bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Spiral Shaped Soft Holding Actuator Using Extension Type Flexible Pneumatic Actuators
Authors: Shimooka So , Akagi Tetsuya , Dohta Shujiro , Shinohara Takashi , Kobayashi Takumi ,   Graduate School of Natural Science and Technology, Okayama University 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan,   Department of Intelligent Mechanical Engineering, Okayama University of Science 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan,   Design and Manufacturing Center, Organization for Research Development and Outreach, Okayama University of Science 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
Published: April 2022

Recently, several pneumatic soft actuators have been applied to wearable and welfare devices to provide nursing care and physical support for the elderly and disabled. In this study, as a wearable soft actuator for holding body, a spiral shaped soft holding actuator that can wrap a user according to their body shape was proposed and tested. The construction and operating principle of the tested soft actuator with circumferential restraint mechanism using three extension type flexible pneumatic actuators (EFPAs) has been discussed. As a result, it was found that the tested actuator could hold elbows and knees when the joint is in motion. An analytical model of the spiral actuator was also proposed to achieve an optimal design. It can be confirmed that the proposed analytical model can predict the shape of the actuator when various EFPAs are pressurized.
Development of Flexible Deformation Mobile Robot Composed of Multiple Units and Pneumatic Self-Excited Valve
Authors: Hada Takuya , Iguchi Kenta , Aoki Takeshi ,   Chiba Institute of Technology  2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan,   MagnaRecta, Inc.  4-6-10 Nihombashi-honcho, Chuo-ku, Tokyo 103-0023, Japan
Published: April 2022

In this study, we developed new bending modules and pneumatic self-excited valves. In a previous study, we developed a planar flexible-deformation mobile robot that combines multiple bending modules. The robot moves by a traveling wave, which is periodically generated by pressurizing air to the bending modules. Further, it can move in every direction by simultaneously combining the two directional traveling waves. However, problems such as air leakage from the bending module that constitutes the moving object and the influence of the moving operation owing to the tubes comprising the flow path were identified. To address these problems, new bending modules have been developed. To address air leak issues, we verified the materials used in the bending modules and developed an injection mechanism. To reduce the number of externally connected tubes, we developed new bending modules that could include multiple internal flow paths. In addition, because the mobile robot moves owing to the generation of traveling waves, it is a low-grade operation. However, this requires multiple solenoid valves and electronic circuits. This is useful if traveling waves can be generated by simply supplying air using a pneumatic self-excited valve. In this study, we developed bending modules with multiple internal channels and a pneumatic self-excited valve that utilizes the snap buckling of leaf springs used in the mobile robot.
Case Study regarding the Stress Distribution and Microseismic Laws of Coal and Rock Underlying the Residual Coal Pillar
Authors: Liu Yang , Lu Cai-Ping , Zhang Xiu-Feng , Guo Ying , Song Jie-Fang , Song Chun-Hui
Published: April 2022

The stress distribution characteristics, stress gradient evolution, and focal mechanism of microseism (MS) events during mining of working face 103_ (lower) 07 under an overlying residual coal pillar were investigated. Numerical simulations and MS observations were utilized. The coupling relationship between the stress gradient and MS activity was also analysed, which indicated the correlation between the fracture of coal/rock and stress gradient. In addition, the secondary disturbance of the coal mining underlying a fractured hard-thick roof is discussed. The following four points were addressed: (1) the high stress initially concentrated under the edge of the overlying residual coal pillar, and its contribution to both the local coal and rock fracture and the significant change in the stress gradient; (2) the deformation and fracture first occurred in coal and rock underlying the edge of the residual pillar. The stress concentration gradually transferred to the interior of the pillars and was accompanied by the failure of coal and rock; (3) a high correlation between the deformation and fracture of coal/rock and the stress gradient was observed. The fractures under the pillars principally appeared in the high-stress gradient area; (4) the disturbance caused by mining of the underlying working face may cause instability of the high-level fractured roof, accompanied by high-energy MS.
POPULATION OF Ascaridia galli ACCORDING TO ITS PREDILECTION AFTER BEING TREATED WITH ARECA NUT INFUSION AND ITS ECONOMIC ANALYSIS
Authors: Sudarmanto Bambang , Akbarrizki Muzizat , Mubarokah Wida Wahidah
Published: April 2022

