bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Structured Approach for Probabilistic-Assisted History Matching Using Evolutionary Algorithms: Tengiz Field Applications
Authors: Cheng H. , Dehghani K. , Billiter T. 
Published: September 2008

Abstract
Model calibration or history matching has commonly been conducted on a single deterministic model by a "manual" trial-and-error approach. With recent advances in the application of design of experiments for using numerical models in probabilistic forecasting, the feasibility of the manual history match process used for a single deterministic model has become questionable.
In manual history matching, a structured approach is used in which the sequence of adjustments has been from global, then to flow units, followed by local changes in model properties. However, the applicability of this approach to probabilistic history matching has not been demonstrated. Moreover, the industry's lack of experience in using assisted history-matching tools and the careless application without using a structured logic that is based on engineering judgment can lead the users to several potential pitfalls resulting in unrealistic solutions.
This work shows that in using evolutionary algorithms, a structured (staged) assisted history-matching methodology can be applied by considering probabilistic ranges of relevant input parameters and tailored objective functions for each stage of the process. The key "heavy-hitter" parameters with the highest impact on the history-match process are identified and introduced through conducting sensitivity runs.
A physically-sound and proper set of parameters with realistic ranges are introduced at each stage of the history-match process in a logical order. This paper shows that a workflow can be designed so that the ranges of selected parameters that are used to attain the best solutions at each stage can be carried over to the next stage to continue the history-match process.
Since this workflow is conducted in a probabilistic semi-automatic manner, a diverse set of solutions can be obtained with the flexibility to guide the process as is traditionally done in manual history matching. The workflow is demonstrated through its application to history match production data from the Tengiz super-giant carbonate oil field located on the shores of the Caspian Sea in the Republic of Kazakhstan.
Extended-Stroke Downhole Power Unit Successfully Pulls Subsea Wellhead Plugs in the Gulf of Mexico
Authors: McDaniel Dennis , Cromb John , Walton Jim , Clemens Jack , Moore Darrell , Huggins Jeff 
Published: September 2008

Abstract
Today's need to provide deepwater subsea well servicing has created many new challenges for the industry. For example, pulling a deepwater subsea wellhead or crown plug can require an extreme pulling force. The difficulties experienced can be compounded by conditions when the plug has been in place for extended periods of time as well as the more demanding deepwater conditions, such as high differential forces and settlement on top of the plug that contribute to the need for the higher pulling forces. These conditions often exceed the capabilities of conventional slickline services. As exploration continues to venture into more challenging environments, service companies have had to increase the scope of capabilities of their equipment to meet the challenges brought about by the new environments that require capability for tools to pull high tensile loads. The deepwater subsea arena has been particularly challenging, and this paper will focus on a slickline innovation — an extended-stroke electro mechanical device — that can provide deepwater subsea well interventions more cost-effectively than other service alternatives.
The tool is a slickline-deployed electro-mechanical device that is operated by batteries rather than explosives or hydrostatic pressurized tools and can produce a high linear pulling force. Since first being introduced, the electro-mechanical device has undergone several changes that have increased its capabilities and functionality. For example, it has recently been configured for pulling subsea wellhead plugs.
This paper will present three case histories that discuss the first use of the ‘extended stroke’ electro mechanical device in the Gulf of Mexico in which it was capable of pulling plugs at a water depth of 5,339 feet as well as several subsequent case histories.
Using the slickline electro-mechanical device rather than coiled-tubing resulted in substantial savings in both the cost of deployment and rig time.
What Does Sustainability Mean to Petroleum?
Authors: Ebenhack Ben W. , Martinez Daniel M. 
Published: September 2008

Abstract
Sustainability can be a troublesome concept that many people find challenging even to define. The most commonly used definition is the one put forth for sustainable development by the Brundtland Commission in 1987: "development that meets the needs of the present without compromising the ability of future generations to meet their own needs." The term sustainability came into vogue on the heels of this report, which was published in a book entitled Our Common Future.i
The Brundtland Commission definition alludes to a balanced, judicious use of resources to provide decent lives for humanity both now and in the future. It is fundamentally a concept of equity; appreciating the needs of all people living and not yet born. This is a powerful challenge to the industries and people engaged in natural resource utilization.
The term sustainability has often been narrowed to refer to the mere longevity of an organization, group, or profits. This is myopic. Without appropriate attention to the sustainability of critical resources, nothing else is sustainable.. Likewise, this term has somehow pitted the valued petroleum resource against what are still speculative technologies (i.e. the alternatives) rather than addressing how we must judiciously use petroleum now to benefit our future.
Beyond that, the dominance of a global resource economy creates a profound set of connections across the world. The industrialized world depends on energy imports from around the world. At the same time, it places everyone in the world in competition for the same resources, as scarcities loom. Recognizing these connections can support a strong utilitarian motivation to consider equitable access to resources.
Directional Success in the Canadian Rockies: Dynamic Tools Enable Accurate Comparison of Drill Bit Designs
Authors: Barton Steven , Lockley Russ 
Published: September 2008

