bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying Well Integrity Risk at Scale: A Repeatable & Data Driven Analysis of Well Integrity in Unconventional Gas Fields
Authors: Thomas T. J. , Norman B. J.
Published: October 2023

This paper presents the results of a well integrity research project conducted on 1,605 unconventional gas wells in Queensland Australia, and discusses the methodology employed which can be applied to other fields. This paper focuses on the methodology used by the research team, which had been termed ‘barrier logic’, a set of standardized questions, exemplar answers and numerical values assigned to each of the answers which is than scored against an industry standard Risk Assessment Matrix. This methodology was used to assess all the wells in the selected fields, and provided the operating company that manages them an up-to-date and consistent risk scoring for their entire well stock. The methodology developed during this research provides several benefits to well operators, such as: reducing the level of individual bias and error based on multiple employes scoring risks, streamlines decision making on remediation work, as risk scoring has been reviewed and agreed in advance and providing a more accurate assessment of individual wells’ integrity based on the construction and operation activities being individually assessed. Many operators would share the same benefits of applying this, or a similar methodology to their well stock and several key insights and recommendations for others are provided at the end of this paper.

The use of large data analytics, machine learning and broader AI for predictive analysis, especially for production optimization and completion failure forecasting, is a rapidly growing field of expertise in Oil and Gas. For example, there are over 50 conference papers and journal articles registered on SPE's OnePetro that contain the term ‘Machine Learning’ in their title for 2023 alone. This paper adds to this growing body of research, showing the benefits to operating companies when data centric analysis and the digitization of data and processes is applied.
Reviving of Gas Well Using the Mobile Wellhead Gas Compressor Technology
Authors: Alhajri F. M. , Samsudin Z.
Published: October 2023

Reviving "ceased to flow" wells no longer has to be a complicated procedure. The Mobile Wellhead Compressor (MWHC) technology has a compact design of gas and liquid handling systems, suitable for reviving wells and boost the gas production as an alternative to the conventional Coiled Tubing Nitrogen Lifting (CTNL). The objective of this paper is to present the findings obtained from a thorough engineering evaluation of trial testing the MWHC technology in a gas well.

The MWHC technology was deployed to revive a ceased to flow gas well due to liquid loading as a result of flowing below the required velocity. The production enhancement by lowering system back pressure was the best solution to revive the well and unload the associated liquid in order for the well to be able to join the production trunk line.

As for the trial test results, the mobile wellhead gas compressor performed well within its design parameters. The unit successfully managed to reduce the wellhead pressure to atmospheric pressure during the well revival and handled the produced fluids (Gas & Liquids) during the flow regime, leading to easy well reviving and liquid unloading. Post-trial, well parameters were found healthy and satisfactory along with achieving the trial objective of making the well alive and bringing it back into production with no further need for compression equipment. The performance of the system was very remarkable as the well was revived in less than 13 hours, which is an excellent promising result compared to the CTNL 7-14 days duration. Therefore, the mobile wellhead compressor was deemed an acceptable cost-effective alternative to CTNL.

In summary, the MWHC technology with such service, size and features is very unique whereby combination of different types of compressors and liquid pump are packaged together along with the proprietary control system. The mobility advantage of the compressor will allow quick and easy movement to cover a wide range of wells. In addition, the technology is a cost-effective solution compared to the conventional CTNL.
Accurate Prediction of the Saturation Pressures of Hydrocarbons in Unconventional Reservoirs: A Modified Alpha-Function for the Peng-Robinson Equation of State
Authors: Lin Lixing , Babadagli Tayfun , Li Huazhou Andy
Published: October 2023

Due to the confinement and strong adsorption to the pore wall in meso- and nano- pores, fluid phase behavior in the confined media, such as the tight and shale reservoirs, can be significantly different from that in the bulk phase. A large amount of work has been done on the theoretical modeling of the phase behavior of hydrocarbons in the confined media. However, there are still inconsistencies in the theoretical models developed and validations of those models against experimental data are inadequate.

In this study, we conducted a comprehensive review of experimental work on the phase behavior of hydrocarbons under confinement and analyzed various theoretical phase-behavior models. Emphasis was given to the modifications to the Peng-Robinson equation of state (PR EoS). Through the comparative analysis, we developed a modified alpha-function in PR EoS for accurate prediction of the saturation pressures of hydrocarbons in porous media. This modified alpha-function accounts for the pore size and was derived based on the regression results through minimizing the deviation between the experimentally measured and numerically calculated saturation pressure data. Meanwhile, the thermodynamic properties of propane were calculated in the bulk phase and in the nanopores. Finally, we validated the newly developed model using the experimental data generated within our research group.