This study aims to determine the effectiveness of Areca catechu Crude Aqueous Extract (ACCAE) as an anthelmintic, the number ofAscaridia galli worms in the duodenum, jejunum, and ileum after treatment, and an economic analysis. In this study, 50 female chickens wereused. The chickens were divided into 5 groups: Treatment 1, negative control (P1), which was given aquadestylates; treatment 2 (P2), which wasgiven infusion of ACCAE at a dose of 26 mg/mL; treatment 3 (P3), which was given infusion of ACCAE at a dose of 53 mg/mL; treatment 4(P4), which was given ACCAE with a dose of 79 mg/mL; and treatment 5 (P5) (positive control with pyrantel pamoat). Each group consisted of10 chickens. An examination was carried out that included weighing the population of adult worms according to their predilection 14 days aftertreatment. Weighing was carried out at the beginning before treatment, on the 7th day after treatment and on the 14th day after treatment. Thechickens were then euthenized, the intestinal worms were counted, and the economic analysis was calculated. Based on the results of the study, itcan be concluded that the best dose for removing A. galli worms is 79 mg/mL, and the location of the predilection of the intestine where the mostworms are found is the jejunum and the least is in the ileum. Economically, the highest income was obtained from treatment 4, namely the groupwith infusion of areca nut at a dose of 79 mg/mL.
Renewables, Energy Transition, and the Future of Conventional and Unconventional Oil & Gas in California
Authors: Aydin Hakki , Temizel Cenk
Published: April 2022

Historically, renewable energy technologies have been seen as a source of competition by the oil and gas industry. However, the oil and gas industry is now one of the primary sources of investments in renewable energy technologies. The oil and gas industry in California, in particular, has been making significant investments in renewables and leveraging the latest renewable energy technologies to reduce the carbon footprint of oilfield applications. This study analyzes the latest advances in renewable energy solutions, their impact on energy transition efforts in the state, and the potential of further developing conventional and unconventional oil and gas resources in California.

This paper has focused on conducting a thorough review of literature related to the latest advances in renewable energy technologies and energy transition efforts in California and the applications of these technologies in reducing the carbon footprint of oilfield activities, along with examples of renewables as a complementary resource to oil and gas. Furthermore, the availability of conventional and unconventional oil and gas resources in the state has been summarized. The potential of developing these resources in the future is analyzed in detail. The literature includes a comprehensive set of references ranging from peer-reviewed journal publications and proceedings to data from market studies and other non-technical publications and market predictions by renowned experts.

The position of renewable energy resources either as a competing or complementary source to oil and natural gas in California and the impact of these resources in energy transition efforts in the state are discussed. Examples of the use of renewable energy technologies to improve various processes within oil and gas production operations are provided, and the prospect of further developing conventional and unconventional oil and gas resources in the state has been investigated to conclude the impact of both these energy sources to the regional energy supply and demand dynamics. In addition, the benefits, drawbacks and challenges in scaling up the use of these energy sources are discussed in detail.

This study provides a comprehensive overview of the current status of renewable energy resources, energy transition efforts, and the future of conventional and unconventional oil and gas resources in California. It serves as a single source of reference to the oil and gas industry in laying out relevant data and information related to renewable energy resources from the point of view of oil and gas market dynamics and closes the gap in highlighting the latest advances and the future of the energy industry in California.
Rod Pump Status and Efficiency Monitoring with High Frequency, High Resolution Surface Pressure Data
Authors: Gordon Ryan David , Ito Tokunosuke
Published: April 2022

Rod pump monitoring and optimization has traditionally relied on polished rod load and position data. We set out to prove that tubing pressure monitoring is an effective alternative optimization tool to traditional rod pump diagnostic tools.

Pressure monitoring devices, based on an internet of things (IoT) architecture were installed on the flow tee of pumpjacks in a variety of fields. Each device continuously captured, stored, and delivered high-quality, time-synchronized, per-second pressure measurements to a cloud-based data service. Over time, with firmware upgrades to the device, higher frequency sampling was implemented. At a sample rate of 13.3 Hz, a clear, stroke-by-stroke view of changes associated with the movement of the bottomhole pump emerges. A method for estimating efficiency and diagnosing bottomhole pump conditions was developed utilizing only the velocity profile of the polished rod, bottom hole pump plunger diameter and polished rod diameter.

Through observation of pressure data and correlating it to available field data, an efficiency calculation method was developed. The velocity profile of the pump jack, the polished rod diameter, and the bottom hole pump diameter are used to generate an expected pressure profile for a 100% efficient pump. Deviations from the expected pressure profile are used to estimate pump efficiency and diagnose problematic pump conditions. The volumetric efficiency of eight wells was estimated and compared to the volumetric efficiency calculated from test data. The sample size was not adequate to validate the method, but the results gave initial indications that showed the method has promise.