Abstract
A smooth torque response is widely regarded as one of the greatest challenges when drilling with a drill bit on a directional assembly. Aspects such as toolface control and stick-slip are both proportional to the torque generated by the bit, and by nature, fixed cutter (FC) drill bits are capable of generating high levels of torque. If large changes in downhole torque are produced while drilling, these 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 reviews the field performance of a number of drill bits within the Canadian Rockies on directional assemblies. Particular focus is placed on the torque response and its resultant effect on both the steerability and stability of the assembly. The analysis includes comparison of conventional FC drill bits and roller cone (RC) designs, and also documents performance of specific FC designs that are equipped with torque controlling features. These features, in combination with specific cutting structure layouts, are engineered to provide predictable torque response while being optimized for high rates of penetration. The bit designs also include a unique gauge geometry that was engineered to reduce drag and deliver improved borehole quality.
The field performance review includes downhole dynamics data analysis. The recorder used gathers drilling dynamics data at a high frequency sample rate, enabling lateral stability and the variance in downhole rotation of the drill bit to be accurately determined. Evaluation between the different drill bit concepts revealed that use of FC designs with specific torque control features provided toolface control equal to or greater than a RC design. Steerability and stability were improved when compared directly to conventional fixed cutter designs, with resultant increase in penetration rates. Successful application has resulted in significant time and cost savings to operators.
Next-Generation Perforating System Enhances the Testing and Treatment of Fracture Stimulated Wells in Canada
Authors: Bell M. R. G. , Cuthill D. A. 
Published: September 2008

Abstract
Ineffective perforation can adversely affect the completion of fracture stimulated wells in several ways. If the interval is to be tested prior to fracturing, a clean connection to the formation is required to facilitate meaningful data acquisition. Excessive perforation damage can mask true formation potential and lead to incorrect diagnosis and decision making. Inadequate perforations can result in significant fracture tortuosity, increasing formation breakdown pressure – occasionally beyond the capacity of surface equipment or design rating of the well. Finally, limited entry perforation – a common technique for diverting a treatment across multiple fracture initiation points – demands that as many perforations as possible are open and can accept treatment fluids. Low perforating efficiency and variations in perforation cleanup associated with heterogeneous formations can cause uneven treatment distribution and suboptimal completion.
Traditional methods for achieving clean perforations depend on creating a pressure gradient between formation and wellbore to induce flow and remove debris from the perforation tunnels - this can be difficult to accomplish, especially in low-pressure reservoirs. Underbalance cleanup favors intervals with higher flow potential – typically those with greater permeability - and may result in low perforation efficiency in poor or variable quality zones. Operators of wells requiring fracture stimulation are therefore faced with a significant challenge to find reliable, cost-effective perforating methods.
A new class of reactive shaped charges has recently been introduced that generates a powerful secondary effect within each perforation tunnel immediately after it is formed. The reaction supercharges each tunnel, causing a surge of flow into the wellbore that removes all compacted debris and the near-tunnel crushed zone that would otherwise impair flow performance. Since this effect is independent of rock properties and wellbore conditions, a very high percentage of clean tunnels can be obtained across the entire interval without necessarily perforating in an underbalanced condition.
This paper describes the new charge technology in greater detail and reports on its successful deployment in more than a dozen wells for different operators in Canada. Specific examples are used to illustrate how the system facilitates pre-frac evaluation, fracture initiation and limited entry fracture stimulation.
Development of an Expandable Liner Hanger With Increased Annular Flow Area
Authors: Jackson Tance , Watson Brock , Moran Larry 
Published: September 2008

