bluuebunny/crossref_metadata_2025_split huggingface dataset:
Duststones on Mars
Authors: Bridges Nathan T. , Muhs Daniel R. 
Published: March 2015

ABSTRACT
Dust is an abundant material on Mars, and there is strong evidence that it is a contributor to the rock record as “duststone,” analogous in many ways to loess on Earth. Although a common suite of dust formation mechanisms has operated on the two planets, fundamental differences in environments and geologic histories have resulted in vastly different weighting functions, causing distinct depositional styles and erosional mechanisms. On Earth, dust is derived predominantly from glacial grinding and, in nonglacial environments, by other processes, such as volcanism, eolian abrasion, and fluvial comminution. Hydrological and biological processes convert dust accumulations to loess deposits. Active hydrology also acts to clean dust from the atmosphere and convert loess into soil or erode it entirely. On Mars, glacial production of dust has been minor, with most fine particles probably produced from ancient volcanic, impact, and fluvial processes. Dust is deposited under arid conditions in which aggregate growth and cementation are the stabilizing agents. Thick accumulations result in duststone.
Focusing the Search for Biosignatures on Mars
Authors: Oehler Dorothy Z. , Allen Carlton C. 
Published: March 2015

ABSTRACT
The search for martian biosignatures can be enhanced by focusing exploration on locations most likely to contain organic-rich shales. Such shales both concentrate and preserve organic matter and are major repositories of organic geochemical biomarkers in sediments of all ages on Earth. Moreover, it has been suggested that for Mars, accumulations of organic matter may be the most easily detected and least ambiguous of possible biosignatures (Summons et al. 2010). Since current surface conditions on Mars are unfavorable for preservation of organic matter, focusing exploration on locations predicted to contain ancient organic-rich shales would offer one of the best chances of detecting evidence of life—if it ever evolved on the planet.
Orbital data can be used to evaluate regional sediment sources and sinks on Mars, and, based on that, facies can be predicted and locations identified that are most likely to contain organic-rich sediments. An example is presented from Acidalia Planitia, in the martian lowlands, where this approach led to the conclusion that facies in southern Acidalia were likely to be dominated by fine-grained, muddy sediments. That conclusion added weight to the hypothesis that mounds in Acidalia are martian versions of mud volcanoes as well as the suggestion that organic materials, if present, would have been deposited in the same area as the mounds. This allowed speculation that potential mud volcano clasts in Acidalia could include preserved, organic biosignatures and, thus, that the mounds in Acidalia constitute an untested class of exploration target for Mars.
Facies prediction using orbital data is particularly applicable to planetary exploration where ground truth is most often lacking but orbital data sets are increasingly available. This approach is well suited to the search for potential geochemical biomarkers in organic-rich shales. The approach additionally could be applied to exploration for other categories of biosignatures (such as stromatolites or morphologically preserved microfossils) and to more general planetary objectives, such as the search for hydrothermal sediments, carbonates, or any particular type of geologic deposit.
Stratigraphic Architecture of Bedrock Reference Section, Victoria Crater, Meridiani Planum, Mars
Authors: Edgar Lauren A. , Grotzinger John P. , Hayes Alex G. , Rubin David M. , Squyres Steve W. , Bell James F. , Herkenhoff Ken E. 
Published: March 2015

