biocides etc, have to be used in the fracturing of wells. Sustainable chemistries and effective product stewardship programs are required to minimize environmental and human exposure hazards. The addition of water with organic molecules to the actual fractured wells makes these environments subject to unwanted growth of microorganisms and biofilm development, which has detrimental effects on hydrocarbon flow and leads to pipeline/equipment corrosion. Often the presence of sulfate reducing microorganisms leads to unwanted H2S production and subsequently souring. Due to this, water cycle management and properly designed microbial control programs for all water sources including injected water or produced water, are required. Because the microbial challenges and environmental parameters of these water sources vary, different microbial control strategies and treatments are required for each source.
New formulations of biocides and control programs aimed at the needs of the gas and oil industry have been developed, e.g. improved heat stability and the reduction in biocide levels to achieve the same level of microbial control. These newly developed microbial control technologies will be presented in this paper, and the related regulatory and product stewardship support will be shortly addressed.
After a Decade of Microseismic Monitoring: Can We Evaluate Stimulation Effectiveness and Design Better Stimulations
Authors: Wuestefeld Andreas , Urbancic Ted , Baig Adam , Prince Marc 
Published: March 2012

Abstract
Over the past decade, microsesimic monitoring has become the approach most oftenused to gain an in-situ understanding of the rock’s response during hydraulic fracture stimulations. From initial monitoring performed in the Barnett Shale to monitoring currently being carried out for example in the Horn River and Marcellus formations, we review the evolution of microseismic monitoring from the viewpoint of data collection (single versus multi-well array configurations, utilization of long lateral stimulation wells), to data analysis, to the incorporation of microseismic parameters to constrain and validate reservoir models.
Generally, we have observed that overall fracture height, width and length, orientation, and growth vary from formation to formation and within each formation, thereby highlighting the ongoing necessity for microseismic monitoring. Additionally, through the use of advanced microseismic analysis techniques, such as Seismic Moment Tensor Inversion (SMTI), details on rupture mechanisms have been used to assess stimulation effectiveness, define complex Discrete Fracture Networks (DFN) and provide estimates of Enhanced Fluid Flow (EFF), which assist in calibrating and validating reservoir models. Utilizing spatial and temporal distributions in DFN and EFF, along with estimates of fracture interconnectivity and complexity, the role of pre-existing fractures and fault structures in the rock matrix can be established and used to provide more realistic estimates of stimulation parameters such as Stimulated Reservoir Volume (SRV).
New Hydraulic Fracturing Process Enables Far-Field Diversion in Unconventional Reservoirs
Authors: Mcneil Fraser , van Gijtenbeek Klaas , Van Domelen Mark 
Published: March 2012

Abstract
The challenge in recovering hydrocarbons from shale rock is its very low permeability, which requires cost-effective fracturestimulation treatments to make production economic. Technological advances and improved operational efficiency have made production from shale resources around the globe far more viable; however, while the wells being completed today are proving to be reasonably economical, the question that remains is if the operators are truly capitalizing on their full potential.
In recent years, the industry has been in search of a better method to enable well operators to capitalize on the natural fractures commonly found in shale reservoirs. If properly developed, these natural fractures will create a network of connectivity within the reservoir, potentially improving long-term production when they have been propagated. In most shales, however, the stress anisotropy present can prevent sufficient dilation of the natural fractures during stimulation treatments. To induce branch fracturing, far-field diversion must be achieved inside the fracture to overcome the stresses in the rock holding the natural fractures closed. Increasing net pressure during the treatment will enhance dilation of these natural fractures, creating a complex network of connectivity, and the greater the net pressure within the hydraulic fracture, the more fracture complexity created.
Most of the various processes introduced previously are limited because multiple perforated intervals or large open annular sections are treated at one time. Also, to achieve the high injection rates required, they are treated down the casing, so that any changes made to the treatment require an entire casing volume to be pumped before these changes reach the perforations. This paper presents a case history of a multistage-fracturing process that allows real-time changes to be made downhole in response to observed treating pressure. This functionality enables far-field reservoir diversion to be achieved, ultimately increasing stimulated reservoir contact (SRC).
Probabilistic Reserves and Resources Estimation: A Methodology for Aggregating Probabilistic Petroleum Reserves and Resources
Authors: Galvao M.. , Hastenreiter L.. , Molina J.. , Quadros A.. , Montechiari J.. , Hamacher S.. 
Published: March 2012

