bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cement Sheath Durability: Increasing Cement Sheath Integrity to Reduce Gas Migration in the Marcellus Shale Play
Authors: McDaniel Jessica , Watters Larry , Shadravan Arash 
Published: June 2014

Abstract
This study examines the effects of drilling, completion, and production operations and their associated cyclic stresses on a cement sheath. The operations performed after cement placement can damage cement sheath integrity and bond with the casing or formation resulting in loss of zonal isolation and sustained casing pressure often requiring remediation and reducing productivity.
This paper describes evaluation of cement sheath failure resulting from cyclic stresses experienced while drilling, fracturing, and producing shale gas wells and showcases optimization of cement systems used for Marcellus shale play intermediate casing strings. This study correlates the durability of each cement system with mechanical properties of the cements to determine each system's ability to resist failure under cyclic stresses. Two different cement compositions were used to cement intermediate casings on a number of wells. Both had similar performance properties and were designed to prevent gas migration following cementing. Wells cemented with one of the blends experienced a higher incidence of seal failure as evidenced by sustained casing pressure. In laboratory stress endurance testing, each cement system failed at a specific quantified magnitude of cumulative energy input. The results show a higher maximum endurance for the more durable cement, which also exhibits the higher field success rate. The fatigue endurance limit gives an approximation of the stress magnitude that a cement composition can withstand. Correlating laboratory endurance measurements and mechanical properties of the cement systems to field performance further quantifies the mechanical properties needed to optimize zonal isolation.
U.S. shale gas production is a major component in the future of U. S. energy supply. As such, there is focus on the drilling and production of U.S. shale plays. This study takes measured look at annular seal failure and lays the ground work to calibrate it to actual field results allowing operators and service companies to select more durable cement systems. Results from this study can ultimately decrease time and funds spent repairing compromised cement seals. Furthermore, improved seal performance equates to improved well performance with lessened environmental risk and impact.
Addressing UBO and MPD Challenges with Wired Drill Pipe Telemetry
Authors: Pixton David S. , Shishavan Reza Asgharzadeh , Perez Hector D. , Hedengren John D. , Craig Andrew 
Published: June 2014

Abstract
Wired drill pipe (WDP) telemetry has been used in over 100 wells worldwide to create a drillstring network that provides high bandwidth communications between tools deployed in the wellbore and the surface. When applied to managed pressure drilling (MPD) and underbalanced operations (UBO), wired drill pipe offers substantial benefits. Because of its independence from fluid flow, it gives visibility to downhole conditions where never before possible, including environments where traditional telemetry methods are not supported, and time intervals where pumps are not operating. Similarly, memory-quality data can be provided real-time from measurement tools located in the bottom hole assembly (BHA) as well as at points along the drillstring. Specific case studies and lessons learned from using wired drill pipe in the underbalanced and managed pressure drilling environments are summarized, as are recent enhancements to the wired drill pipe system, and their impact on extending the operating envelope and reliability of wired drill pipe.
Methods for leveraging the increased quantity and quality of real-time data to improve the drilling process are important if the highest value is to be obtained from high-speed telemetry technology. To this end a novel automated borehole pressure (BHP) control system with predictive technology has been designed. A preliminary UBO case study is used to assess the performance of this controller during different drilling events, including a drill pipe connection procedure and an unexpected gas influx. While making a connection, the controller maintains tight pressure control and may enable efficiency improvements by allowing faster trip speeds, when offered as part of an automation system. For the gas influx case, the ability of the controller to properly control the influx is shown to be dependent on low latency communications, such as that provided by WDP. This controller offers a substantial decrease in time required to control influx events as compared to manual methods and earlier controllers.
A nonlinear model predictive controller and a nonlinear estimator are used in the automation study. Information available from multiple sensors arrayed in a WDP system was found to be very useful in model parameter estimation, including friction factor and annular fluid density.
Proper application of WDP technology to challenges experienced in the UBO/MPD environment can yield more cost effective and successful deployment of these methods, further improving the value UBO/MPD technology can provide. Future work will included continued development of the control system to more fully capture the value of wired pipe technology.
The First Application of Whole Process Underbalanced Drilling in Ultradeep Horizontal Well in Tarim Oilfield
Authors: Xueqing Teng , Pei Yang , Ning Li , Chengxin Yang , Yan Jin , Yunhu Lu , Bo Zhou , Xiaoliang Wang , Feng Zhang , Tao Zhang , Xiaohong Zhou 
Published: June 2014

