bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resolution and Accuracy of Neutron-Gamma Density Measurements Compared to Conventional Gamma-Gamma Density Measurements
Authors: Luycx Mathilde , Torres-Verdín C. 
Published: October 2017

Abstract
Density measurements are widely used for the in-situ assessment of formation porosity. Traditionally, bulk density is measured with a Gamma-Gamma density tool using a radioactive chemical source. Neutron-Gamma density was recently developed to infer porosity with non-chemical sources. It is therefore imperative to quantify the differences in spatial resolution and accuracy between the two measurements and the corresponding impact on petrophysical interpretation practices.
We designed a theoretical, albeit practical logging-while-drilling (LWD) Neutron-Gamma density tool and optimized source-detector spacing for maximum accuracy. The tool design comprises a 14 MeV neutron source, two gamma ray detectors and two fast neutron detectors. Counts ratios are used to establish a linear relationship with formation bulk density. This design yields an accuracy of 0.0147 g/cm3 in shale-free formations, and 0.0182 g/cm3 in shales, to be compared to the accuracy of traditional Gamma-Gamma density measurements (0.015 g/cm3).
Neutron-Gamma density uses inputs from all four detectors in an effort to set apartCompton scattering effects needed to calculatebulk density. Consequently, the spine-and-rib correction technique is not implemented in real time, leaving the measurement vulnerable to borehole environmental effects and mainly standoff. Standoff should be limited to 0.25 in for light mud, leading to a 0.05 g/cm3 correction ofbulk density. While the vertical resolution of Gamma-Gamma density is approximately 1 ft, results obtained from synthetic cases show that the vertical resolution of Neutron-Gamma density is limited to 2.5 ft. The vertical resolution of Neutron-Gamma density competes against improved depth of investigation. Neutron-Gamma density is less affected by invasion than Gamma-Gamma density. Depth of investigation of Neutron-Gamma density is approximately 9.5 in, i.e. twice as long as the depth of investigation of Gamma-Gamma density (~4 in). The main technical challenge of Neutron-Gamma density is measurement reliability across diverse solid and fluid rock compositions. Synthetic examples show that the tool design accurately resolves formation density in shale and shaly formations, high-density formations such as anhydrite, and formations saturated with low-density gas. In these cases, the accuracy is similar to that of Gamma-Gamma density and the measurement remains reliable for porosity estimates within +/- 1 pu.
We introduce a new tool design for a radioisotope-free, in-situ measurement of bulk density based on two-particle transport. This optimized tool design is the first one to provide an accuracy that compares to Gamma-Gamma density in clean and shaly formations. Synthetic cases serve to compare the measurements and provide insight about the conditions when Neutron-Gamma density can be used as an alternative to Gamma-Gamma density while achieving equivalent accuracy and performance.
The Changing Shape of Petroleum Engineering Education
Authors: Ershaghi Iraj , Paul Donald L. 
Published: October 2017

Abstract
In this paper, the focus is on the changes happening in the oil industry and the evolution of new tools and technologies transferred from other fields aiming to make the industry, more efficient and more acceptable to the consumer base. The discussion about the changing trends in petroleum engineering education is primarily focused on the U. S. producers. But some of the observations may equally apply to other national oil producers.
Currently and for the foreseeable future, oil and gas will continue to be the world's primary energy feedstock. This means that petroleum assets are as critical as they have been during the last century to meet the energy demands globally. If the industry continues its mission in providing oil and natural gas resources to the world communities, it will need the services of appropriately skilled professionals. Oil industry hires many technical professionals. At the core, however, there are unique petroleum engineering concepts and domain knowledge that defines the industry and its technology base. It probably fits better in describing the sciences and techniques as a broader base of subsurface engineering1 rather than energy engineering. This particular domain expertise can be gained in depth via formal university degrees or summarily through continuing education courses and augmented with on the job training.
The oil industry is changing, and parallel to that, are the expanded core competencies needed to take new directions. Some major emphasis areas affecting the shape of petroleum engineering education include technology transfer from the fields of information sciences, medical imaging, and human factor engineering. These all influence the core educational preparation of the petroleum engineering professionals. We discuss the history of PTE (petroleum engineering) education and the evolution of the industry and its manpower needs. As an example, we consider the petroleum engineering program at USC and review how, in response to the changing trends in the oil and gas operations, engagement with the industry has been helpful in opening new directions and changes in the academic educational content offered to the graduates. Utilizing case studies and experiences from the USC program, we illustrate the larger trends which have wider application to the industry and to changing the shape of university petroleum education programs.
Impact of Conveyance System on Reservoir Characterization: New Opportunity for Highly Deviated Wells
Authors: Raffaele V. , Pampuri F. , Terzuoli S. , Santo A. , French D. , De Clemente A. , Ciulli L. , Rinaldi R. 
Published: October 2017