Current rod pump monitoring solutions can be cost prohibitive when evaluated for aging wells, which make up most of the North American production. Using accurate, high frequency pressure data to evaluate rod pumping performance looks to be a promising low-cost alternative to conventional rod pump monitoring methods.
Improved Reverse Osmosis Membranes for Treating Produced Water
Authors: Franks Rich , Huang Xiaofei , Bartels Craig
Published: April 2022

For many years, reverse osmosis (RO) elements have been used in the treatment of produced water, including at several sites in California. The RO reduces salts and organics in the produced water to a level that allows for disposal or reuse. The RO elements used to treat produced water are similar in chemistry and construction to the conventional seawater RO membrane. But compared to seawater, the characteristics of produce water are unique and varied. The conventional seawater membrane comes with pressure and temperature limitations that restrict its ability to treat a wide range of produced waters. Specifically, conventional membranes have a temperature limit and a pressure limit. Only a portion of the produce waters needing treatment fall within the membrane's temperature and pressure limitations. Many produced waters, including produce waters associated with SAGD, require membranes that can accommodate higher temperatures up to 60 C. Other produced waters may allow for treatment at ambient temperatures but their higher salinities above 60,000 mg/l TDS require RO membrane to overcome high osmotic pressures and operate at feed pressures up to 1800 psi.

In recent years, membrane manufacturers have enhanced their exiting RO elements to address the challenges associated with the treatment of unique industrial streams such as produced water. Specifically, new, more robust element construction allow designers to push beyond the normal limits of temperature and pressure. One such element allows for operation at temperatures up to 90 C while a second, ultra high-pressure RO (UHPRO), can concentrate the total dissolved salts (TDS) up to 120,000 ppm (12%) while operating at pressures up to 1,800 psi (124 bar).

These unique elements can be used to increase the overall efficiency of the treatment facility by reducing the cost of brine disposal and maximizing water recovery. This paper will show how these new elements perform when operated beyond conventional pressure and temperature limits - including how individual ion passage and water permeability are affected at extreme conditions. This paper will share element performance data from laboratory and pilot studies. The data will be used as a basis for new designs at the extreme conditions associated with produced water treatment.
Time Series Analysis as an Alternative for Decline Curve Analysis in Unconventional Plays
Authors: Malaieri Mohammadreza , Matoorian Raya , Shor Roman J.
Published: April 2022

Quick and reliable forecasting of production data is still challenging in unconventional plays, even with the variety of modifications proposed to Arps decline curve analysis (DCA). Machine learning revealed promising results when enough samples were accessible to train and validate the predictive model. However, this black-box model is inaccurate for unseen samples, challenging to generalize, and requires too much data. We attempted to present an alternative procedure to solve this problem —a fast and reliable method outperforming current approaches.

In this study, we implemented univariate and multivariate times series analysis (TSA) to forecast production rate in the different scales (wellbore, field, and pad scales) where DCA failed to provide an appropriate fit beforehand. TSA is straightforward and enables recognition of the pattern in observation samples. Cyclic fluctuation due to seasonal changes in price and operational hours can be detected and indirectly considered in time series models like ETS (Exponential Smoothing) and ARIMA (Auto-Regressive Integration Moving Average). However, for the direct considerations of these critical parameters, Vector Auto-Regressive (VAR) models have the flexibility and ability to be configured with multiple variables and can capture more complexities.

This simple and quick procedure applies on any scale from the wellbore to the field scales. To evaluate the performance, the TSA method has been applied and tested on data from the Duvernay shale in Western Canada. On the wellbore scale, modified DCA models forecast production rate with over/underestimation, even where enough observations are available, and if the well has shown a declining trend in the production. In the same wells, TSA provides a better fit and outperforms the DCA. In the field and pad scales, DCA could not draw a fitting model as production had a growing trend due to ongoing field developments. In contrast, TSA could realize the trend in the production data and successfully create the forecasting model. Price and production hours were added to the time series model as influential features on production. The model could forecast all the parameters simultaneously. In sum, TSA is a reliable and flexible alternative for DCA and can be implemented on production data in any scale.
Detection of 2.187 Gallon Pipeline Leakage by Optical Sensor Based on Coherent Interaction of Pulse and Depleted Pump Technology
Authors: Zou Lufan , Sezerman Omur
Published: April 2022