Abstract
In Tarim Oilfield the Ordovician carbonate reservoirs develop lots of cracks and caves. The formation pressure is very low(&gt;6000m, less than65MPa), leading to the narrow mud weight window(MWW) problem. Serious lost circulation and reservoir damaged was encountered when we use the traditional overbalanced drilling method, also the oil and gas reservoirs cannot be discovered timely, therefore whole process underbalanced drilling technique must be employed. The underbalanced drilling technique has been applied in the narrow MWW formations, but there’s no report of the whole process underbalanced drilling technique (including the underbalanced drilling, underbalanced tripping, underbalanced logging and underbalanced completions, etc.) being used in such formations in China.
Based on the analysis of difficulties encountered by traditional overbalanced drilling methods such as serious lost circulation, horizontal wells cannot reach the design sections, serious damage to the reservoir, the feasibility analysis and construction plan of the whole process underbalanced drilling in Y block is proposed. The first whole process underbalanced drilling of horizontal wells in Tarim Oilfield was conducted and completed. Finally 6 layers of reservoirs are being discovered (2 layers are not discovered by the prospect well), the cumulative thickness is 16m, which increases the rate of oil and gas discoveries.
Compared with the on-site well, the efficiency of drilling is greatly improved, no lost circulation and no complex situation encountered; the ROP increases 74% compared to the adjacent wells in the same layers. It also created the deepest drilling depth record using the inflatable mud in China. The whole process underbalanced drilling program formed in this thesis provide an effective drilling and completion mode for the Y block in Tarim Oilfield, which greatly increased the rate of oil and gas discoveries, and reduce non-productive time, while this method has some reference significance for the low-pressure reservoir development in the other parts of the world.
Fit-for-Purpose Modeling for Automation of Underbalanced Drilling Operations
Authors: Aarsnes Ulf Jakob , Di Melgio Florent , Aamo Ole Morten , Kaasa Glenn-Ole 
Published: June 2014

Abstract
Automation has the potential to improve efficiency, precision, and safety of pressure and flow control during underbalanced drilling (UBD). In addition, advanced estimation theory can be used to extract more information from existing measurements to increase knowledge of the downhole conditions during operation.
An essential part of an advanced (model based) pressure control system is the hydraulic model. Even with high-bandwidth distributed downhole measurements, a calibrated hydraulic model is required to ensure robustness, e.g. to sensor loss, and obtain real time estimates of unmeasured quantities and reservoir characteristics.
In UBD operations, in contrast to Managed-Pressure-Drilling (MPD) operations, the flow in the annulus is inherently a multiphase gas liquid flow, which severely complicates the modelling. Much effort has been put into developing multiphase flow models, however, to date; most of these are very complex, requires extensive configuration and are not well suited for real-time applications. Consequently, a major gap with respect to automation of UBD is the lack of a fit-for-purpose model capable of reproducing the main dynamics of the multiphase flow in the annulus, while being sufficiently robust and suitable for real-time applications.
In this work, we present recent advances on the development of a simplified fit-for-purpose model of the distributed gas-liquid dynamics, suited for advanced control of UBD operations. Using an automated calibration procedure, the model is shown to retain accuracy in a realistic case study. It is also shown that its reduced complexity enables real time coupling with measurements to obtain estimates of unmeasured quantities such as gas distribution and perform reservoir characterization.
MudCap Drilling: New Variations, Drivers, Limitations, and Lessons Learned – Case Histories
Authors: Goodwin Bob , Nauduri Sagar , Medley George 
Published: June 2014

