bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Trouble Stages with Geomechanical Measurements and Machine Learning: A Case Study on Southern Midland Basin Horizontal Completions
Authors: Romberg Eric , Fisher Aaron , Mazza Joel , Niedz Chris , Wehner Brian , Zhou Alex 
Published: October 2020

Abstract
Unexpected problems during completion create costs that can cause a well to be outside its planned AFE and even uneconomic. These problems range from merely experiencing abnormally high pressures during treatment to casing failures. The authors of this paper use machine learning methods combined with geomechanical, wellbore trajectory, and completion datasets to develop models that predict which stages will experience difficulties during completion.
The operator collected geomechanical data for 26 lateral wells. Several of these wells experienced significant difficulties during completion, including casing failures. By examining the completion data for the study wells, engineers developed two objective proxies for trouble stages: a high fracture gradient cut-off and a sand-to-water ratio cut off. The geomechanical data were combined with wellbore trajectory and stage-level completion data. Machine learning techniques were then used to predict the fracture gradient at the end of treatment and the sand-to-water ratio of a stage. The data were subdivided by target horizon to ensure the model results were not skewed towards a specific horizon. The models were cross validated, hyper-parameter tuned, and then tested against a subset of the data withheld from the training algorithm (the test data subset).
Multiple metrics were applied to measure the effectiveness of the models. For the fracture gradient regression, the model that minimized the root mean squared error (RMSE) was chosen. This model was compared to a prediction that each stage would have a fracture gradient equal to the average fracture gradient. The correlation between predicted and measured frac gradients was also calculated. These metrics were analyzed for both the entire data set and the test data subset. By all these measures the model performs significantly better than the control prediction. For the sand-to-water ratio metric, the model that maximized the receiver operating characteristic area under the curve (ROC-AUC or AUC) score was chosen. We chose to measure the success of the model with the precision of its prediction of outlier (trouble) stages on the test data subset. The model performs with a precision of at least 73%. Both models identify stages where casing failures occurred as trouble stages. With these initial results, the authors are confident they can predict the probability of any stage causing a significant operational disruption in these horizons.
By predicting the probability of a trouble stage, mitigation plans can be implemented to reduce costs ahead of time. By further analyzing the models, engineers can identify the major drivers for the trouble stages and work to reduce them as early as the well planning stage.
An Integrated Equation-of-State Compositional Hydraulic Fracturing and Reservoir Simulator
Authors: Zheng Shuang , Sharma Mukul 
Published: October 2020

Abstract
In this paper, we present an integrated equation-of-state based compositional hydraulic fracturing and reservoir simulator. The goal of this research is to develop a general simulator that can simulate the lifecycle of wells, which includes hydraulic fracturing treatment using water-based or energized fracturing fluid, post-frac shut-in and flowback with fracture closure and proppant settling, primary production with proppant embedment and fluid reinjection in a multiple well pad.
This simulator fully couples the reservoir, fracture, and wellbore domains with multiple physics in each domain. The rock deformation, porous flow and temperature change in the reservoir domain, fluid and proppant transport in the fracture domain, and wellbore slurry flow and fluid/proppant distribution among clusters are fully coupled together and solved fully implicitly using the Newton-Raphson method. The phase behavior of hydrocarbon phases is modeled using Peng-Robinson Equation-of-state. The fracture propagation is modeled by mesh topology change (dynamic remeshing and local refinement) and the propagation direction is evaluated using the stress intensity factors. This simulator has been fully parallelized using MPI. We show two applications of this simulator for lifecycle analysis in US unconventional oil reservoirs on frac-hits and CO2 fracturing.
In the first field application, we simulate a multi-well fracture diagnostics. We used the parent well to monitor the child well fracture growth. Child well fracture growth is correctly interpreted using the monitoring data. In the second field application, we perform lifecycle analysis of hydraulic fracturing treatment using hybrid CO2-slick water-crosslinked gel fracturing fluids and 100/30-50 mesh proppants and the following production phase from a well in the Bakken formation. We successfully match the complex surface treating pressure data from the field. We also successfully matched the cumulative production of oil, gas and water and explained the long-term CO2 flowback phenomenon in the field.
The novelty of this simulator comes from its unique modeling capability in the well lifecycle analysis. Fully coupled reservoir-fracture-wellbore framework allows accurate modeling of hydraulic fracture propagation in multiple well pads using multiple fracturing fluids and proppants, fracture closure during shut-in, primary production, refracturing, and pre-loading for parent well protection, and huff-n-puff improved oil recovery, all in one simulation. This simulator can be used as a reliable and efficient tool by operators in well lifecycle analysis.
A Modified Acid System to Enhance Carbonate Matrix Acid Stimulation – An Experimental Study
Authors: Zhu Ding , Uribe Julian , Sohn Daniel , Hill Dan , Ugursal Assiya , Shuchart Chris , Purdy Clay , Weissenberger Marcus 
Published: October 2020