Pipelines provide one of the safest and most reliable means for transportation of oil and gas. Due to the severity of the economic and environmental impacts associated with leakages, the industry is constantly seeking more efficient and reliable monitoring systems. Extending the sensing range on long-distance pipelines is a challenge. Increasing the optical power to compensate for higher attenuation or lower SNR due to the fiber length increases the risk of fire when a rupture occurs. A coherent probe-pump-based Brillouin sensor with less than 1mW (Laser Class 1M) of cw pump power has been developed for use with sensing fibers up to 200 km. It works by controlling the depletion of the pump beam resulting from the strong coherent interaction of the probe and the depleted pump (CIPDP). The initial results from detection of pipeline leakage using a DSTS based on CIPDP technology are presented. The overall goal of the experimental procedure is to assess the leakage detection capabilities of the optical sensing technologies. A blind test methodology was followed in which the number, position, and time of the leaks were not known beforehand to the sensor manufacturers. Approximately one-third of the pipe diameter was embedded in soil, so leaks were limited to the lower portion of the pipe. The remainder of the pit was filled with water. Within the pipeline, a system of tubing and valves was used to route the test fluid to the appropriate locations to simulate leaks. A leakage volume of 2.187 gal was detected in one minute by a DSTS based on CIPDP technology. This simulated leak happened through a 1/8″ orifice with an injection pressure of 105 psi and a difference of 39°F (21.6°C) between the line temperature and the soil temperature. When the injection pressure dropped to 22 psi and the difference between the line temperature and the soil temperature dropped to 20°F (11.1°C), leakage volumes as small as 6.72 gal were detected in 5 minutes. All leaks with different volumes controlled by injection pressure, orifice, line temperature, and duration were detected successfully.
First Successful LWD NMR T1 and T2 Measurements in Unconventional Source Rock with Harsh Drilling Environment: A Case Study from Kuwait
Authors: Abdulkarim Anar , Aki Ahmet , Balliet Ron , Al-Azmi Mejbel Saad , Al-Otaibi Fahad Barrak , Joshi Girija Kumar
Published: April 2022

The thickness and thermal maturity of the Najmah formation presents a favorable prospect for commercial exploitation of unconventional shale gas. Estimating reservoir storage volume is one of many formation-evaluation objectives when assessing an unconventional reservoir.

The presence of kerogen has significant effects on several downhole logging sensor measurements. An operator used nuclear magnetic resonance (NMR) measurements to evaluate total fluid-filled porosity for a reliable estimate of the reservoir storage volume in source rock. While wireline NMR has historically provided a large segment of unconventional reservoir logging, logging-while-drilling (LWD) NMR provides an alternative method for assessing the total fluid-filled porosity within unconventional reservoirs.

This paper provides a case study in the Najmah Shale Formation, where an operator used an LWD penta-combo system (gamma ray, electromagnetic wave resistivity, azimuthal bulk density, thermal neutron porosity, high-frequency multipole azimuthal sonic, ultrasonic caliper, and NMR sensors) in real time. The system provided petrophysical and geomechanical evaluation with well inclinations greater than 50° in 16-ppg oil-based mud.

T1 and T2 measurements were acquired with an LWD NMR sensor while drilling and during wiping passes. These measurements provided an additional dimension to differentiate clay-bound water from organic hydrocarbons, with good correlation to existing core data in real time. Reservoir characterization of the Najmah Formation using LWD measurements is currently underway to provide a better understanding of reservoir quality, hydrocarbon potential, and reservoir storage capacity of this unconventional source rock. Acoustic velocities play an important role as input to geomechanical information, including the stress regime, principal stress orientation identification, and rock moduli estimation. An azimuthal acoustic tool measuring shear velocities at 360° around the borehole provides answers for the first two attributes. Estimation of formation rock moduli requires accurate acoustic properties and density log inputs, as provided by high-frequency sonic and azimuthal density measurements.

In wells above 60° inclination, it becomes almost impossible to run wireline logging, thus LWD quad-combo with a high-frequency azimuthal acoustic tool is a viable solution for this environment. Additionally, it is an advantage to run LWD while in drilling mode to save rig time and optimize well construction costs.
Orcutt Field Thermal Diatomite Case Study: Matrix Flow Cyclic Steam Injection in the Careaga Lease, Santa Barbara County, California
Authors: Elias Ramon , Medizade Mason
Published: April 2022

This study updates a case history presented in 2013 (SPE 165321-MS) involving cyclic steam stimulation (CSS) in Santa Maria Energy's (SME) opal A diatomite project in the Orcutt field, Santa Barbara County, California. Recent steam injection data from a newer deviated CSS producer drilled in 2019 on 1.2 acre spacing situated immediately north of the original 20-vertical well project is analyzed and discussed. Oil is produced from the project using matrix flow steam injection.