By applying the modified PR EoS, a more accurate representation of the experimentally measured saturation pressure data in confined nanopores was achieved. This newly developed model not only enhanced the accuracy of the predictions but also provided valuable insights into the confinement effects on the phase behavior of hydrocarbons in nanopores. Notably, we observed significant changes in the properties of propane within confined nanopores, including suppressed saturation pressure and fugacity, indicating a greater tendency for the gas to remain in the liquid phase. Additionally, the gas compressibility factor and enthalpy of vaporization were found to increase highlighting increased difficulty in transitioning from liquid to gas phase under confinement. To validate its applicability, the newly developed model was applied to the experimental data obtained in real rock samples. Interestingly, it was observed that the phase change in these samples predominantly occurred in the smallest pores. This finding highlights the importance of considering the pore size distribution when studying the phase behavior of hydrocarbons in a capillary medium even if the rock has high permeability.

This study provided a simple and easy-to-implement modification to the PR EoS for accurate prediction of the phase behavior of petroleum fluids under confinement. The modification to PR EoS was more straightforward and simplified compared to the modifications available in the literature.
Fracture Network Characterization Beyond Wellbores: A New Approach to Identify Water Corridors through Advanced Resistivity Analysis
Authors: Manuaba Ida Bagus Gede Hermawan , Aljishi Mohammad K , Santoso Gagok Imam , Dolan James T
Published: October 2023

Carbonate rocks are often characterized as containing complex porosity systems from primary to secondary, and even intertwined multi-porous systems. Consequently, this creates a challenge for petrophysicists and geologists with identifying the impact of such a complex system on wells’ productivity. This paper studies delineating fracture network proximity and architecture beyond the wellbore and successfully identifying water corridors for completion enhancement.

This paper presents a novel methodology for integrating wellbore-centric micro-electrical borehole imaging with an ultra-high-resolution bed boundary mapper (UHR-BBM). The approach integrates the quantification and categorization of fractures around the wellbore acquired through resistivity image, and fluid network in a radius of up to 30 ft around the wellbore derived from UHR-BBM. The process encompasses a workflow starting from invasion profile determination to UHR-BBM geo-signals enhancement with fracture details prior to ultimately mapping their network extension and fluid characterization. Advanced borehole analysis provided new insight into textural variations and litho-facies when analyzing fractured zone, opening a gateway to incorporating geological features into the petrophysical analysis. Accordingly, it was observed that fractures could contribute an additional percentage of secondary porosity, improving the productivity index of such formation. However, through conducting the aforementioned analysis, some of the fractures were featured as water-driving factors when their proximity beyond the wellbore was uncovered. Moreover, resistivity analysis concluded that the water-driving factors could have implications when the true resistivity affects the modeling process. Ultimately, the completion design shall be altered to isolate such zones, enhancing hydrocarbon recovery with minimized water cuts, as will be shown in one of the examples.

This methodology utilizes a new technique of incorporating shallow and deep measurements to quantify fracture systems, asses their proximity to the wellbore, and determine their potential impact on the well performance. This analysis facilitates a new approach to well completion design optimization, prolonging the life of the well and enhancing productivity.
Is Petroleum Engineering Curriculum Change Far from Academic?
Authors: Samuel Robello
Published: October 2023

The changing environment, demography of workforce and the advancements of technology require the urgency of the reforms needed in the petroleum engineering education and curriculum. Restructuring of the petroleum industry due to the protracted downturn is also aiding the accelerating pace of change. In alignment with the industry, the talent pipeline from the education system should also be in lockstep alignment. Curriculum changes are also required to take into consideration the topics and subjects related to sustainable energy sources as the world transitions to clean energy. This will help provide the students an opportunity to acquire interdisciplinary knowledge. Present-day education system must move away from the model of "learn at school" and "do at work" as the industry has moved away from "on the job" training or induction training. So, the petroleum engineering education must move to "learn and work" school model so that students are ready to take up the job from day one. The new approach should include basic engineering, advanced engineering and experiential learning that culminates to the required expertise to get assimilated in the workforce. The paper presents and addresses the scope and approach for a new curriculum for petroleum engineering education. This paper is an extended and repeat of text version of the paper SPE-206305-MS titled, "Petroleum Energy Engineering Education Reform: Flipping the Curriculum" paper presented at the SPE Annual Technical Conference and Exhibition, Dubai, UAE, September 2021 (Samuel 2021). This paper has an alternative solution and improves the theoretical framework of the course curriculum.
Best Practices in DFIT Interpretation - Comparative Analysis of 80 DFITs in the Canadian Montney Shale Play
Authors: Virues Claudio , Robertson Alexandra , Sendecki Bruce
Published: October 2023

Current practice for conducting minifrac or diagnostic fracture injection tests has been changing with time. The Alberta Energy Regulator (AER) has a pressure and deliverability testing directive that has guidance on those tests. This guidance was updated in late 2021. Many operators from the Canadian Montney shale play submit minifracs to AER, 80 of these minifracs were summarized statistically in this paper. Closure, reservoir pressure, and permeability were the main analyzed parameters in the paper scope.