Abstract
In carbonate matrix acidizing, the critical design parameters are interstitial velocity and pore volume to breakthrough for wormhole propagation at the optimal condition (vi,opt and PVBT,opt). These two parameters are determined by the formation rock properties including permeability, porosity, temperature, pressure, and mineralogy, and the acid system that will be used. HCl has been the most commonly used acid in carbonate acidizing. However, the efficiency of wormhole creation using strong HCl solutions is sometimes low because the injection rate needed for optimal wormhole propagation is not attainable, especially when applied to long completion intervals and/or low permeability carbonates. High concentration HCl solutions also raise safety and environmental concerns. When retarded acid systems are used to overcome these challenges, the efficiency of acid stimulation often suffers from low reaction rate and low dissolving power. This study presents testing results of a modified acid system that has controlled reaction rate with favorable wormhole propagation characteristics, especially at low interstitial velocities.
Due to the increased activation energy barriers utilized in these modified-acid systems, it is possible to control the reaction rate of the hydrogen proton and optimize the wormholing effect based on the completion method and formation specifications. Single phase modified acid systems are applicable and can be tailored for limestone and chalk formations. Laboratory linear core flooding experiments and acid jetting experiments were conducted to study the wormhole efficiency with the new acid systems. Core flood tests were designed to generate the wormhole efficiency curves and compare the results from the tests with HCl under the same conditions. Jetting experiments were conducted to evaluate the structure of cavity and wormhole development, and the results were also compared with HCl injection at similar conditions. Results from the experimental study were then used to compare the acid systems through wormhole efficiency curves and CT scans of acid dissolution structures.
The experimental results showed clear advantages of the modified acid systems. The modified acids have similar or better wormhole efficiency parameters compared with HCl having comparable dissolving power. When combined with acid jetting, further improvement in wormhole growth in low permeability limestone is achieved. In addition to minimizing the hazardous exposure levels, corrosion rates, and negative HS&E properties compared with hydrochloric acid, the new acid system provides the positive aspects of solubilizing ability and reaction rates thus improving optimal wormhole conditions (lower vi,opt and PVBT,opt). This potentially allows for better stimulation results with less fluid required.
Design of a Fiber Optic Based Wellhead Perimeter Monitoring System
Authors: Idachaba Francis 
Published: October 2020

Abstract
The advent of Digital Oil Fields (DOF), Data Analytics and Artificial Intelligence has led to an increase in the number of instruments installed at wellheads and also an increase in the reliance on these instruments and the data they provide for the operation of the field. The critical nature of this equipment and their roles in the operation of the oil field has also led to the need for a system of remote monitoring of these wellheads to enable the detection of third-party intrusion (TPI) at the wellhead area with the provision of video feedback on demand. The most popular security scheme currently deployed at securing these wellheads is the use of metal cages of different sizes, but the location of these wellheads provides vandals with ample time to cut through the metal cages as there is no means of detecting their presence. This system utilizes a fiber optic cable and cameras to provide intruder detection and identification. It transmits the signals wirelessly through the remote telemetry units at the wellhead. The fiber optic cable is buried around the wellhead, and the flowlines from the wellhead and a wireless transmitter are coupled to the fiber optic cable. The distributed acoustic system of the optic fiber is used to detect the presence of third-party interference at the wellhead locations, and the camera is activated by the system whenever TPI is detected around the wellhead area. The system provides both video feedback and color-coded alerts at the remote monitoring centers to indicate the location of the intruders and the intrusion activity around the wellhead area.
Quantifying the Impacts of Stern and Diffuse Layer Polarization on Multi-Frequency Dielectric Permittivity and Electrical Conductivity of Rock-Fluid Systems
Authors: Posenato Garcia Artur , Heidari Zoya 
Published: October 2020