Abstract
Several criteria are important for a cementing operation as it relates to effective zonal isolation. First of all, studies have shown that cementing operations can be improved by rotating and reciprocating the liner. In addition, it has been shown that increased flow rates (prior to cementing, during cementing, and during displacement) can improve zonal isolation. While currently available expandable liner hanger technology can achieve the required liner movement, rotation, and reciprocation to affect a good cement job, these capabilities alone have not been capable of always meeting cementing needs in every scenario.
When expandable liner hangers were introduced to the oilfield, they were immediately accepted. Experience has shown that increasing flow rates (prior to cementing, during cementing, and during displacement) can offer improved zonal isolation. A new liner hanger was designed to increase the annular flow area, subsequently reducing annular friction pressure to allow higher flow rates. The added bypass area would also provide reduced surge to the formation while running the liner. This would shorten liner installation times. In addition, by increasing the bypass area, the possibility of solids bridging at the liner hanger (which can cause loss of circulation during circulating and cementing) would also be reduced. When loss of circulation occurs, proper cement placement is jeopardized.
This paper highlights the development of the new smaller-outside-diameter (OD) expandable liner hanger. This project was commenced; the new liner hanger has a pre-expansion maximum outside diameter that is smaller than the outside diameter of conventional liner hanger's tie-back receptacles and integral top-set packers. The new smaller diameter expandable liner hanger maintains the desirable features of existing expandable liner hanger.
Computer modeling including Finite Element Modeling (FEA) will show the design analysis for the expandable liner hanger. Additionally, prototype testing will be performed to validate the new design.
The new expandable liner hanger design offers the capabilities to rotate and reciprocate during circulating/cementing and displacing; a simple, robust design for installation reliability; and gas-tight liner-top sealing.
Determining Multilayer Formation Properties from Transient Temperature and Pressure Measurements
Authors: Sui W. , Zhu D. , Hill A. D. , Ehlig-Economides C. A. 
Published: September 2008

Abstract
Multilayer transient testing commonly relies on a series of step rate changes in surface flow rate with acquisition of stabilized rate profiles before each rate change and stationary downhole transient rate and pressure measurements after each rate change. The procedure requires one rate change for each layer to be characterized, and overall test duration can be quite long depending on the number of layers to be characterized. This study introduces an entirely new testing approach that uses transient temperature data at multiple locations together with a single-point transient pressure measurement. Because the temperature sensors acquire multipoint temperature simultaneously, this technique requires only one surface flow rate changes, thereby reducing the test duration significantly.
A coupled wellbore/reservoir thermal model developed in a previous study showed that the combination of transient temperature and pressure is sufficiently sensitive to individual layer properties to determine layer permeability and skin values in multilayered systems. In this work, the inverse problem is solved using the Levenberg-Marquardt regression algorithm.
In this new testing method, temperature data from only n+1 locations are required to determine layer permeability and skin values in an n-layer reservoir, and strategic sampling over time accelerates the regression convergence. The inversion has been tested on many synthetic cases with wide variations in layer permeability and skin values and has proven to be both accurate and robust. In addition, temperature resolution and data signal to noise impacts have been studied along with a data filtering approach that enable selection of suitable pressure and temperature sensor technologies for applying the new testing method. With the interpreted permeability and skin values, well productivity can then be enhanced by hydraulically fracturing in low permeability layers and/or by applying matrix stimulation in layers with high skin.
An Integrated Approach to Reservoir Uncertainty Assessment: Case Study of a Gulf of Mexico Reservoir
Authors: Sharma A. , Leung J. , Srinivasan S. , Kim Y. 
Published: September 2008