Abstract
The recent trend toward drilling horizontal wells with complicated geometries in complex reservoirs has led to operational challenges. While LWD logs are often well suited in these environments, circumstances such as very small wellbores, tool availability, and high costs sometimes lead to a search for alternative means of acquiring a full suite of formation evaluation data.
The objective of this paper is to show how, in a very complex reservoir, the choice of conveyance system can be strategic, particularly in the context of data quality and risk mitigation.
The conveyance system considered is comprised of wireline tools which are housed inside drill pipe. When the borehole assembly reaches the toe of the lateral, a dart is pumped down, which releases the formation evaluation assembly and turns on the data acquisition. As the pipe is tripped out of the hole, the tools acquire data in memory.
The presented case study considers a field in Southern Europe where a fractured carbonate reservoir is developed with horizontal wells. Characteristics of the reservoir are very high resistivity, wellbore stability issues, presence of asphaltenes, and 6″ bit sizes. To fully characterize the reservoir properties and understand the natural fracture networks, electrical imaging, gamma-ray, dipole sonic and caliper data were acquired.
The integration of the dipole sonic and electric image logs provided the basic information to perform the matrix and the fractures evaluation as well as the anisotropy orientation and the best fluid path characterization. The availability of mechanical caliper led the decrease of the uncertainty in the interpretation and the optimization of the lower completion placement.
A comparison between LWD and WL image logs is presented to rate the real added value of the wireline acquisition.
This new approach using an alternative conveyance system enabled proper reservoir characterization. In addition to the high quality of the results there was also a reduced exposure to potential risks including stuck and lost in hole tools. The general pros and cons as well as cost considerations are discussed.
While the conveyance system is generally considered a drilling focused solution and is therefore most influenced by operational challenges, it should also be considered an additional resource for the petrophysicist and geologist performing essential data interpretation as proven by the presented case study.
Sequence Stratigraphy and Sedimentary Environment Identification Based on Palynological Analysis
Authors: Gao Y. , Liu Z. , Liu S. , Luo H. , Zhang W. , Zhu Y. , Tian C. 
Published: October 2017

Abstract
The subsurface identification of sequence stratigraphy and sedimentary environment commonly has a high uncertainty due to the ambiguity, low-resolution, or discontinuity of seismic data, wire log data, core description data or outcrop data. However, palynology can provide a relatively precise paleoecological and paleoenvironmental results and thus can be used as an explicit lateral correlation indicator for geologists. This paper shows a sequence stratigraphy and sedimentary environment determination case primarily based on palynology for the Upper Main Pay Member in Rumaila oilfield in Iraq.
640 samples in 8 wells were analyzed and grouped which occupied 93 palynological spices. They were clustered into 6 groups, including terrestrial algal group, arid terrestrial taxa group, wetland terrestrial taxa group, least marine dinocyst (dinoflagellate cyst) group, medium marine dinocyst group and most marine dinocyst group. The vertical and lateral changes and its rules of total counts and diversities for each group were studied after appropriate statistics based on their similarities and facies intervals.
The distribution and variation of each groups from bottom to top and from proximal-source to distal-source showed some interesting and regular trends which could be associated to the results of sequence stratigraphy evolution and sedimentary environment switch. The arid terrestrial taxa group was a good indicator of the distance from the sea and of the transgressive process, which implied a continuous transgression process in the study area. The wane and wax among the least marine, medium marine and most marine dinocyst groups manifested a relatively variable salinity paleoenvironment. The simultaneous occurrence of peak total counts of the least marine dinocyst group and terrestrial algal group, combining with the relatively low total counts of the arid terrestrial taxa group, suggested a barrier island paleoenvironment. In total, the variety of the palynology in lateral and vertical dimensions recommended a transformation environment from delta to estuary, which is very difficult to be determined by other kinds of data. After the reconstruction of sedimentary environment, the influential factors, the sources (allogenic or authigenic) and the transportation processes about the terrestrialalgae, spores and pollen, and dinocysts were studied, integrated with energy distribution of estuary model.
The grouping and interval samples summing statistics of palynological spices showed perfect assistances and verifications for the sequence stratigraphy determination and sedimentary environment identification. This could be helpful for lowering the uncertainty of geological studies, especially for the complex and ambiguous formations.
New Applications of Multidetector Pulsed Neutron Technologies in Gravel Pack Completions
Authors: Han Xiaogang , Scott Manasi , Schoepf Virginie , Mousavi Maryam , Stewart Carlos , Zett Adrian 
Published: October 2017