ABSTRACT
The Mars Exploration Rover Opportunity has investigated bedrock outcrops exposed in several craters at Meridiani Planum, Mars, in an effort to better understand the role of surface processes in its geologic history. Opportunity has recently completed its observations of Victoria crater, which is 750 m in diameter and exposes cliffs up to ∼15 m high. The plains surrounding Victoria crater are ∼10 m higher in elevation than those surrounding the previously explored Endurance crater, indicating that the Victoria crater exposes a stratigraphically higher section than does the Endurance crater; however, Victoria strata overlap in elevation with the rocks exposed at the Erebus crater. Victoria crater has a well-developed geomorphic pattern of promontories and embayments that define the crater wall and that reveal thick bedsets (3–7 m) of large-scale cross-bedding, interpreted as fossil eolian dunes. Opportunity was able to drive into the crater at Duck Bay, located on the western margin of Victoria crater. Data from the Microscopic Imager and Panoramic Camera reveal details about the structures, textures, and depositional and diagenetic events that influenced the Victoria bedrock. A lithostratigraphic subdivision of bedrock units was enabled by the presence of a light-toned band that lines much of the upper rim of the crater. In ascending order, three stratigraphic units are named Lyell, Smith, and Steno; Smith is the light-toned band. In the Reference Section exposed along the ingress path at Duck Bay, Smith is interpreted to represent a zone of diagenetic recrystallization; however, its upper contact also coincides with a primary erosional surface. Elsewhere in the crater the diagenetic band crosscuts the physical stratigraphy. Correlation with strata present at nearby promontory Cape Verde indicates that there is an erosional surface at the base of the cliff face that corresponds to the erosional contact below Steno. The erosional contact at the base of Cape Verde lies at a lower elevation, but within the same plane as the contact below Steno, which indicates that the material above the erosional contact was built on significant depositional paleotopography. The eolian dune forms exposed in Duck Bay and Cape Verde, combined with the geometry of the erosional surface, indicate that these outcrops may be part of a larger-scale draa architecture. This insight is possible only as a result of the larger-scale exposures at Victoria crater, which significantly exceed the more limited exposures at the Erebus, Endurance, and Eagle craters.
Fit-For-Purpose Acoustic Cement Evaluation Using Logging While Drilling in Deepwater
Authors: Fuller George Allen , Gupta Nadish , Blyth Matthew , Aparicio Alfredo 
Published: March 2015

Abstract
Cement evaluation is a critical part of a cementing operation. Recent industry events and the continuous tightening of regulations for cement placement have elevated the importance of cement evaluation to heights greater than ever. The initial verification of a primary cement job is performed using the pressure trend obtained while pumping, because the pressure increases as the cement rises in the annulus. The actual pressure trend can then be compared with the expected pressure to infer the actual cement height in the annulus; however, this methodology can only predict but not confirm the top of cement (TOC). In deepwater, the regulatory agencies may require physical evaluation of TOC in specific strings of the well that can require running cement bond log (CBL) tools for those strings. This would use the critical path time for every CBL run. In addition, this regulatory agency requirement can also be technically challenging because cement bond evaluation for casing as large as 18-in. that is placed in a 22-in. open hole is the upper threshold limit for conventional wireline conveyed CBL tools. Many operators are now runing logging-while-drilling (LWD) sonic tools for open hole compressional data. Using the same sonic tools, logging can be performed through the casing strings on the same run and the results can be analyzed to confirm the TOC. The data presented here seems to show that the results agreed well with the predicted TOC from the pumping data. The use of this tool for cement evaluation was further validated against CBL evaluation that was performed on deeper strings in example deepwater exploration wells. The paper will elaborate on how the integration of this technology can provide precise TOC evaluation and save the operators considerable rig time per section.
Clay-Free High Performance Water-Based Drilling Fluid for Extreme High Temperature Wells
Authors: Galindo Kay A. , Zha Weibin , Zhou Hui , Deville Jay P. 
Published: March 2015

Abstract
Growing demands to operate in harsh high temperature environments require robust drilling fluid performance to drill in such conditions. Water-based drilling fluids offer significant environmental advantages compared to invert-emulsion fluids (IEFs). High performance (HP) water-based drilling fluids are particularly advantageous compared to conventional water-based systems because they offer faster rates of penetration (ROPs), enhanced hole cleaning and shale inhibition, and improved wellbore stability. Most HP water-based drilling fluids can only tolerate operating temperatures up to 300°F attributed to a strong dependence on biopolymer-based viscosifiers. Thus, deeper exploration in extreme high temperature reservoirs (&gt;300°F) requires new drilling fluid technologies. A new high performance, high temperature water-based drilling fluid that is thermally stable at 400°F has been developed to meet these demands.
The new fluid system was fully formulated using a multimixer, and the resulting fluids were hot rolled at 150°F for 16 hours to condition the fluid before testing. The conditioned fluids were then further subjected to dynamic or static aging conditions with temperatures ranging from 300 to 400°F. The aged fluid viscosity was examined using a direct-indicating viscometer, and the pH was determined with a pH meter. The fluid loss properties of the fluids were determined by both API filtration and high-pressure/high-temperature (HP/HT) filtration at 350°F in according with the API recommended practice.
This paper presents the detailed study of the high performance, high temperature water-based drilling fluid formulated with 10.0-17.0 lbm/gal densities. The fluid exhibits a stable rheological profile. For example, a 14.0 lbm/gal formulation aged at 150°F for 16 hours yielded a plastic viscosity of 29 cp and a yield point of 22 lbm/100 ft2. After static aging for 48 hours at 400°F, the fluid gave a plastic viscosity of 27 cp and yield point of 24 lbm/100 ft2. The new fluid maintains stable viscosity, adequate suspension, low shear strength, shale stability, and filtration control up to 400°F.
This thermally stable, clay-free system exhibits good shale inhibition and is environmentally acceptable for both land and offshore drilling. This HP water-based drilling fluid is formulated with a novel synthetic polymer viscosifier and filtration control agent, allowing removal of thermally labile biopolymers without the addition of clay-based viscosifiers. The new formulation provides reliable thermal stability that can readily function in extreme high temperature wells, while preserving the benefits of HP water-based drilling fluids.
Innovative and Modular Equipment Design for Rheology and Compatibility Measurement of Complex Wellbore Fluids
Authors: Sairam P K , Pangu Ganesh , Gajji Bhargav 
Published: March 2015