Abstract
MudCap Drilling (MCD), a major variation of Managed Pressure Drilling (MPD), is a key drilling technology that can help drill zones with total lost circulation otherwise not drillable using conventional methods.
Multiple variations of MCD have evolved, including: a) Floating MudCap Drilling (FMCD), b) Pressurized MudCap Drilling (PMCD), and c) Dynamic MudCap Drilling (DMCD). Case histories serve as a guide to understand the variations and their application during drilling. Drivers and limitations for each of the MCD variants are addressed, as are engineering, planning and training needs associated with each variant.
Additionally, an in-depth case history of a recent five-well MCD program in the Texas panhandle Granite Wash formation is presented, describing the process the operator employed to investigate, select, design and deploy Dynamic (constant injection) MudCap Drilling. The case history describes the pros and cons and the criteria justifying MCD as the preferred solution, including the prerequisites to successful deployment of MCD. The paper describes the design process and equipment deployed, highlights the integration of conventional services with the unconventional, and presents challenges, highlights and lessons learned from these drilling activities.
Impact of Experimental Studies on Unconventional Reservoir Mechanisms
Authors: Rosen Richard , Mickelson William , Sharf-Aldin Munir , Kurtoglu Basak , Kosanke Tobi , Paiangle Meghana , Patterson Robert , Mir Faraz , Narasimhan Santhosh , Amini Amir 
Published: June 2014

Abstract
Novel apparatuses have been developed to measure permeability using steady- and unsteady- state methods on nano-Darcy (nD) shale (source rock) using intact cylindrical samples returned to isostatic effective reservoir stress. The steady-state method uses a high pressure dual pump system using supercritical fluids. High pressure supercritical fluids have low viscosity and low compressibility. The effect of low viscosity fluid results in measureable flow rates and the effect of low compressibility fluid minimize unsteady-state transients thereby reducing the amount of time required to achieve steady-state equilibrium. Specially designed and configured pump systems, seals and sleeves reduce leak rates to allow Darcy flow and permeability determination below 1 nD. The unsteady-state method is based upon standard designs but is optimized for small pore volume. In this report we present a summary of over 200 such permeability measurements. Permeability is observed to be dependent on geologic parameters, such as, texture and composition. Stress dependence, with hysteresis, is observed for samples with and without fractures as is rate dependent skin (Forchheimer). An interpretation model where matrix storage feeds a progressively larger fracture network provides a logical basis for a dual-porosity reservoir simulation model. This dual-porosity model is used to understand the influence of reservoir production parameters, such as choke management.
An additional observed effect is possibly related to pore collapse and disconnection. Pores associated with organic matter are softer than the surrounding mineral matrix. If these pores have a sufficiently small throat diameter, it is not hard to envision that they easily compact and close under increased effective stress as the result of reservoir depletion. Therefore, organic pore systems can become isolated unlike those of a sponge where fluids remain in pressure communication at all times. The implication of such pore isolation phenomena is that fluid material balance is not preserved during production and can contribute to large production decline rates.
Simulation of Liquid-Rich Shale Gas Reservoirs with Heavy Hydrocarbon Fraction Desorption
Authors: Haghshenas B. , Soroush M. , Brohi I. , Clarkson C. R. 
Published: June 2014