Requirements for pressure and deliverability tests are set out by this newly updated directive. Industry uses minifrac in horizontal wells with multistage fracture treatments when developing unconventional reservoirs. Closure, initial reservoir pressure is commonly being determined with the common well test. Holistic or tangent vs. compliance method are compared for closure pressure in this paper. Readers are eager to replicate results, so for After Closure Analysis (ACA) methods equations that govern the analysis are provided in detail.

Published or commercially available holistic and compliance models are compared for closure pressure. Published or commercially available ACA Soliman and Nolte methods are compared for permeability and reservoir pressure. Horizontal wells in 80 unconventional shale field case studies are presented. The fact that the signature of closure pressure is not apparent is a significant finding. Similarity of closure pressure outcomes or estimates for tangent vs compliance is remarkable. Differentiation of reservoir pressure determination for either linear or radial flow are observed. Interpretation on net pressure impact is evaluated and ultimately differentiation on ACA permeability determination is assessed. Analogous shale plays operators in USA and current Canadian Montney Shale play operators will find practical and direct implications. To calculate effective fracture half length and optimize fracture design and well spacing accurate permeability values are needed. To design hydraulic fractures with geomechanics applications accurate closure pressure values are essential. To conduct Rate Transient Analysis (RTA) for resources and reserves assessment in similar unconventional shale plays accurate initial reservoir pressure as an input is fundamental.

Comparing analytically closure pressure methods in unconventional shale plays is novel. In addition, practicing engineers or well testing interpreters will find the comparison of different after closure analysis relevant.
Reducing NPT Using a Novel Approach to Real-Time Drilling Data Analysis
Authors: Wang Junzhe , Sajeev Shyam Kareepadath , Ozbayoglu Evren , Baldino Silvio , Liu Yaxin , Jing Haorong
Published: October 2023

Early detection and characterization of anomalous events during drilling operations are critical to avoid costly downtime and prevent hazardous events, such as a stuck pipe or a well control event. A key aspect of real-time drilling data analysis is the capability to make precise predictions of specific drilling parameters based on past time series information. The ideal models should be able to deal with multivariate time series and perform multi-step predictions. The recurrent neural network with a long short-term memory (LSTM) architecture is capable of the task, however, given that drilling is a long process with high data sampling frequency, LSTMs may face challenges with ultra-long-term memory. The transformer-based deep learning model has demonstrated its superior ability in natural language processing and time series analysis. The self-attention mechanism enables it to capture extremely long-term memory.

In this paper, transformer-based deep learning models have been developed and applied to real-time drilling data prediction. It comprises an encoder and decoder module, along with a multi-head attention module. The model takes in multivariate real-time drilling data as input and predicts a univariate parameter in advance for multiple time steps. The proposed model is applied to the Volve field data to predict real-time drilling parameters such as mud pit volume, surface torque, and standpipe pressure. The predicted results are observed and evaluated.

The predictions of the proposed models are in good agreement with the ground truth data. Four Transformer-based predictive models demonstrate their applicability to forecast real-time drilling data of different lengths. Transformer models utilizing non-stationary attention exhibit superior prediction accuracy in the context of drilling data prediction.

This study provides guidance on how to implement and apply transformer-based deep learning models applied to drilling data analysis tasks, with a specific focus on anomaly detection. When trained on dysfunction-free datasets, the proposed model can predict real-time drilling data with high precision, whereas when a downhole anomaly starts to build, the significant error in the prediction can be used as an alarm indicator. The model can consider extremely long-term memory and serve as the alternative algorithm to LSTM. Furthermore, this model can be extended to a wide range of sequence data prediction problems in the petroleum engineering discipline.
Liza Unity: Start-Up and First Year Operations
Authors: Verma Saurabh Kumar , Ramachandran Kartik
Published: October 2023

Guyana's oil and gas production commenced in December 2019 with the Liza Destiny floating production, storage, and offloading (FPSO) vessel for the first phase development of the Liza Field located in the south-eastern portion of Stabroek Block, offshore Guyana. Esso Exploration and Production Guyana Limited (EEPGL) achieved first oil on Liza Unity, the second FPSO in Guyana, in February 2022. A robust process of implementing lessons learned from Liza Destiny commissioning and start-up were adapted by the Liza Unity team. The Liza Unity FPSO is moored approximately 190 km offshore Guyana in 1600-1700 m of water depth. The FPSO is designed to develop the remaining portions of the Liza field, that were not targeted in first phase of development. The subsea system includes eight subsea manifolds (four production and four injection) tied back directly to the FPSO through ten flowlines, ten risers and two dynamic umbilicals to provide power, control and subsea chemicals.

Personnel safety, process safety, and environmental performance were prioritized during start-up. Liza Unity achieved background flare within 60 days of start-up with operations continuing to bring new wells online and achieve the initial investment basis oil production capacity of 232 kbd in six months.