Discussed is the continued success seen with steam injection tracking and monitoring using modified Hall plots and their derivatives. Matrix flow is validated and enables simple analytical calculations to be used for determining a host of parameters including steam zone flow capacity, kh, steam injection rates that avoid formation parting, and the zone of endangering influence (ZEI) needed for UIC approvals. Evidence of pore dilation and unavoidable skin effects are also discussed. Modified Hall plots provide an alternative method for determining the formation parting flow rate (FPR) instead of the formation parting pressure (FPP) since step-rate tests for pressure are not reliable (SPE 169513-MS). An actual CSS well case history is used.

This study shows there to be a wide range of diatomite steam zone injection conditions that do not cause parting or fracturing of the diatomite by steam. The real -time Hall plots used to continuously track and monitor safe CSS steam injection also provide valuable insights as to how injection zone properties change as the project matures. The project monitoring protocols originally described in our 2013 paper continue to be used with safe and reliable outcomes confirmed by thousands of successful project CSS injection operations. This project has not produced any out of zone break outs since the start of steam injection in 2009.
Project Case Study: Online Sand Removal System for Water Tanks
Authors: Wolf Mark E. , Geersen Jonathan , Rojas Ruben , Saadipour Shahab
Published: April 2022

The Elk Hills and Buena Vista Field, located in the southwest San Joaquin Valley, have over 3000 active wells producing from various reservoirs which are predominantly characterized by a deep marine siliceous shale, or sandstone lithology and are overlain by a shallow marine, tidal-influenced sandstone lithology. Wells are completed as slotted liner, gravel pack, case and perforation, with some wells hydraulically fractured or acid stimulated, producing between 0 and 4000 barrels of liquid per day and 0 to over 1 million standard cubic feet of gas per day. With the variety of reservoirs, and fluid compositions, produced solids and scales accumulate in the surface facility equipment, limiting capacity of vessels, tanks, overall fluid handling capacity and water quality.

Dehydration facilities and water treatment facilities experience frequent buildup of sand and scales in the water tanks negatively affecting separation performance and increasing maintenance costs related to tank cleanouts and pump repairs. Excess solids also impact water injectivity and subsurface performance.

California Resources Corp (CRC) reviewed options for reducing operating costs, maintenance downtime, and risks from human exposure during maintenance and chose to implement an online sand removal system based on vortex fluidizer technology.

This paper discusses implementation of the project and will review major considerations and important decisions made during project design and implementation. The paper will highlight case studies from the literature supporting a decision to select flexible HDPE in lieu of stainless steel and carbon steel for both internal and external slurry lines as a cost saving measure. Special considerations for design of slurry piping and pumping systems will be addressed.
Analyzing X-Ray CT Images from Unconventional Reservoirs Using Deep Generative Models
Authors: Perez Claro Yulman , Dal Santo Niccolo , Krishnan Vignesh , Kovscek Anthony
Published: April 2022

Characterization of rock samples is relevant to hydrocarbon production, geothermal energy, hydrogen storage, waste storage, and carbon sequestration. Image resolution plays a key role in both property estimation and image analysis. However, poor resolution may lead to underestimation of rock properties such as porosity and permeability. Therefore, improving the image resolution is paramount. This study shows the workflow for 2D image super-resolution processes using a Convolutional Neural Network (CNN) method. The rock samples used to test the networks were three unfractured Wolfcamp shales, a Bentheimer sandstone (Guan et al., 2019), and a Vaca Muerta (Frouté et al., 2020) shale. These samples were imaged with a clinical Computed Tomography (CT) scanner (100's µm resolution) as well a microCT scanner (10's µm resolution). This established training, validation, and test data sets. The deep learning architectures were implemented in Matlab 2021b. The network performance is calculated using two metrics: i) pixel signal to noise ratio (PSNR) and ii) structural similarity index method (SSIM). In addition, porosity values on the image data sets are presented to illustrate their relevance. Training options and different strategies for network tuning are also discussed in the results section. Results illustrate the potential for AI to improve the resolution of CT images by at least a factor of 4. This level of improvement is essential for resolving fractures, other permeable conduits in impermeable shale samples, and shale fabric features. We outline a pathway to greater improvement of resolution.
Latest Technologies and Methods for Carbon Capture and Underground Gas Storage
Authors: Aydin Hakki , Yegin Cengiz , Nagabandi Nirup , Temizel Cenk
Published: April 2022

Carbon capture and underground gas storage technologies have been an area of significant focus in oil and gas industry over the past few decades. They reduce the carbon footprint of oilfield activities and have a critical role in the energy transition efforts by the industry. This study focuses on conducting a thorough review of literature related to latest advances in carbon capture and underground gas storage methods including real-field applications of these technologies. The future potential of these technologies in enabling the oil and gas industry to achieve its ESG goals are also discussed.