Abstract
Liquid-rich shale (LRS) gas reservoirs have gained increasing attention in recent years. The Eagleford Shale in the U.S. and the Duvernay Shale in Canada are examples of liquid-rich shale gas plays which are being exploited to produce more profitable liquid hydrocarbons with natural gas. These reservoirs may store liquid hydrocarbons in liquid or vapor state, as with gas condensate systems. Further, shale gas reservoirs may contain significant volumes of organic matter, which stores gas (and liquid hydrocarbons) in the adsorbed state.
There have been several historical simulation studies investigating the impact of various reservoir and fluid properties on fluid production and recovery from LRS, however none have investigated the importance of desorption. Adsorption has previously been suggested to be an important storage mechanism in organic-rich shales, particularly for heavy hydrocarbon fractions. Matrix pore configuration and associated connectivity has also been previously demonstrated to be an important control on gas production from shale gas reservoirs, but the impact on condensate production has not been investigated for LRS.
In this work, the impact of heavy hydrocarbon fraction desorption, pore configuration and connectivity, fluid composition and operating conditions (flowing bottomhole pressure) on LRS production is investigated using a commercial simulator. We use PVT data from previous studies to develop a compositional simulation model analog of an LRS reservoir. Hydrocarbon component adsorption amounts are modeled using the Langmuir isotherm. Different combinations of organic and inorganic matter and fracture porosity, and their connectivity, are also assigned in the simulation cases.
Simulation sensitivities demonstrate that desorption can contribute significantly to condensate production, depending on fluid composition and pore connectivity. In cases where liquid-fraction adsorption contributes significantly to in-place volume, we recommend injection of light end gases to mitigate condensate blockage. This will be studied in detail in future work.
Are the Laboratory Measurements of Proppant Crush Resistance Unrealistically Low?
Authors: Getty J. , Bulau C. R. 
Published: June 2014

Abstract
Crush resistance has become a key, perhaps even the singular, parameter used in selection of proppant for hydraulic fracture stimulation operations. The API Recommended Practice 19C (RP19C)—which is identical to the ISO13503-2 standard1— lays out procedures intended to produce repeatable results.
However, repeated measurements in the same lab are inherently noisy and lab-to-lab results often produce crush strength differences of as much as 2k psi. The RP19C is intended to produce reliable and repeatable proppant crush results. However, results from this study show that when compared to other possible methods, the RP19C procedure both increases the noise in the measurement and lowers the crush rating. We describe a series of experiments which provide statistically reliable insight on the effect that loading and handling of the crush cell has on the crush results. The data allow a comparison of five loading methods: the standard RP19C method; the Pluviator; a jarred-cell approach to test the RP19C admonition to avoid "agitating" the cell; a vibratory settling method and a new mechanical loader, designed by the authors. Because two of the loading methods produce statistically significant improvements in crush resistance (specifically the vibratory method and the new mechanical loading device) and because the primary effect appears to be tied to maximizing the packing density, we conclude that the in-situ crush resistance of these proppants may be higher than estimated by the standard test.
Induced Fracture Complexity, When is it Really Required in Unconventional Reservoir Stimulation?
Authors: Sierra Leopoldo , Mayerhofer Mike 
Published: June 2014

Abstract
Induced fracture complexity maximization, in addition to the primary hydraulic fracture, to improve the recovery efficiency or productivity of gas or liquids in unconventional reservoirs has been accepted and fully implemented by the industry. As a result, stimulation fluids and/or completion strategies have been engineered to maximize induced fracture complexity in many unconventional reservoirs. In typical horizontal completions, induced fracture complexity with sustained conductivity is clearly beneficial for the productivity of nanodarcy (nd) shales, although this might not be a requirement for all unconventional reservoirs, especially tight sands.
In some unconventional reservoirs, operators have observed similar productivity in wells with predominantly planar fractures compared to wells that appear to have more complex fractures. This paper, supported by extensive reservoir simulations, aims to develop criteria for situations in which induced fracture complexity and sustained conductivity are required and when they are not. The simulations include a reservoir permeability range of 10 nd to 0.001 md and a complexity or secondary fracture conductivity of 1 to 5 md-ft. The results show that the fracture complexity and sustained conductivity are generally important for reservoir permeabilities lower than 100 nd for gas and 500 nd for liquid-producing reservoirs.
Based on these results, an optimized completion strategy is suggested to maximize the productivity or recovery factor (RF) in unconventional gas- and liquid-producing reservoirs.
New Type Curve Analysis Removes Limitations of Conventional After-Closure Analysis of DFIT Data
Authors: Craig David P. 
Published: June 2014