This paper will present:

The strategy and integrated approach to achieve first oil, ramp up to the initial investment basis oil production capacity, and production optimization, while maintaining focus on personnel safety, process safety and the environment Well start-up strategy, reservoir data gathering, and reservoir management of a complex reservoir with wide range of fluid properties Start-up challenges and mitigations First Water-Alternating-Gas (WAG) conversion in Guyana Reliability performance

The overall journey from first oil to achieving the initial investment basis oil production capacity was carried out by the Liza Unity team within its first year of operations. This is a result of an integrated approach demonstrated by all the technical and operations disciplines. This paper will elaborate on the challenges tackled by Liza Unity while generating value for all the stakeholders and the people of Guyana.
Digital Twin for Development & Subsurface Integration - A Window into the Future
Authors: Gan T. , Sumadh E. , Sagram B.
Published: October 2023

The Digital Twin (DT) provides a virtual and digital representation of existing assets, spanning everything from onshore facilities to offshore platforms, pipelines and subsurface data, all in one location. It has been used for the flagship Manatee project to develop 3 stacked reservoirs, which will be one of the largest projects in Shell Trinidad and Tobago (STT). Gas from these wells is expected to be processed via a new platform and transported via a long offshore pipeline pipeline to the Beachfield onshore facility. The DT was used to identify design modifications required at this onshore site and visualize the proposed offshore assets. It integrates existing facilities and new design data, including site survey, subsurface and wells data to optimize the well planning.

With access to an integrated visualization platform for both surface and subsurface 3D and 4D data and engineering design documentation, virtual site visits were conducted to assess the existing facility. Integrating the 3D model with the pipelines, bathymetry data of the proposed pipeline routes and subsurface data, the team was able to design and engineer future upgrades required for the upcoming development. Furthermore, DT was used to visualize the proposed well paths, platform design, rig access and subsurface reservoir data which supported platform location, layout, and orientation decisions.

The full project scope, in the form of a complete 3D model was created for both onshore and offshore assets. DT allowed the teams to have a better understanding of the site layout and area constraints that would have been impossible to envisage using 2D drawings alone. The proposed models assisted with identifying possible design issues, thus reducing the likelihood of errors and lowering costs associated with rework and corrections. The teams used high-resolution photogrammetry to support the environmental team in determining the best landing site for the pipeline and fiber optic cable. This was done by navigating through bathymetry and geohazards to land the new pipeline route from the platform to Beachfield. Overall, access to a digital representation of the facilities, led to a significant manhour saving for the teams, enabling integrated, efficient working and improved decision quality.

Overall, the use of the DT has been estimated to deliver direct cost savings of several millions per year and generate double digits millions of indirect value from safety design and rework during project decision gates handover and project schedule integration. Furthermore, given the limitations due to the pandemic, CO2 emissions and the carbon footprint were lowered as there was a reduced number of helicopter flights offshore and drives towards the onshore facilities.
A Fast Adaptive Integral Method for Estimating Stress Distribution and Failure in Large Natural Fracture Networks
Authors: Cao Meng , Sharma Mukul M.
Published: October 2023

The displacement discontinuity method (DDM) is a powerful method for hydraulic fracturing simulations. However, the computational time for this method increases exponentially as the number of fracture elements increases. This occurs primarily because the method involves the multiplication of a large dense matrix with a vector. In this study, a fast adaptive integral method (AIM) is used to reduce the computational time significantly when solving for the displacement field in a large complex fracture network.

The key to the fast Fourier transform (FFT)-based adaptive integral method is the fast matrix-vector multiplication algorithm. The large dense matrix is decomposed into far-field and near-field components. The far-field component is computed by using the uniformly spaced Cartesian grids, and this component provides the foundation to perform discrete fast Fourier transform. The sparse near-field component is calculated by using the grids for fracture elements. Based on the split of dense matrix into far-field and near-field components, FFT is applied to accelerate the multiplication of matrix and vector since no dense matrices are used.

A large fracture network is used to compare AIM with the standard DDM method. It is shown that the fast matrix-vector multiplication algorithm provides a very good approximation of the dense matrix. The accuracy of the fracture displacements is computed for different fracture orientation patterns. It is shown that the displacement calculated by AIM matches the displacement calculated by DDM very well. A comparison of the computational time for both the extended FFT-based AIM and DDM indicates that for small-scale problems, DDM performs as well or even better than AIM because extra computational time is needed for the correction between near neighbors and propagation on a regular grid. However, for large fracture networks with a large number of elements, the computational time needed by AIM is orders of magnitude less than that needed by DDM. The advantages of fast Fourier transform are then fully utilized to compute matrix and vector multiplication.