This chapter examines carbon capture and underground gas storage (CCS) technologies and summarizes various types of CCS techniques such as post-combustion, pre-combustion, and oxyfuel combustion. It describes the important operational principles, efficient methods of technology deployment, and best practices to ensure positive project economics. Additionally, the use of the CCS as a method to enable enhanced oil recovery (EOR) in the oil and gas industry, as well as application areas and challenges faced in the use of CCS in oilfield operations, are discussed. The latest advances in this technology from a global perspective and the future potential of CCS as a critical driver in helping achieve sustainability goals for the oil and gas industry are summarized.

Critical factors related to the application of the CCS, including the key decision variables to be considered while implementing projects that uses these technologies are provided to be used as a guideline in decision making. Examples of the use of these technologies to improve the sustainability of oil and gas production operations are provided, as well as the benefits, drawbacks, and challenges in scaling up the use of these technologies in fields are discussed in detail.

This study closes the gap in the literature by providing a comprehensive overview of the current status of the CCS technologies and guidelines for their implementation in oil and gas fields. It serves as a single source of information to the oil and gas industry, while laying out relevant data and information related to the CCS technologies, highlighting the latest advances in their application and the future of these technologies from a global perspective.
Prediction of Pressure and Temperature Profiles and Hydrate Formation Region in ESP-Lifted Natural Gas Hydrate Wells
Authors: Ping Xiaolin , Han Guoqing , Cen Xueqi , Bai Zhenqiang , Zhu Weitao , Peng Long , Ma Bojiaer
Published: April 2022

Depressurization is one of the most effective methods in natural gas hydrate (NGH) production trails. Meanwhile, electric submersible pumps (ESP) are mostly employed to depressurize natural gas hydrate reservoirs. The profiles of temperature and pressure in the wellbore have an important impact on the secondary formation of hydrate. The pressure increase caused by ESP system and the low temperature on seabed will increase the risk of secondary hydrate formation in gas hydrate production wells. In contrast, the temperature rise generated by motor and the heater added to the ESP string will decrease the risk of secondary hydrate formation. Therefore, it is necessary to evaluate the risk of gas hydrate formation in ESP-Lifted gas hydrate production wells.

Based on the world's first offshore methane-hydrate production-test system in Nankai Trough comprised of an ESP with a gas-separation system and a heater, a gas-liquid two-phase flow model coupling temperature and pressure is established to predict the formation region of hydrate in dedicated gas/water lines and mixing-delivery line. The influences of operating frequency of ESP and power of heater on temperature and pressure are analyzed in the proposed model in this research.

The results of the proposed model are verified by comparing with the first offshore gas hydrate production test in the Nankai Trough. The temperature limit for gas hydrate formation inside the well can be estimated with the proposed model and phase equilibrium model to predict the risk of secondary hydrate formation in ESP-lifted wells.

In this paper, it is demonstrated that the highest hydrate formation risk is above the discharge location of the pump and the middle and lower part of the seawater section of the water drainage line. Increasing the operating frequency of ESP and power of heater can reduce gas hydrate formation in gas hydrate wells. Besides, injection of chemical inhibitor can eliminate the risk of hydrate reformation. The results of this research can lay the foundation for flow assurance, ESP designs and production optimization of natural gas hydrate production wells.
Economic Modeling of Carbon Capture and Sequestration Projects Utilizing Re-Purposed Onshore California Wells and Infrastructure
Authors: Yang Siho , Paul Donald Lee
Published: April 2022

At present, approximately 37,000 out of 110,000 oil and gas wells in onshore California are classified as ‘idle’ - they have not been producing hydrocarbon or water, including EOR, for two consecutive years without abandonment. In this context, we examine whether operators retaining those current or potentially future idle wells could economically re-purpose their assets for a carbon storage operation. Such an approach would potentially defer the eventual decommissioning, abandonment, and remediation costs of these assets.

This study models the economics of a fully integrated system from source CO2 capture through subsurface storage for a thermal steam operation. The model workflow developed in this paper is as follows: capture carbon dioxide from steam co-generation plants in heavy oil steam injection fields in the San Joaquin Valley, delivering it via pipeline to selected idle producing or injection wells, converting those wells into carbon dioxide injectors, and finally injecting and monitoring for sequestration. The well re-purposing process would isolate the formerly produced hydrocarbon interval and re-complete in the overlying saline aquifer interval to be used for CO2 sequestration.