Abstract
Accurately measuring the rheology of fluid systems under downhole conditions is recommended for the success of well construction. The rheological fingerprints of fluids and their admixtures deployed downhole during wellbore servicing provide a basis for predicting interfacial fluid movements and associated effects on bottomhole circulating pressures. Rheology measurements can also provide a direct indication of any detrimental physical and/or chemical reactions that might occur when the fluids intermix and/or contaminate one another during and after the placement process.
A need has existed for some time within the industry for high-pressure/high-temperature (HP/HT) rheology equipment capable of in-situ fluid transfer to change compositions on-the-fly, and easy to clean and maintain considering the abrasive and settable nature of cementitious fluids. This paper discusses an innovative design developed for a fully automated slurry rheometer capable of dosing contaminant fluids in and out of fluid samples to vary composition, mix homogenously in-situ, and measure compatibility between fluid systems at various volumetric compositions—all while maintaining in-situ wellbore test conditions.
The rheometer cell is a four-piece design that houses a novel magnetically coupled double helical rotor with cut flights and intermeshing helical blades on the stator to allow mixing and measuring at the same time while overcoming operational issues, such as wall-slip, particle settling, sample coring, and aid in-situ homogenization. A first of its kind, noncontact, zero friction magneto-resistive torsion measurement module with selectable range capabilities and large separation offset (6 to 8 in.) from moving parts is discussed in addition to its usability on both thick pastes as well as thin fluids.
A separate design of a high pressure slurry dosing unit that allows for compatibility measurements is discussed. Operating principles, design concepts, engineering development for modularity, calibration data, and slurry test results are presented.
Using Drill Cuttings Waste as Resource for Spud Mud
Authors: Taghiyev Farid , Hodne Helge , Saasen Arild 
Published: March 2015

Abstract
Today oil-contaminated drill cuttings are regarded as a waste in the oil industry and have to be treated before simply depositing in an onshore facility. Thermal technology to treat contaminated drill cuttings, remove most hydrocarbons and recover the subsurface material in a dry powder form exists. Due to the similarity between subsurface rock mineralogy and conventional bentonite used in the drilling fluid industry an extended laboratory study was carried out to evaluate the possibility of spud mud development using thermo-mechanically treated drill cuttings.
A total number of 28 spud mud compositions were prepared including two commonly used bentonite spud muds and tested in accordance with the API 13B-1 practices. An aging experiment was conducted as well to evaluate the stability of the designed fluids. Moreover, application of barite as a weighting material and short chain CMC polymer as a fluid loss control agent was investigated as well.
As a result of the conducted experiments stable seawater-based spud mud compositions with application of xanthan gum and thermo-mechanically treated drill cuttings were developed. The designed fluids have comparable properties with the conventionally used spud muds. Depending on the composition plastic viscosity varied from 6 to 12 cP and yield stress varied from 1.53 to 5.11 Pa. The fluids were stable and capable of suspending heavy barite particles. The CMC polymer demonstrated good fluid loss control qualities. The new fluids might be cost effective in case of weighted muds and when drilling through impermeable formations.
This paper shows in detail how cleaned drill cuttings can be recycled into new drilling fluid materials, which brings environmental benefits along with the economical benefits. The designed spud muds with application of drill cuttings are ready to be tested in a large-scale facility.
Accuracy and Correction of Hook Load Measurements During Drilling Operations
Authors: Eric Cayeux , Skadsem Hans Joakim , Kluge Roald 
Published: March 2015