Abstract
Prefrac pressure diagnostics, including fracture-injection/falloff sequences, have been used for several years to estimate initial reservoir pressure and transmissibility in unconventional reservoirs. Prior to performing pressure diagnostics, initial or average reservoir pressure is almost always unknown, and many times the purpose of a pressure diagnostic is to determine initial reservoir pressure. As shown by several authors, when a pressure diagnostic falloff exhibits bilinear, linear, or radial flow, the initial or average reservoir pressure can be determined from special plots using straight-line analysis methods. However, correctly identifying the flow regimes during a pressure falloff is often very difficult, and the tendency is to incorrectly apply straight-line analysis methods to data on a specialized plot that often does not correspond to a bilinear, linear, or radial flow regime. In many cases, bilinear, linear, or radial flow will not be observed in any of the falloff data, and valid estimates of initial reservoir pressure and transmissibility cannot be determined using straight-line methods.
This paper presents a new type curve analysis method that removes the limitations of conventional after-closure straight- line analysis of pressure diagnostics. Like conventional well test analysis, the new method fits observed pressure data to analytical type curves, and type curve match points are used to determine initial reservoir pressure, transmissibility, fracture half-length, fracture conductivity, and fracture damage. Type curve analysis has proved especially useful for post-frac evaluation of stimulation effectiveness, and has also proved useful in shale reservoirs where it is often difficult to determine if a dilated fracture or fracture network close completely, with no conductivity or retained residual width. Understanding dilation/contraction properties of a shale fracture network can provide important guidance for fracture treatment design and optimization. Type curve analysis has also reduced the amount of shut-in time required to obtain a quantitative estimate of reservoir and fracture properties albeit with increasing uncertainty as shut-in time decreases.
Statistical Reverse Model to Predict Mineral Composition and TOC Content of Marcellus Shale
Authors: Wang G. , Carr T. R. , Ju Y. 
Published: June 2014

Abstract
Unconventional shale reservoirs possess low matrix permeability and cannot produce economically without effective placement of horizontal laterals and effective hydraulic stimulation.It is critical to recognize brittle units amenable to hydraulic fracturing and rich in organic matter. Shale mineralogy affects not only the effectiveness of stimulation, but also the ratio of free to absorbed gas. Heterogeneity in shale reservoirs expressed by mineral composition, organic matter richness and brittleness significantly influences shale-gas production. Although providing the necessary information, core data and pulsed neutron spectroscopy (PNS) logs are limited by cost considerations to an insufficient number of wells in order to sufficiently characterize reservoir heterogeneity.
We present an approach of petrophysical analysis and statistical reverse modeling to better determine mineral concentration, organic matter percentage, and volume of gas and water using conventional logs in the Marcellus Shale (Appalachian basin, USA). Core data and PNS logs are utilized to guide and demonstrate the results. The statistically based reverse model incorporates random errors of logging, and solves mineral composition through matching the or iginal logs with mineralogy models. The effectiveness of statistical reverse models is enhanced through removing the effects of minerals with significant petrophysical response (e.g., barite) and fluids. Barite strongly affects the mineralogical estimates in shale. The concentration of such minerals can be predicted by the difference between PE curve and a trend line. Fluid volumes are predicted by a modified shaly-sand model with uranium concentration through understanding the effect of organic matter.
The methodology proposed provides an approach to predict mineral composition and organic richness and the corresponding mineralogical properties (e.g., geomechanical and free-to-absorbed gas ratio). The proposed approach aids in recognizing geologic and engineering targets, designing horizontal well trajectories, targeting fracturing strategies and understanding shale depositional environments and processes. The proposed approach can be extended to other organic -rich shale reservoirs.