The fundamental difference of project economics between hydrocarbon production and carbon capture and sequestration is the regulatory and policy-defined financial incentives. In California, those consist of three major elements: Section 45Q tax credits by the federal government, low-carbon fuel standard (LCFS) credit by the State of California, and cap-and-trade emission allowances. The economic model shows that two factors, LCFS credit price and the cost of carbon capture systems, comprise the most significant proportion of impact on economic feasibility. To achieve the breakeven IRR of 10%, first, LCFS eligibility of the CCS project for a co-generation plant should be improved, and credit price needs to remain at least at the current level. On top of that, the expected increase in future LCFS credit prices and cap-and-trade allowance as potential revenue in an opportunity cost context would enhance economic performance. Secondly, the most plausible, the CAPEX of carbon capture systems at steam co-generation plants would need to be reduced to the lowest cost benchmarks currently seen in process plant implementations.

This paper can be viewed as a starting point to stimulate examination of carbon capture and sequestration project options by both operators managing end-of-field life producing assets, as well as State of California regulatory agencies pursuing carbon reduction as part of the state's larger energy transition strategy.
A Numerical Model Study of Scale-Dependent Fluid Flow and Storage Systems in Unconventional Reservoirs
Authors: Reichhardt David , Hoffman B. Todd
Published: April 2022

Unconventional reservoirs hold vast amounts of untapped hydrocarbon resources; however, given current production capabilities and our understanding of unconventional reservoir production mechanisms only 5% to 10% of these hydrocarbons are typically recovered. The ability to recover additional hydrocarbons from unconventional reservoirs is dependent on an improved understanding of the production mechanisms which are a function of the complex lithology and reservoir fluid systems, and the interactions between these systems.

The lithology and fluid systems present in most unconventional reservoirs result in production from several scale-dependent fluid flow and storage systems, or depletion systems, that combine to contribute to the total production. These depletion systems can include matrix level features defined by pore size, natural fracture systems within the matrix, and hydraulic fractures in addition to the traditional depletion systems defined by stacked pay. The fluid phase behavior within these systems also has a scale dependence that must be taken into consideration. As a result, the individual systems tend to deplete at different rates.

The purpose of this work is to describe the production mechanisms in terms of the lithology and reservoir fluid interactions. By using numerical simulation to systematically isolate production from individual depletion systems, the role and significance of each system is quantified.

A numerical model was developed to simulate the contributions to total hydrocarbon production from multiple depletion systems. Fluid tracers were placed within each depletion system to isolate the individual system production.

The results show the stage of production when each depletion system is active and the associated hydrocarbon volumes. For example, the hydraulic fracture system provides most of the initial production, but contribution from the matrix and natural fractures quickly overtakes it. Composite production curves were developed by combining the simulated production contributions from each depletion system, highlighting the influence the different systems have on the total production.

This paper provides insights into the production contributions from multiple depletion systems found in many unconventional reservoirs. Understanding the roles that the different depletion systems play on production will lead to better well spacing, reserve estimates, and improved reservoir production practices including enhanced oil recovery methods that may be optimized to target the most promising aspects of the reservoir.
Data-Driven Discovery of Physics for Reservoir Surveillance
Authors: Nagao Masahiro , Sun Wenyue , Sankaran Sathish
Published: April 2022

Understanding well production performance in hydrocarbon reservoirs in a timely manner is essential for closed loop reservoir management, improving operational efficiency, and maximizing value. It is desirable to have a robust and scalable method for estimating well productivity index and reservoir pressure, which can be applied in a practical and automated manner. Traditional surveillance methods are interpretive and do not scale for manual surveillance of either large fields or those with large data volumes. In this work, we propose a machine learning approach to discover physics that can be built using routine field measurements (downhole pressure and rates) and used for estimating well productivity, real-time production rates, pressure depletion and short-term forecasts.

The relationship between rates and pressure evolution is guided by nonlinear diffusivity equation. We seek methods for projecting the nonlinear state problem onto a linear (or weakly linear) space based on several methods – namely, time delay embedding, physics-inspired features, and dynamic mode decomposition (DMD). This augments the information contained in the system state with measurements of the state history. We also developed a background signal decomposition method to extrapolate routine buildup pressure data to estimate average reservoir pressure based on two different methods – optDMD (optimized DMD) and SINDy (sparse identification of nonlinear dynamics).

The background signal decomposition method was validated on several heterogeneous reservoir cases to estimate average reservoir pressure from buildup data, where our results outperformed traditional methods. In cases where multiphase flow meter rates were available, the proposed hybrid reservoir model was used to predict pressure with a virtual shut-in simulation. By offsetting the need for shutting in the well and associated production deferment, the virtual shut-in predictions were used to estimate reservoir properties. The results were validated on both pressures and pressure derivatives, typically used for pressure transient analysis. Next, we observed that the model can be used to provide accurate multiphase production rate forecasting (virtual metering) by reversing the model inputs and outputs. Based on the hybrid model, a workflow for tracking reservoir properties was developed to capture the decline of average reservoir pressure and productivity index, which was applied to both synthetic and field cases with reasonable accuracy.