Abstract
Gravel Pack (GP) and Frac Pack (FP) are common sand control completion designs. There are various well known methods to evaluate effectiveness of gravel placement in the screen - casing annulus, allowing top of pack detection, void location and gross pack quality assurance. The increasing trend in using Non Radiation Traceable (NRT) proppant in both open and cased hole completions assists the evaluation of pack quality when using pulsed neutron logging technologies. Unlike traditional GP and FP evaluation techniques, Multi-detector Pulsed Neutron (MDPN) instrumentation provides a broader suite of nuclear attributes that can be used both qualitatively and quantitatively. Moreover, MDPN data can provide a baseline fluid saturation as has been widely documented.
Multiple datasets obtained from yard tests and two observation wells have been used to benchmark theoretical models based on multiple tool response equations. MDPN time lapse data and other static and dynamic log data will be discussed to emphasize the value of NRT proppant and MDPN surveillance during well life. The complexity of the logging environment means that a huge amount of rigor is required in the areas of job planning and execution in order to ensure the resultant dataset is optimized for use quantitatively. It is possible to generate a GP Quality Index scaled from 0% (no pack) to 100% (perfect pack) using one or more nuclear attributes depending upon the environmental conditions.
This paper will describe the advantages and disadvantages of each of the conventional GP evaluation techniques based on datasets from both yard test and live wells.
For NRT / MDPN applications, the processed nuclear attributes resulting from the NRT/MDPN GP evaluation show reduced uncertainty when compared with the conventional logging techniques. Using MDPN for GP evaluation also means this data can be used for other reservoir and well surveillance applications.
In-Situ Estimation of Relative Permeability and Capillary Pressure from the Joint Inversion of Array Resistivity and Formation Test Data
Authors: Liang Lin , Zhu Jianmin , Wang Fan , Chen Jie , Habashy Tarek M. , Abubakar Aria 
Published: October 2017

Abstract
We present an approach for estimating in-situ relative permeability and capillary pressure through the joint inversion of array resistivity logging and formation test data. Considering a scenario of drilling a vertical well into an oil-bearing formation with water-based mud, the mud-filtrate invasion process can be regarded as a controlled experiment under reservoir conditions. Array resistivity logging can sense the formation resistivity perturbed by the two-phase flow invasion. Formation testing with fluid sampling can also provide information on the radially varying saturation and the associated changes in mobility, as well as information on the effect of capillary pressure. A facies-based workflow is developed to invert for the relative permeability and capillary pressure from the abovementioned two data sets. The inversion strategy is adjustable based on a sensitivity analysis as well as on the data available and the operational sequence of collecting the data. A hybrid inversion framework combining deterministic and stochastic optimization approaches is developed for the inversion of the data.
FracBot Technology for Mapping Hydraulic Fractures
Authors: Al-Shehri Abdallah A. , Akyildiz Ian F. , Servin Jesus M. , Schmidt Howard K. 
Published: October 2017

Abstract
Miniaturized transponder systems for mapping hydraulic fractures, monitoring unconventional reservoirs and measuring other wellbore parameters are under development. These devices, called FracBots (Fracture Robots), are envisioned as an extension of RFID (Radio Frequency IDentifcation) tags to realize Wireless Underground Sensor Networks (WUSNs) for mapping and characterization of hydraulic fractures in unconventional reservoirs. When injected during hydraulic fracturing operations, autonomous localization algorithms could be used to build up 3D constellation maps of proppant bed placement. To explore this concept, a FracBot prototype platform was developed, with which three key functions have been demonstrated, and are here reported. First, we developed a novel cross-layer communication framework for Magnetic Induction (MI) -based FracBot networks in dynamically changing underground environments, combining joint selection of modulation, channel coding and power control, a transmitter-based CDMA scheme and a geographic forwarding paradigm. Second, we developed a novel MI-based localization framework which exploits the unique properties of the MI field to determine the locations of the randomly deployed FracBot nodes. Third, we developed an accurate energy model framework for a linear FracBot network topology that gives feasible FracBots' transmission rates and FracBot network topology while respecting harvested energy constraints. Future work will include design and fabrication of miniaturized MI-based FracBot nodes for evaluation in a physical WUSN testbed.
Laboratory Evaluation of a Natural Gas–Based Foamed Fracturing Fluid
Authors: Beck Griffin , Nolen Craig , Hoopes Kevin , Krouse Charles , Poerner Melissa , Phatak Alhad , Verma Sandeep 
Published: October 2017