The new algorithm (extending FFT-based AIM) provides a novel method for solving stresses and displacements in large-scale fracture networks. It is capable of drastically reducing the computational time for such problems with very little loss in accuracy.
Physics-Based Machine Learning Models for Real-Time Prediction of Rheological and Filtration Properties for KCl Polymer Mud
Authors: Abdulwarith Abdulrahman , Dindoruk Birol , Livescu Silviu
Published: October 2023

The rheology of drilling fluid is a crucial component during drilling operations to achieve optimum performance and avoid non-productive time resulting from drilling problems. In field operations, measuring the rheological and filtration properties of drilling fluids necessitates a significant amount of preparation time and experimental work. Often, such data analysis is not conducted on a footage basis. However, some surface parameters, such as mud weight using the mud balance, marsh funnel viscosity using the Marsh funnel, and mud flow line temperature, can be measured in real-time. This study introduces physics-based machine learning models for real-time prediction of both rheological and filtration properties. The machine learning algorithms used include support vector machines (SVM), extreme gradient boosting (XGB), random forests (RF), and multilayer perceptron networks (MLP). These models predict the rheological and filtration properties based on collected field experimental data. The model inputs are mud weight, marsh funnel viscosity, and flow line temperature, while the targets are apparent viscosity (AV), yield point (YP), plastic viscosity (PV), shear stress based on Fann readings at 600, 300, 200, 100, 6, and 3 shear rates in terms of revolutions per minute (RPM), and filtration loss volume. The developed machine learning models underwent hyperparameter tuning based on cross-validation to select the optimum model for each algorithm using the coefficient of determination (R2) and absolute average relative error (AAPRE). Furthermore, all machine learning model predictions were tested and validated using various datasets. The SVM models' performance ranged from 0.85 to 0.97 in terms of R2, with most AAPRE values less than 2%, reaching a maximum of 6%. The developed RF models ranged from 0.94 to 0.97 in terms of R^2, with AAPRE values between 2 and 3%. XGB models ranged between 0.95 and 0.98 in terms of R^2, with AAPRE values from 1 to 2%. The MLP models ranged from 0.991 to 0.99 in terms of R^2, with AAPRE values less than 6%. The developed machine learning models exhibited high accuracy in predicting the mud's rheological properties in terms of PV, YP, and n, with AAPRE values less than 1.94%, 1.77%, and 4%, respectively.
Subsurface Injection Monitoring in Complex Geologic Media Using Pathline, Source Cloud and Time Cloud
Authors: Li Ao , Chen Hongquan , Jalali Ridwan , Al-Darrab Abdulaziz
Published: October 2023

Monitoring of subsurface fluid motion is critical for optimizing hydrocarbon production and CO2 sequestration. Streamlines are frequently employed to visualize fluid flow; however, they provide only an instantaneous snapshot of the velocity field and do not offer an exact representation of fluid movement under varying field conditions. In contrast, pathlines are constructed by tracking individual particles within the fluid, enabling us to trace the movement of these particles as they traverse through changing velocity fields. This paper presents the development and application of pathlines for flow visualization in complex geologic media. The flow visualization is further aided by source cloud (streak lines) and time cloud (isochrones representing moving fluid fronts). We demonstrate the power and utility of the developed tool in fractured media using Embedded Discrete Fracture Model (EDFM).

Pathlines track the history of flowing particles in the reservoir. Pathlines can be spliced from streamline segments over time, tracing the trajectory of a particle under changing velocity fields. For each interval, a pathline’s end is extended with a streamline segement whose elapsed time of flight (TOF) equals the time interval. Based on the pathlines, streaklines and timelines can also be visualized. Streakline is formed by all fluid particles emitted at the same location. Timeline is the contour formed by all fluid particles emitted at the same instant and represents the fluid front movement. In 3D, these two concepts are more generally visualized in groups of points rather than lines, so we refer to them as source cloud and time cloud.

The proposed injection monitoring methods - Pathline, Source Cloud and Time Cloud - are tested using a 3D field-scale model with complex geologic features to demonstrate its power and utility. The pathlines were compared with streamlines, time of flight and the water saturation distribution. Three scenarios are tested: a constant well schedule, a changing well schedule with shut-ins, and a changing well schedule with fully injection cease. Results indicate that the pathline provides more accurate swept volume, consistent with saturation distribution. The robustness of our algorithm and implementation is demonstrated with a complex Embedded Discrete Fracature Model (EDFM) with non-neighbor connections to visualize flow patterns in discrete facture network. Pathlines display the fluid flow across fractures and are subsequently used to examine the sweep efficiency and the well connectivity.
A Dynamic Assessment for Maximization of Synergy Through Integration of Two Operations. Case Study
Authors: Cagliero G. J. , Cavallin S. , Ventocilla S.
Published: October 2023

Resume

When two businesses decide to integrate, they can generate synergy. An effect that causes the value of the whole to be greater than the sum of the parts.

The additional value generated can be identified through an economic model that, based on the behavior of key variables (input), estimates not only the benefit for each party, but also the synergy.

With such a model, through scenario simulation, sensitivity and data analysis, an equilibrium point can be found where the value of synergy is equitably distributed between the parties.