Abstract
A thorough understanding of the interplay between polarization mechanisms is crucial for interpretation of electrical measurements because sub-MHz electrical measurements in sedimentary rocks are dominated by interfacial polarization mechanisms. However, rock-physics models oversimplify pore-network geometry and the interaction of electric double layers (EDL) pertaining to adjacent grains. The impact of these simplifications on the assessment of petrophysical properties, such as hydrocarbon reserves, is difficult to quantify and often unknown. Numerical algorithms present the ideal framework to characterize the electrical response of sedimentary rocks, circumventing the limitations intrinsic to rock-physics models. Our recently developed algorithm simulates the interactions of electric fields with the ions in solution. However, a model for the polarization mechanism associated with the Stern layer has not been developed. The sub-kHz permittivity enhancement in sedimentary rocks is dominated by Stern layer polarization. Therefore, the objective of this paper is to develop a numerical simulation framework capable of quantifying the influence of Stern- and diffuse-layer polarization, temperature, ion concentration, and pore-network geometry on multi-frequency complex electrical measurements.
We developed a numerical simulator to compute time-dependent behavior of electric field, ion concentration, and interfacial polarization mechanisms in sedimentary rocks. The algorithm numerically solves the Poisson-Nernst-Planck (PNP) equations in the time domain conjointly with a mineral-dependent electrochemical adsorption/desorption equilibrium model. Then, we use the numerical simulator to perform a sensitivity analysis to quantify the influence of electrolyte and interfacial properties on the permittivity of pore-scale samples at different frequencies. Results demonstrated that the joint effect of Stern layer ion concentration and corresponding mobility dominates sub-MHz dielectric response of rocks. The low-frequency permittivity enhancement due to the EDL can sweep several orders of magnitude. The Stern layer polarization acts as a macroscopic (i.e., at the grain scale) dipole created by counterions wading around the surface of the grains due to an externally applied electric field. Therefore, the grain shape and corresponding orientation relative to the electric field significantly affect the behavior of macroscopic Stern layer dipoles. Reliable interpretation of multi-frequency electrical measurements can provide insights in mineralogy, fluid typing, grain size, and interfacial properties. Time-domain numerical modeling of complex permittivity dispersion can greatly enhance interpretation of multi-frequency dielectric measurements.
Using Data Analytics to Improve Drilling Rate of Penetration
Authors: Eade Jeremy 
Published: October 2020

Abstract
It takes an average of 7 days to drill through the Travis Peak formation in the southern Haynesville basin. The objective of this paper was to improve the rate of penetration (ROP) and therefore reduce the time taken to drill through this formation. Machine learning and regression models were applied to electronic drilling record data and identified that the auto-driller ROP setpoint was the most influential variable ROP for wells drilled in the Travis Peak formation. This finding was corroborated during field visits with well site leaders and drillers with the discovery that ROP was being used as the controlling setpoint in the auto-driller system for drilling in the Travis Peak and Calvin Sand formations.
After discussion with the rig provider, a new set of auto-driller parameters was proposed using weight on bit as the controlling setpoint with the objective of increasing the rate of penetration. The new auto-driller parameter roadmap was piloted on two wells.
ROP performance for these two wells was significantly better than the nearest offset and other offsets in the nearby area. The drilling team estimate about two days per well time saved as a result of the improved ROP.
Regenerative Practice for Oil and Gas
Authors: Moon Flora 
Published: October 2020

Abstract
While the industry is actively looking to increase efficiency, mitigate and remediate outcomes of extractive practices, there is a shift in requirement for the license to operate – from sustainability (balancing harm) to regeneration (giving more than taking). The sustainability phase continuum can be described as making moves from recycling to sustainability to regeneration. Movement through the phases may be thought of in terms of doing less harm to the planet (everything in it and on it) to giving more than taking from the planet. By mapping activities to specific phases, a representative picture of key current and potential areas/technologies for regenerative industry practice could provide mechanisms and strategies for evolving sustainability/regenerative enterprise strategies. The key takeaway: Improving resource efficiency efforts through nature-based solutions and regeneration of social and environmental conditions will materially increase positive impacts including lower carbon footprints.
Geomechanical Well Testing: A New Methodology for Interpretation of Pressure Transient Testing Data for Geomechanical Applications
Authors: Rafieepour Saeed , Baldino Silvio , Miska Stefan , Ozbayoglu Evren , Zhang Jianguo 
Published: October 2020

Abstract
Rock mechanics triaxial tests and well logs are the main source for determination of mechanical properties of reservoir. These methods obtain values for mechanical properties corresponding to parts of the formation close to the well area. The experimental approach is much more limited as the coring operation is costly and is performed in a handful of appraisal/exploratory wells. Here, a novel methodology, geomechanical well testing, is presented to estimate the elastic and plastic mechanical properties using pressure transient testing. In the first part of the paper, the theory of poroelasticity was utilized to develop a geomechanical well testing technique, which attains estimation of reservoir's poroelastic properties. The technique is on the basis of developing a diffusivity equation incorporating mechanical deformation into the fluid transport in porous media and via applying different mechanical boundary conditions, one can obtain several closed-form solutions for storage coefficient. The developed storage coefficients, however, include Poisson's ratio (PR) as the target variable to estimate from conventional well testing. As a verification, a case study was conducted using the pressure transient data from a sandstone aquifer. Adopting the conventional well testing principles, three different values for PR were obtained. The first impression to this point was to decide which value is the most representing value for the aquifer under investigation. We envisioned two methods for this critical step: 1) comparison of obtained PR values from the geomechanical well testing technique with the one estimated via another reliable source such as well log/seismic and/or 2) comparison of pressure-time measurements with available numerical simulations. We took this finding for granted and devise a way to obtain an estimation of dominant boundary conditions of a reservoir. Once the dominant deformational behavior was assessed, the technique may be re-implemented along with future well testing measuements to monitor the evolutions of elastic properties during the life of reservoir. The second part of the paper deals with another geomechanical well testing technique, which provides a tool for estimation of strength properies through developing a generalized diffusivity equation using poroplasticity theory with a plastic potential function based on Mohr-Coulomb yield/failure criterion. An analytical solution was obtained under uniaxial strain assumption, which can be used to estimate internal friction angle or dilation angle.
Investigating Deposition of Nanocatalysts in Porous Media for Catalytic Downhole Upgrading Processes
Authors: Khoshooei Milad Ahmadi 
Published: October 2020