Abstract
Hook load is a very important parameter used during drilling operations to control the weight on bit and to assess possible deteriorations of the downhole conditions such as poor hole cleaning or excessive tortuosity. However, the quality of the hook load measurement is often regarded as quite poor. This paper investigates the sources of uncertainties associated with the hook load measurement and proposes correction methods in order to obtain better data quality.
In practice, the hook load is normally measured indirectly, either in the travelling equipment or as a tension in the dead-line. This apparent hook load is subject to load-generating forces between the measurement location and the top of the string, including the weight of the mud hose attached to the top drive, imperfect tension transmission across sheaves and gravitational and inertia forces associated with weight and rotation of the drill line, respectively. The load contribution from these forces can amount to several metric tons and this must be accounted for whenever the true hook load is to be derived.
In this paper, a mathematical model describing the forces affecting the hook load measurement is developed. The model predicts true hook load as a function of block position, velocity and other conditions that can influence the measurement like the mud weight or whether the dolly is retracted or not. It is a generalization of the industry-standard hook load estimation technique and successfully replicates a number of trends observed in the field. Extensive model evaluation is performed by comparing model results to field measurements of simultaneous travelling equipment and dead-line tension derived hook loads. The model is also compared with data from a laboratory scale test rig equipped with distributed load cells connected to a data acquisition system.
The hook load correction model works exclusively at the software level and represents a potentially cost-efficient alternative to a direct hook load sensor installed in the internal BOP of some top drives. Assessment of model uncertainty and its effect on hook load predictions is given particular attention as this ultimately determines whether the correction method can replace direct hook load measurements in practice.
A New Technique for Calculating Downhole Rotation Speed and Torque from Surface Measurements
Authors: Kyllingstad Åge 
Published: March 2015

Abstract
This paper presents a new, field tested technique that provides accurate estimates of downhole variables rotation speed and torque. The estimates are based on drill string geometry and surface measurements of the same variables. The technique is more wide-ranging and accurate than previously used methods, in several ways. First, it includes many frequencies, not only the stick-slip frequency. This helps to detect higher order stick-slip oscillations and to determine maximum and minimum speed more accurately. Second, it works when the top drive speed varies substantially, which is often the case when the top drive speed control is softened as a result of activating a stick-slip mitigation tool. Third, it also provides downhole torque, not only rotation speed. Finally, the new method can be used for calculating string variables at any location, not only at the bit.
The new method has been tested with exceptionally good results, both against an advanced, comprehensive simulation model, and against field data containing synchronized and high quality downhole and surface data. It is especially encouraging that the method works well when the torque input is erratic with a low periodicity and also when the top drive speed varied substantially. This strongly indicates that the new method can be used as a reliable and low cost technique for evaluating and validating the effect of various stick-slip mitigation tools.
First Ever North Sea Deployment of Tandem DIV System Eliminates Snubbing- A Case Study
Authors: Mueller Gary 
Published: March 2015

Abstract
On an offshore jackup rig in the North Sea, an operator required specific drilling needs during tripping and the safe and efficient deployment of the completion string without killing the well. A solution other than a snubbing unit was required because of the length of the completion string, which included 12 swellable packers for 13 individual zones. The swellable packers were staged to prevent the heel and toe effect and to create a homogeneous production profile. Snubbing the pipe in and out of the hole presents serious Health, Safety and Environmental issues that typically lead to considerable non-productive time (NPT) due the inherent slow speed of operation associated. In addition, snubbing requires added personnel.
To address these concerns and provide for a safer, less expensive and efficient method of tripping pipe, the operator chose to employ a Downhole Isolation Valve (DIV) solution that allowed for the process to be performed in a conventional manner under conditions of complete well control. As an alternative to a snubbing unit, the DIV system was used to isolate the slightly underbalanced well. The service team installed a tandem 7-in., 32-lb, 5K DIV system (Fig. 1) on a temporary retrievable tieback casing string with premium left-hand thread connections. Specifically, a tandem DIV system was chosen as an added security measure, in the case that unforeseen circumstances required an additional unit. Figure 1Upper and lower DIV system configuration.
In this paper the author will examine and provide details of the DIV system and its' evolution. He will go on to describe how the North Sea's first ever successful deployment of a tandem downhole deployment valve (DIV) system created a reliable barrier that isolated the well formation pressure below the valve, thereby saving rig time, enhancing safety, and cutting drilling costs.