This economic model can be simplified through an equation based on a multivariate regression with the following objectives:

Simplify the behavior of variables and understanding of cash flows, so that the parties can negotiate commercial, technical, legal and contractual conditions. Distribute equally the value generated even when conditions change. Estimate a margin of error acceptable to all parties.
A Novel Approach to Estimating Pressure Depletion from 4D Seismic Softening Signals Along Oil-Water Contact. A Practical GoM Application
Authors: Bao Chen , Colmenares Luis
Published: October 2023

A foundational principle in the safe development of mature fields is to understand pressure depletion across the different reservoirs. A proper estimate of pore pressure guides not only in-place volumes and expected recoverable, but also heavily impacts the design and safe drilling of wells. Methods to determine reservoir pressure vary, from offset-well extrapolation to numerical modeling, depending on the particulars of the field. In this work, we present a novel approach to estimate field wide pressure depletion from 4D seismic softening along OWC signals.
Controlled CO2 Injection into Storage Reservoirs to Minimize Geomechanical Risks Under Geologic Uncertainty
Authors: Zheng F. , Jha B. , Jafarpour B.
Published: October 2023

Carbon Capture and Storage (CCS) has gained recognition as a mitigation strategy for reducing the accumulation of atmospheric CO2. However, the injection of CO2 into storage reservoirs can lead to increased pore pressure, which in turn induces stress changes in and around the injection site. These stress changes may give rise to several geomechanical hazards, including caprock failure, ground surface uplifting, and induced seismic activity. To address this concern, we have developed a novel optimization approach aimed at maintaining the caprock integrity during the storage of CO2 in geologic formations under geological uncertainty. The developed workflow integrates advanced numerical optimization algorithms with coupled multiphase flow-geomechanics-fracturing models for simulating the response of the storage reservoir to CO2 injection. Using the geomechanical response of the simulation, we define and quantify the potential caprock failure and CO2 leakage risks. An optimization formulation is used to minimize the risk of caprock fracturing and CO2 leakage by finding the optimal distribution of dynamically changing CO2 injection rates across several wells throughout the injection period. The results are extended to incorporate the uncertainty in the simulation model through ensemble-based optimization. The proposed optimization approach identifies the well injection schedule (flow rate vs. time profile) to minimize the risk of caprock fracturing by distributing the pressure increase in the heterogeneous reservoir. The optimization process is designed to continually enhance the injection strategy, aiming to minimize the potential for caprock fracturing by maximizing the stress differences between the minimum effective stress and the fracture opening stress. The paper highlights the importance of employing coupled flow and geomechanics, along with fracture mechanics, in accurately modeling and predicting the potential CO2 leakage. This approach enables the development of injection strategies that prioritize caprock integrity, effectively addressing the challenges associated with optimizing CO2 storage while minimizing the risk of caprock failure.
Non-Intuitive Choke Control During Clean-Up Operations Allows Significant Reduction of Emissions
Authors: Theuveny B. , Rashid K. , Bailey W. , Gemmell D. , Comley R.
Published: October 2023

Every well needs to be cleaned-up, at least once – after the end of the well construction phase but could be after stimulation operations or workovers over their full life.

The clean-up / flowback operations are sometimes executed with a full or partial disposal of the fluids as either no production system is available (the case of most exploration and appraisal wells) or when the production system is intolerant to the fluids produced (low pH. High solid content, excess water, or for rheology incompatibilities). The disposed fluids are sent to a flare and their combustion induce a significant amount of emissions. These operations are typically executed according to the prior experience of similar wells.

The paper presents a novel approach to significantly reduce emissions by optimizing the clean-up operation by varying the choke settings in rapid interval at surface. Field case confirm the ability to significantly reduce the duration and the quantity of fluids flared in these operations and accelerating the time to shift the flow to the production line – if available.

The challenge is that every well configuration leads to a different choke schedule that minimizes emissions. This is due to the complex combination of near wellbore properties of the formation and the invaded fluids, the complexity of the well trajectory and the variability of fluids used to kick-start the well. It is intuitive that the acceleration of the choke change would lead to a reduction of the emissions. This leads to a reduction of 10 to 30% of the CO2 balance. To achieve superior savings, it is necessary to consider a reduction of the maximum rate – which can lead to 50% range of reduction in some wells. Further improvements are achieved with more complex choke sequences that the paper describes.