Abstract
Foams have been used as hydraulic fracturing fluids to reduce water usage and minimize the potentially deleterious impact on water-sensitive formations. Traditionally, carbon dioxide (CO2) and nitrogen (N2) have been used as the internal phase in these foamed fluids. Hydraulic fracturing with natural gas (NG) is a relatively inexpensive option, particularly if NG produced from the wellhead can be used without significant processing. In an ongoing program sponsored by the US Department of Energy (DOE), an alternative fracturing process is being developed that uses NG-based foam. Previously, the optimal thermodynamic pathway was identified to transform wellhead NG into pressurized NG suitable for use as the internal phase in a foamed fracturing fluid. Recent work has focused on preparing a NG-based foam at surface conditions typically encountered in hydraulic fracturing and measuring the stability and rheological properties of the foam. In addition, the transient response of the foam during fracture initiation was simulated using a fast-acting solenoid valve. A single base-fluid mixture was prepared by combining a commercially available viscosifier and foaming surfactant with water. The base fluid was then injected into a tee using a water pump. Simultaneously, liquefied natural gas (LNG) was pressurized using a cryogenic pump, vaporized using a heat exchanger, and injected into the tee to mix with the base fluid and generate foam. The foam then flowed through approximately 300 ft of 0.312-in. inside diameter (ID) tubing equipped with pressure transducers at several locations. The test fixture included a sight glass to visually inspect the quality of the foam. This paper reports on findings related to foam stability and rheology and compares these results to previous studies on foamed fracturing fluids.
Members in Transition: Career Planning, Job Search, Entrepreneurship and Innovation
Authors: Howes C. Susan , Hite J. Roger , Clute-Melancon Daniel De 
Published: October 2017

Abstract
The Members in Transition (MiT) initiative was established by the Society of Petroleum Engineers (SPE) Gulf Coast Section (GCS) in response to the downturn in the industry. Career transition can be defined both as a category for members who are waiting to land a job, and those who are employed, but looking to transfer their skills to other sectors of the oil and gas industry. The function of the MiT initiative is to disseminate best practices in career planning, job search, entrepreneurship and innovation. MiT events allow those in transition to feel the support of their colleagues in the Society and create opportunities for reciprocity where one can help one's colleagues. MiT activities provide learning opportunities to enable participants to rethink fundamental strategies and to find new ways to survive the downturn conditions.
The SPE-GCS has prepared a process guide to help other SPE sections to set up their own local MiT initiatives. The SPE-GCS MiT initiative includes:
A monthly seminar series Access to free computer software licenses and training Ideas Launch Pad, a relationship with the Houston Technology Center to encourage entrepreneurship Pay-it-Forward Networking Tours, Training and Panels Job Search Work Team, small groups who meet weekly to work on their job searches together, a concept based on Orville Pierson's books on job search. A career fair heldregularly
Starting in early 2016, the first five methods listed above have been deployed with strong participation. The sixth method, the career fair, was initiated in 2017. While a MiT survey was used to collect demographics and feedback, the more useful measure of the success of this initiative will be how many SPE members return to an employed state in the energy industry after spending time in transition. The downturn has caused several members to consider entrepreneurship and innovative business schemes as a replacement for fulltime employment. Disruptions cause people to rethink their standard processes, or way of doing things, and look for ways to do them more effectively and efficiently. This focus on entrepreneurship and innovation will continue to provide value to members, even after the downturn ends.
The SPE-GCS collaborates with other technical and professional societies to provide resources for members in transition. SPE-GCS partners with the Houston Technology Center (HTC), the largest technology business incubator and accelerator in Texas, advancing the commercialization of emerging technology companies in the greater Houston area. The MiT initiative launched by the GCS has been complementary to the support that SPEI provides globally via the MiT toolkit and Journal of Petroleum Technology (JPT) articles profiling perspectives of SPE technical directors and leaders.
A Robust Model to Estimate the Mud Loss into Naturally Fractured Formations
Authors: Bychina Mariia , Thomas Gevargis M. , Khandelwal Ravi , Samuel Robello 
Published: October 2017

Abstract
Drilling through naturally fractured formations results in multiple complications; fracture ballooning and loss circulation are predominant among them that requires more understanding of the process. In order to better understand the mechanism behind fluid loss into the natural fractures a new model has been developed which addresses the shortcomings of pre-existing models.
The paper presents a new comprehensive analytical model; represented by partial differential equation that can be used for various fluid rheologies and thus, eliminating the need for different models for different fluids. The model also takes into consideration of fracture deformation with constant and variable leak off rates into the formation. The proposed model was validated by reducing it to the preexisting models by incorporating their assumptions into it. The model has also been validated using synthetic as well as multiple field data. Sensitivity analyses were performed to determine the effects of fracture normal stiffness, leak off rate, mud-yield stress, aperture and other parameters on fluid losses. The new model presented demonstrates that fracture deformation and leak off pressure play important roles in the determination of fluid loss into the formation. The results have shown that by neglecting the fracture deformation or leak off results in the under estimation of fluid losses. It has also been found that the fluid Yield stress plays an important role in preventing fluid loss into the formation. Sensitivity analysis shows that once the pressure potential falls below the yield stress value, the fluid migration into the fracture is stopped.
The novelty of the proposed model lies in the fact that it can be used for different drilling fluids and also more generic. It takes into account fracture deformation and leak-off into the formation which lead to more accurate estimation of fluid losses than the existing models.