AbstractThe oil industry strives to create an international standard for classification and estimation of resources since the 1930s. The goal is to provide investors with information obtained under the same assumptions, as to facilitate the comparison between petroleum companies. In 2007 the four major international organizations, Society of Petroleum Engineers (SPE), American Association of Petroleum Geologists (AAPG), World Petroleum Council (WPC) and Society of Petroleum Evaluation Engineers (SPEE), jointly released a single set of guidelines for classification and evaluation of oil and gas resources, the Petroleum Resources Management System (PRMS, 2007).Several methodologies for estimating reserves can be employed within the PRMS’s (2007) premises, which can be classified as deterministic or probabilistic. Unconventional resources emerge as a new frontier for the oil industry, thus implying high uncertainty levels in both technical and economic assessments. The main purpose of this paper is to explore this issue and to propose a correlation-based probabilistic methodology for aggregating oil and gas reserves of conventional and unconventional resources. The methodology is in accordance with the guidelines of the PRMS (2007) and with the new rules of the Securities Exchange Commission 2009 (SEC). The correlation assessment evaluates technical and operational features, and the probabilistic aggregation is performed by Monte Carlo Simulation (MCS).Besides the introductory section, this paper comprises four other sections. A literature review presents definitions of conventional and unconventional resources, and an examination of classification, estimation and aggregation of reserves, important for better understanding the following sections. The third section describes the proposed correlation-based probabilistic methodology. Afterward, a case study presents an application of the methodology. Finally, the last section synthesizes the main conclusions.
Real-Time Downhole Monitoring Of Hydraulic Fracturing Treatments Using Fibre Optic Distributed Temperature and Acoustic Sensing
Authors: Molenaar Mathieu M. , Fidan Erkan , Hill David J. 
Published: March 2012

Abstract
In order to make commercial and development decisions effectively and more rapidly, new appraisal and testing technologies are needed to maximize early data collection and subsequent subsurface understanding as quickly as possible. For Unconventional Gas and Light Tight Oil (UGLTO) projects, some of this critical data can be derived from hydraulic fracture stimulation and inflow profiling activities.
For UGLTO projects, achieving an optimum hydraulic fracture stimulation is a continuous endeavor beginning as early as possible; and balancing the cost of completion vs. production performance is critical as the completion/stimulation is a large cost component of the well and heavily influences production rate/ultimate recovery. The fast paced development and introduction of new completion technologies requires diagnostic technology that can help us understand stimulation effectiveness, assess new completion technologies, and evaluate which zones are the most productive.
One emerging technology, fibre optic distributed sensing has the potential of providing key insights during both the hydraulic fracturing and initial flowback. The passive nature of fibre optic sensors allows intervention-free surveillance, which makes fibre-optic technology an effective platform for permanent sensing in producing wells. Until recently, the oil & gas industry fibre optic sensing technology has focused mainly on temperature (DTS) profiling along the wellbore. In 2009, it was first demonstrated how fibre optic distributed acoustic sensing (DAS) can also be used for downhole applications. Where hydraulic fracture diagnostics based on DTS alone in the past sometimes yielded ambiguous results, the combination of both acoustic and temperature sensing provides a step-change improvement in the ability to perform real-time and post-job diagnostics & analyses of the stimulation.
The different horizontal well case studies presented in this paper will illustrate how the combination of DTS and DAS has the potential to enhance the monitoring, assessment, and optimization of openhole and limited entry designed hydraulic fracture stimulation treatments.
Study of Class G Cement Fatigue using Experimental Investigations
Authors: Kosinowski Christian , Teodoriu Catalin 
Published: March 2012

Abstract
This paper presents the results of laboratory investigation about fatigue of Class G wellbore cement exposed to radial loads under room temperature conditions.
While fatigue is well described for metals, wellbore cement fatigue is a rather unknown field. As well cements can be exposed to cyclic loading situations like in new oilfield technologies e.g. enhanced oil recovery by steam injection or geothermal applications using single-well-solutions, cement damage by fatigue becomes a more important issue. Cement integrity is crucial environmental and economic issue and no risk on cement failure should be accepted. The thermal induced loads in the reality were replaced by mechanical loads that recreates the stress situation on the cement. In order to evaluate the behavior of the cement, experiments were performed to investigate how cement reacts to cyclic loadings. A low number of cycles mean up to 100 loadings sequences. Samples of a pipe-cement-compound recreating the wellbore geometry are tested in a hydraulic press under axial loads. The stress situation in the cement sheath of the tested samples was calculated using a combination of numerical and analytical methods. Failure criteria were used to evaluate these calculations and could be used to predict future failure behavior. It has been found that fatigue of cement is rather similar for metal and cement at least in the low cycle range. For metals there is a specific stress limit where failure or significant damage to the material occurs within several cycles. This means, if the limit is exceeded the material will fail, maybe not at the first cycle, but it will fail over the cycles. Cement shows that this behavior is similar to metals, no other fatigue mechanisms like damage accumulation were observed, just a straight load limit.
Lessons Learned from North America and Current Status of Unconventional Gas Exploration and Exploitation in China
Authors: Ping Wang , Jiang Ruizhong , Wang Shichao 
Published: March 2012