This novel method consists in the detailed prediction of the dynamics of the flow during the clean-up operation is a key element to optimize the choke sequence. A rapid model allows to evaluate several scenarios and select the optimum settings that will achieve a significant reduction in emission while keeping the near well bore in a safe operating zone (geomechanical phenomena), protect the integrity of stimulated zones, and guarantee the safety of the completion (collapse). Finally, several contingency cases are considered to ensure that a robust operation can safely be delivered.
A Comprehensive Study of a Novel Submersible Pump
Authors: Banjar Hattan , Xiao Jinjiang , Ejim Chidirim , Badr Hassan , Al-Sarkhi AbdelSalam
Published: October 2023

Electric submersible pumps (ESPs) are over a century-old technology. As reservoirs mature, water cut increases, motor electric load increases which in turn, increases the required equipment size, mainly the pump and motor lengths. In addition, in alternative ESP deployment methods, length of the ESP is a critical factor during installation and retrieval due to crane limitations especially for offshore. To mitigate the downhole assembly length, a novel motor and pump system is designed. The primary advantage of this design is manifested by the elimination of the protector section that represents a problematic component in a typical electric submersible pump (ESP). This study focuses on the feasibility assessment of the concept at given conditions, where the motor and the pump are integrated concentrically in one unit inside a cylindrical housing in an arrangement suitable for downhole.

A comprehensive system design involving electrical, mechanical and hydraulic analysis was carried out to develop a Permanent Magnet Pump (PMP) with performance characteristics matching a typical conventional ESP. A number of factors affecting the new ESP system were considered. They include maximum radial dimension constraint, high flow rate and total dynamic head requirements, motor cooling, the need to maintain reasonably high efficiency over a wide range of flow rates, sand and gas handling, and finally the ease of manufacturing and system assembly.

An architecture based on a labyrinth screw pump was found to be the most appropriate one for use in the 562 series motorized pump design. Detailed calculations on pump and motor were conducted to determine the system dimensions and performances. For typical field applications with rates ranging from 4000 to 5000 BPD and total dynamic heads ranging from 3000 to 4000 ft, a system made of forty-five stages with an approximate length of 45 ft was found to be sufficient. The PMP overall efficiency ranged from 52% to 58% while the operating speed ranged from 3700 to 4500 RPM. Motor cooling was achieved by circulating part of the pumped fluid back to the pump suction side through the air gap. The fluid temperature increase ranged from 20°F to 30°F, when brine is the pumped fluid.

This comprehensive work assessed the feasibility of developing a novel, motorized pump for downhole artificial lift applications. It is clearly shown that this new ESP architecture is feasible and practical. With this new design, a next generation of ESPs can be built without the conventional motor seal/protector sections, eliminating one of frequent failure components. In addition, the ESP overall length can be shortened, paving the way to develop a more compact, rigless ESP deployment and retrieval technology for further reduction in operational cost and production deferral.
Novel Single Phase Retarded Acid System for Effective Stimulation of Limestone Reservoirs
Authors: Qamruzzaman Mohammed , Nain Pooja , Mhaske Ganesh , Ravishankar Burla , Nischal Rajiv
Published: October 2023

HCl based stimulation fluids occupy the dominant space in matrix acidizing of limestone reservoirs. To initiate wormhole propagation at high temperature/low injection rates and provide deeper penetration, the reactivity of HCl is generally retarded by emulsifying it with an external hydrocarbon phase like diesel. Although it solves the issue of high HCl reactivity, its performance is found to compromised for reservoirs with bottom hole temperature more than 135°C where the emulsion suffers from stability issues. The high viscosity of emulsified acid restricts the pumping rate especially for the cases where the well is having ESP completion or the job is being done through CTU. Also, around 30% of emulsion comprises of diesel which poses health hazard, reduces rock dissolution capacity and incurs extra cost. To counter these challenges, this paper presents a new single phase/aqueous retarded acid formulation that consists of special water-soluble acid retarders which slow down the rate of consumption of HCl. The retardation effect observed is even more than what is observed with emulsified acids while maintaining a high dissolution capacity and low fluid viscosity. A comparative analysis of acid retarders on HCl reactivity has been shown through bench top reaction studies. Suitable corrosion inhibitors compatible with the acid retarders have been identified and the final formulation has been tested through core flooding experiments coupled with Micro CT scan for its effectiveness. Results from lab study indicate that the single-phase retarded acid system requires lesser pore volumes to breakthrough than the conventional acids over wide range of injection rates. Also, dominant wormhole regime has been observed with its use under the conditions where facial dissolution and conical wormholes were found with plain acid and emulsified acid respectively. The developed formulation will be very helpful in increasing the effectiveness of stimulation in limestone reservoirs with special applications in high temperature, horizontal and injectivity compromised wells. Replacing the emulsified acid application with the developed formulation will help in reducing carbon footprint and make job execution simpler, safer and easier.
Evaluation of Metabolic Profiles of Berari Goats in the Transition Period
Authors: Hajare Nikhil Dansing , Kuralkar Prajakta Shailendra , Hajare Sunil W. , Deshmukh Shyam G. , Deshpande Kuldeep Y. , Kuralkar Shailendra Vasantrao , Murkute Pranjali
Published: October 2023