The proposed hybrid reservoir modeling approach automates routine surveillance at field scale with high computational efficiency. By learning from natural operational variations continuously, it decreases planned downtime and associated production loss. It also enables detecting well performance issues much earlier to plan timely remedial actions. It provides a practical way of combining data-driven methods with our understanding of physics, while keeping the analysis interpretable and enabling closed loop reservoir management.
Evaluation of Stresses Alteration on the Productivity of Marcellus Shale Horizontal Well
Authors: El Sgher Mohamed , Aminian Kashy , Ameri Samuel
Published: April 2022

The objective of this study was to investigate the impact of fracture properties and mechanical rock properties on stress changes and, consequently, the productivity of a horizontal Marcellus Shale well with multi-stage fractures.

The available advanced technical information from the Marcellus Shale horizontal wells at MSEEL site provides an opportunity for an integrated analysis to gain insight into the impact of stresses changes. When the pore pressure decreases due to depletion in a reservoir, the increase in effective stress results in a reduction in fissure permeability and porosity that affects cumulative gas production. In this study, the Mohr-Coulomb model, the foremost common model, was utilized to account for geomechanical effects.

A reservoir model which incorporated the gas storage mechanisms inherent in shales, i.e., matrix porosity, natural fracture porosity, and adsorption was developed. The mechanical properties of the shale were estimated from the available well log data. The core, log, completion, stimulation, and production data from the wells located at the Marcellus Shale Energy and Environment Laboratory (MSEEL) were utilized to obtain the formation and completion properties for the model. Barton Bandis Model was then implemented in the reservoir model to investigate the closure of the natural fractures during production. The impact of the stress changes was then investigated by performing parametric studies.

The geomechanical effects such as compaction and subsidence increase as the length of the hydraulic fracture increases. Furthermore, the higher the initial hydraulic fracture conductivity is, the more significant geomechanical effects become. Both of these are the results of greater pressure depletion. Additionally, as the pressure drawdown increases (wellbore pressure decreases), geomechanical effects increase. Mechanical rock properties (Young's modulus and Poisson's ratio) also influence the geomechanical effects. As Young's modulus of the rocks decreases, cumulative gas production increases due to compaction drive.
Visualization of Liquid Slugging Using Detailed, High-Quality Pressure Monitoring
Authors: Gordon Ryan David , Ito Tokunosuke , Vekved Kerry Laverne
Published: April 2022

Liquid slugging in gas gathering systems is a costly problem. It is difficult to manage because it is hard for pipeline operators to know where and when slugs form and how they move. This paper demonstrates how detailed pressure measurement across pipelines in a gathering system can be used to visualize slug formation and movement, thereby enabling pipeline operators to better manage slugging issues at facilities.

Pressure monitoring devices, based on an internet of things (IoT) architecture, were installed on the main branch lines feeding the inlet separator of a gas gathering system. Each device continuously captured, stored, and delivered high-quality, time-synchronized, per-second pressure measurements to a cloud-based data service. Detailed pressure data from several days of normal operations was integrated with operational data that showed slug arrival times and volume at the inlet separator, along with timing of pigging operations. The data was assessed for correlations between slugging activity and changes in pressure patterns along each line. Pigging operations were optimized based on the results.

Clear correlations were observed between slugging events and changes in differential pressure over time along a given branch line. By recognizing the pressure pattern associated with slugging events, the location and timing of liquid slug formation in the lines of the gas gathering system were determined. Pressure patterns were distinct and could be alarmed on to provide early notification of a slugging event. The magnitude of differential pressure was found to be loosely correlated to slug size in most branch lines. The impact of pigging on pipeline operations could also be visualized as changes in pressure patterns. This visualization enabled pigging to be optimized to reduce liquid build-up in branch lines that contributed to large slugging events. The optimization resulted in a reduction in labor costs for managing slugging issues such as compressor shutdowns and flooding the inlet separator as slugging events became smaller and less frequent. It also resulted in a sustained production increase of 20% for wells feeding one of the most problematic branch lines as line pack pressure was reduced enough to impact productivity.

This case study demonstrates a new way for pipeline operators to visualize slug formation and movement in their gas gathering systems as changes in pressure along a pipeline. Once visualized, slugging can be better managed, potentially leading to production increases, reduced costs, or both. The use of detailed pressure monitoring to visualize fluid dynamics within pipes or process equipment may have many applications in the oil and gas industry for enabling operational improvements.