Abstract
Integrated uncertainty analysis of a carbonate reservoir in the Gulf of Mexico was performed to quantify the contribution of factors such as lithofacies definition criteria, reservoir structure, total and fracture porosity, net-to-gross cut-offs, and measurement scale disparities on geologic uncertainty. An innovative approach to derive facies definition criteria and net-to-gross cut-offs based on k-mean cluster analysis is presented. A detailed analysis of scale up of petrophysical properties using the variance of mean concept was performed and its implication on geologic model uncertainty was assessed. Finally, innovative approaches to verify and visualize spatial uncertainty models are presented.
A detailed geologic model for the fractured carbonate reservoir was available and the study objective was broken down into an assessment of uncertainty due to: i) structural model, ii) sedimentary model, iii) petrophysical model, and iv) scaleup/upscaling. Systematic investigation of each of these aspects as well as a fully probabilistic integration of uncertainty models was performed.
Uncertainty in original oil in place was computed by sampling from the component distributions. The study results indicate that the OOIP exhibits significant sensitivity to factors such as cut-offs for lithofacies and net-to-gross definition. An important result that points to a paradigm shift in uncertainty modeling is the sizeable contribution of scale-up to the uncertainty models. The results further reveal that the determination of net-to-gross and lithofacies definition thresholds using cluster analysis vastly enhances the accuracy of the prediction of net-pay at a new well location.
The paper presents a complete workflow for integrated reservoir uncertainty assessment. Besides demonstrating the use of data analysis tools such as cluster analysis for deriving more robust criteria for facies and net-to-gross definition, a fundamental contribution of this paper is to demonstrate the role of scale up on uncertainty assessment. While this has been alluded to by several researchers in the past, this paper is the first to demonstrate a modeling workflow that explicitly handles uncertainty due to scale up and promotes the notion of "soft" conditional simulation.
Entrance Pressure of Oil Based Mud into Shale: Effect of Shale, Water Activity, and Mud Properties
Authors: Oleas Andres , Osuji Collins E. , Chenevert Martin E. , Sharma Mukul M. 
Published: September 2008

Abstract
Oil-based muds (OBMs) have been developed to combat drilling problems often caused by shale hydration. Therefore, it is of utmost importance to understand the interaction of OBMs as they contact shales. Past research (Chenevert 1970) has shown how the movement of water from OBMs can be controlled by the addition of salt. This paper deals with the movement of the oil phase of the OBM, as described by its hydraulic "Entrance Pressure." Although the oil filtrate of the OBM does not hydrate the shale, it can penetrate and flow into the shale at a certain entrance pressure. Such flow into shale can be as damaging as water flow, because it increases the pore pressure of the shale, which can cause wellbore failure. It is of primary interest to understand this when using OBMs in shales. It is also important to understand how factors such as the emulsifier concentration in the OBM and the porosity of the shale affect this entrance pressure.
The objective of this study is to perform laboratory tests in order to determine and quantify the factors that control the entry pressures for shales. For this purpose, five OBM samples with different emulsifiers and oil and water concentrations were prepared. The study was also intended to derive an understanding of the effects of shale porosity on entrance pressure. In order to vary the porosity of the test samples, it was convenient to place them in various controlled environments with relative humidity (i.e. water activities). Data are reported for Arco China shale samples having porosities of 1.8% (native), 3.9%, and 4.9%, at water activities (aw) of 0.72, 0.86, and 0.96, respectively.
It was observed that as the emulsifier concentration increased, the oil breakthrough pressure increased. It was also observed that as the porosity of the shale is reduced (smaller pore throats), the entrance pressure for the mud increases.
Petrophysical Properties Prediction Using 3D Core Scanner Imagery
Authors: Jouini Soufiane , Umbhauer Francois , Leduc Jean-Pierre , Keskes Noomane 
Published: September 2008

Abstract
This paper deals with the use of core scanner imagery for discriminating main representative rock textures, to improve core high resolution petrophysical log quality and to propose a better strategy for plugs sampling. The idea of using tomography images has physical bases. In fact, scanned data is representative for rock bulk density changes; the perceptual texture of these images reveals features like granularity, mineralogy, both tied to porosity distribution. In this paper we demonstrate that, core scanner images contain information that can be related to petrophysical properties. This paper presents a fully automated method based on a stochastic approach for textural analysis and segmentation of core scanner images. The technique used to obtain image models is related to new image processing techniques based on texture models. The accuracy of the model is a key point for confidently linking images and physical or geological properties. This approach is demonstrated through stochastic synthesizing procedure proving a fundamental link between texture perception and rock physical properties. The proposed workflow is (i) to use 3D scanned cores images as a vector of continuity for automatically describing petrophysical facies and (ii) to extrapolate petrophysical properties along cores in order to produce a high resolution core petrophysical log.
A validation of this method is provided through comparison with "hand made" petrophysical facies description. Synthetic petrophysical properties curves have also been compared to curves issued from conventional kriging of core data. Blind test procedures were used to evaluate the efficiency of our technique in regard to porosity, density, Archie's formation and cementation factors and mineralogy (clay volume). Also, as lower performance is observed for permeability estimation an alternative solution is proposed for improving the prediction of this latter property.