The study aimed to investigate the influence of physiological status on the blood metabolic profile of Berari goats in Vidarbha climatic conditions. Blood samples were collected from 12 healthy pregnant goats 21 days before kidding, on the day of kidding, and 21 days after kidding. The samples were analyzed for non-esterified fatty acid (NEFA), total cholesterol (TC), triglyceride (TG), glucose (Glu), total protein (TP), albumin (Alb), globulin (Glb), alanine transaminase (ALT), aspartate transaminase (AST), calcium (Ca) and phosphorous (P). The transition period had significant effect on TG (26.71 ± 2.52a, 17.05 ± 1.90b, 20.83 ± 1.66abmg/dl), TP (6.13 ± 0.23b, 6.57 ± 0.35b, 8.22 ± 0.29ag/dl), globulin (1.48 ± 0.30b, 1.67 ± 0.34b, 3.69 ± 0.32ag/dl), glucose (66.78 ± 3.30b, 183.47 ± 32.65a, 81.41 ± 6.60bmg/dl) and phosphorus (8.96 ± 0.67a, 5.38 ± 0.79b, 6.59 ± 0.29bmg/dl). The study indicates that the Berari goats were not under metabolic stress and were well-adapted to the tropical and arid climatic conditions of the region. The higher glucose level observed during kidding suggests that the animals were in positive energy status and well-managed during the transition period.
Femoral nerve palsy as a complication due to COVID-19 coagulopathy and iliopsoas muscle hematoma after total hip replacement – case report
Authors: Tutak Sławomir , Bartosz Paweł , Burda Bartosz , Sztwiertnia Paweł , Białecki Jerzy
Published: October 2023

Background: COVID-19 (Coronavirus disease 2019) pandemic is the main medical problem around the world from the end of 2019. We found until now many symptoms of this disease, but one of the most problematic was thrombosis. Wide recommendation on COVID-19 treatment was pharmacological thromboprophylaxis. In some papers we found that clinicians face the problem of bleeding in those patients. Is still unknown that coronavirus could led to the coagulopathy.
Case presentation: We described case report of patient who with COVID-19 disease present femoral nerve palsy caused by the iliopsoas hematoma. There were no deviations in coaguology parameters, patient got standard thromboprophylaxis, besides above probably COVID-19 was risk factor of hematoma formation. Non-operative treatment was applied, thrombophylaxis was discontinued. In the follow up in the radiological exam we saw reduction of the haematoma and patient report decrease of symptoms.
Conclusions: We should assess individually patient with COVID-19 according to thrombosis risk factors. Probably we should be more careful in ordering thrombophylaxis medications in COVID-19 patients.
The future of MEG: Improved task-related responses using optically-pumped magnetometers compared to a conventional system
Authors: Safar Kristina , Vandewouw Marlee , Sato Julie , Devasagayam Jasen , Hill Ryan , Rea Molly , Brookes Matthew , Taylor Margot
Published: October 2023

Optically-pumped magnetometers (OPMs) offer a new wearable means to measure magnetoencephalography (MEG) signals, with many advantages compared to conventional systems. However, OPMs are an emerging technology, thus characterizing and replicating MEG recordings is essential. Using OPM and cryogenic MEG, this study investigated evoked responses, oscillatory power, and functional connectivity during emotion processing in 21 adults, to establish replicability across the two technologies. Five participants with dental fixtures were included to assess the validity of OPM recordings in those with irremovable metal. Replicable task-related evoked responses were observed in both modalities, with the OPMs demonstrating higher peak amplitude and improved signal-to-noise. Similar patterns of oscillatory power to faces were observed in both systems. Increased connectivity was found in cryogenic versus OPM MEG in an occipital and parietal anchored network. Notably, high quality OPM data were retained in participants with metallic fixtures, from whom no useable data was collected using cryogenic MEG.
A miniature of soluble methane monooxygenase enables
Escherichia coli to rapidly produce methanol with high yield
Authors: Lee Jeewon , Yu Yeonhwa , Shi Yongfan , Kwon Young-Wan , Choi Yoobin , Kim Yusik , Na Jeong-Geol , Huh June
Published: October 2023

Soluble methane monooxygenase (sMMO) oxidizes a wide range of carbon feedstocks (C1 to C8) directly using intracellular NADH and is a useful means in developing green routes for industrial manufacturing of chemicals; however, the high-throughput biosynthesis of active recombinant sMMO and the ensuing catalytic oxidation have so far been unsuccessful due to the structural and functional complexity of sMMO, comprised of functionally complementary, three enzyme components, which remains a major challenge for its industrial applications. Here we developed a catalytically active miniature of sMMO (mini-sMMO) through an optimal reassembly of minimal and modified components of sMMO on catalytically inert and stable apoferritin scaffold, with demonstrating the molecular characteristics in detail through in silico and experimental analyses and verifications. Notably, the in-situ methanol production in the high-cell-density culture of mini-sMMO-expressing recombinant Escherichia coli resulted in a remarkably higher productivity compared to the traditional methanotrophic production.