Abstract
A recently proposed in-reservoir upgrading method, called In-Situ Upgrading Technology (ISUT) integrates both downhole upgrading and recovery enhancement in one single process. This method employs catalytic nanoparticles of nickel and molybdenum (NiMo) which are dispersed in vacuum residue (VR), the lowest quality fraction of oil. The dispersed nanocatalyst in VR along with hydrogen are then injected in the reservoir to carry out hydroprocessing reactions. The upgraded liquid and produced gases displace the oil-in-place towards the production well. Therefore, it is important to investigate the deposition of nanoparticles and the correlation with the injected hydrocarbon molecules in porous medium.
In this study, a continuous setup was designed and constructed to investigate the deposition of nanoparticles in a sandpack that mimics the oilsand reservoirs. The VR containing nanocatalysts was injected to decorate the sandpack with catalyst. The operating conditions were set to 350 °C, 1000 psig (7 MPag) and 48 hr of residence time. Once certain concentration of catalyst was deposited in the sandpack, the process was stopped and the sandpack was taken and cut in ten sections for analysis. A comprehensive post-mortem analysis including investigation of catalytic particle deposition as well as characterization of the entrapped hydrocarbons in each segment was carried out.
It was already observed that the particles irreversibly and totally retain in the porous medium in ISUT process. In this work, an attempt to correlate the deposition of catalyst mechanism with the hydrocarbons that might help the deposition process was performed. It is assumed that the polar components, mainly asphaltenes, play a key role in carrying the catalytic particles and allow them to deposit. Several implicit and explicit analysis were performed to investigate this assumption in this work. Results showed that the sections containing the highest concentration of catalyst contain heavier molecules such as asphaltenes.
Digital Oil Field: Real Time pH Monitoring and Automatic Neutralization System Using Smart Phone/Watch/PC and Microcontroller in Hydrogen Sulfide Formations
Authors: Alhandhal Hussein Basim 
Published: October 2020

Abstract
In the last decade, the oil and gas industry has been extended in direction of Digital Oilfield (DOF) approaches (i.e. using smart phone/watch, historians and data management) in many fields such as drilling and health-safety-environment, to improve efficiency and reduce cost. DOF helps in real-time data transfer, monitoring, data cleaning and processing, interpretation, and visualization to make an optimal decision. Moreover, the DOF system has an ability to self-learning via feeding the labeled historical data to update the entire model.
Monitoring, surveillance, diagnostic and modeling management can be made by a person(s) observing the job remotely, rather than locally, with potential for significant cost savings by cooperating various experts to data analysis. Also, real-time system creates continuous well performance monitoring system, thus the system provided a platform for better understanding of the effects of the reservoir behavior which could be reflected on optimizing production operations and enhanced health, safety and environment.
In this project, a controlling system is used to maintain and treat pH of drilling mud, as well as using smart devices to monitor the data at real time. This paper describes a lab-scale flow loop drilling system with real-time monitoring and treatment systems for mud H2S contamination control. The readings of the pH level, electrical conductivity, and pH neutralization chemical valve opening are real-time monitored and control remotely via Internet by using a smart phone to view the streamed data to authorized person as trends for each parameter/sensor.
The results show, the proposed system monitors the streamed data for detectable events and triggers automated notifications to personnel who are ‘following’ the job. In this manner, an operator can be alerted when the H2S is indicated by a significant change in EC accompanied by decreasing pH, an automatic mud treatment control system, and monitored by the smart devices, activates to restore and maintain a targeted pH value.
The presence of H2S in hydrogen sulfide bearing formations introduces significant risks due to its extreme toxicity and its corrosive effects on drilling rig equipment. To ensure protection of drilling operation personnel, a real-time pH/EC monitoring system is developed using a remote and smart control unit that could send alerts and control the treatment process while simulating and monitoring H2S influx on smart phone and smart watch.
This project demonstrates the usage of an edge technology in petroleum industry that meets future aspirations of oil and gas industry, which is represented by the self-learning system that could improve the results and increase its accuracy by using the continuous feed of data to the system database.