Abstract
Unconventional gas has been paid more and more attention since the successful exploration in North America, China is no exception. Effective exploitation of unconventional gas can guarantee energy security, optimize energy structure and help protect environment in China.
Successful experiences from North America are summarized, current status of unconventional gas in China is analyzed from three aspects: resources, technologies, polices.
The success of North America profits from five reasons: governmental positive policies and tax preferences, advanced technologies, adequate pipeline infrastructure, small firms leading system, large demand of natural gas. China has large potential resources of unconventional gas. As to tight gas, the prospective resources of tight gas exceed 12 trillion cubic meters. For coal-bed methane(CBM), China is ranked 3rd after Russia and Canada and has 36.8 trillion cubic meters. China has just started shale gas study and has no definite evaluation. Until now, China has developed a series of technologies. For tight gas: high-precision 2D seismic, fast drilling, slim hole drilling. As for CBM: AVO response detect, penniform multi-lateral drilling and ultra-short radius jetting drilling. China has set many beneficial policies for unconventional gas especially for CBM, now the government is working hard on making positive policies and tax preferences for shale gas. There are several differences between North America and China: geological difference, land ownership, regulatory framework, pipeline network, small firms in America and national oil companies in China. Some suggestions are proposed for China: set positive policies and tax preferences, develop advanced and adaptive technologies, consummate natural gas market system and infrastructure, cooperate with foreign companies and monitor the effect of unconventional gas exploitation on environment. These summaries and suggestions can be instructive for other countries to develop unconventional gas.
Assessment of SAGD Well Configuration Optimization in Lloydminster Heavy Oil Reserve
Authors: Tavallali M.. , Maini B.. , Harding T.. , Busahmin B.. 
Published: March 2012

Abstract
Large quantity of heavy oil resources are present in variety of complex thin reservoirs in Lloydminster area which are situated in east-central Alberta and west-central Saskatchewan. Primary depletion and waterflooding are the principal recovery techniques. Although these techniques work, the recovery factors remain low and large volumes of oil are left unrecovered when these methods have been exhausted. Because of the large quantities of sand production, many of these reservoirs end up with a network of wormholes that makes most of the displacement type enhanced oil recovery techniques inapplicable. Because of these high conductivity channels, only gravity drainage based techniques have a good chance of success.
Among the applicable methods in Lloydminster area, SAGD has not received adequate attention, mostly due to the notion that heat loss in thin reservoirs would make the process uneconomical. While this may be true, the limiting reservoir thickness for SAGD under varying conditions has not been established. These reservoirs contain light oil with sufficient mobility. Therefore the communication between the SAGD well pairs is no longer a hurdle. This opens up the possibility of increasing the distance between the two wells and introducing elements of steamflooding into the process in order to compensate for the small thickness of the reservoir.
The main objective of this study was to evaluate the effect of well configuration on SAGD performance and develop a methodology for enhancement of the SAGD performance through optimizing the well configurations for Lloydminster type of reservoir.
A new well configuration was able to significantly improve the application of SAGD in thin reservoirs of Lloydminster. It provided high RF at reasonable cSOR. The effects of some common Lloydminster reservoir characteristics, which are problematic for the SAGD process (such as initial gas saturation, bottom water, and gas-cap) were investigated for the most promising well configuration.
Closed Loop Circulating Systems Enhance Well Control and Efficiency With Precise Wellbore Monitoring and Management Capabilities
Authors: Grayson B. , Gans A. H. 
Published: March 2012

Abstract
The greatest risk to operational safety during the drilling and completion of a well is a kick. A gas influx, with its potential for escalation into well control event, places the crew, the environment and the rig in imminent danger.
The second greatest risk is misdiagnosis of an event and the failure to quickly and correctly take action.
For kicks and other pressure related events, the question is often fundamental—"are we experiencing losses or is the well ballooning during a connection"? The answer can be critical. An incorrect decision based on a misdiagnosed situation can result in millions of dollars in non-productive time (NPT). In the extreme, incorrect diagnosis can lead to death and injury, environmental damage and the loss of the rig.
These risks to well control and drilling efficiency are being mitigated using a handful of common oilfield technologies that are the key elements of closed-loop circulating system—rotating control devices (RCDs), flow-metering technologies, automated drilling choke systems and downhole isolation valves.
This is truly an instance of the whole being greater than the sum of the parts. That value is being further enhanced through the integration of innovative analysis and management software. These closed loop systems have proven very successful in mitigating risk and improving economics across a wide range of land and marine drilling applications and are allowing the industry to safely tackle it’s most risk-laden and costly wells.
The elements are field proven—some with more than a 40-year history—readily available from numerous vendors and are relatively economical. Individually they add incremental safety and efficiency benefits. However, when these elements are paired or used in combination with each other to create a closed and pressurizable mud-returns system, the benefits escalate at an exponential rate.
This paper examines the basics elements of a closed-loop circulating system and how this technology is enhancing the safety and efficiency of drilling and completion operations without sacrificing other operational elements.
Use of the Continuous Circulation System on the Kvitebjørn Field
Authors: Ross N. , Scaife T. , Macmillan R. , Berg P. C. , Jenner J. W. 
Published: March 2012

Abstract
The reasons behind Statoil choosing to include continuous circulation in HPHT Managed Pressure Drilling operations in the Kvitebjørn Field in the North Sea are explained. The paper will also discuss the preparations for the operation and the equipment and manpower required to enable the Continuous Circulation System to be installed and operated on the platform. Results recorded by the drilling team during the drilling period are described. Reference is also made to other applications of the Continuous Circulation System.