bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production Forecasting in Tight Gas Reservoirs Using Long Short-Term Memory Methods (LSTM)
Authors: Qoqandi Afrah , Alfaleh Omar , Ramadan Moemen , Odi Uchenna 
Published: March 2023

Abstract
Forecasting the estimated ultimate recovery (EUR) for extremely tight gas sites with long-term transient behaviors is not an easy task. Because older, more established methods used to predict wells with these characteristics have shown important limitations, researchers have relied on new techniques, like long short-term memory (LSTM) deep learning methods. This study assesses the performance of LSTM estimations, compared to that of a physics-based reservoir simulation process.
With the goal of obtaining reliable EUR forecasts, unconventional tight gas reservoir data is generated via simulation and analyzed with LSTM deep learning techniques, tailored for sequential data. Simultaneously, a reservoir simulation model that is based on the same data is generated for comparison purposes. The LSTM forecasting model has the added benefit of considering operational interventions in the well, so that the machine learning (ML) framework is not disrupted by interferences that do not reflect the actual physics of the production mechanism on well behavior.
The comparison of the data-driven LSTM deep learning model and the physics-based reservoir simulation model estimations was performed using the latter framework as a benchmark. Findings show that the AI-assisted LSTM model provides predictions similarly accurate to the ones estimated by the physics-based reservoir model, but with the added capability for long-term forecasting. These data-driven EUR models show great promise when analyzing unusually tight gas reservoirs that feature time series well information, which can improve estimations about recovery and point engineers towards better decisions regarding the future of reservoirs. Therefore, exploring deep learning methods featuring varying types of artificial neural networks in greater detail has the potential to significantly benefit the oil and gas sector.
When compared to other machine learning methods, novel deep learning techniques have advantages that remain underexplored in the literature. This paper helps fill this gap by providing a valuable comparison between older prediction methods and new estimation simulations based on neural networks that can predict long-term behaviors.
Magnetic Sensors for Navigation of Untethered Downhole Robots
Authors: Seren Huseyin , Deffenbaugh Max , Larbi Zeghlache Mohamed , Bukhamseen Ahmed 
Published: March 2023

Abstract
Following the 4IR revolution, automation of oil and gas operations became a prime target. Various efforts have been put forward to create autonomous downhole tools which can increase the time and cost efficiency while reducing health and safety hazards. Navigation of the autonomous tools remains as one of the high barriers preventing these technologies from becoming available. This manuscript presents three new solutions we developed for our untethered autonomous logging tool to overcome this barrier.
To increase the environmental self-awareness of downhole robots, we developed two technologies that will work together. The first technology is a low power miniaturized casing collar locator where a milimiter-size magnetometer chip and two 1-inch rod magnets are employed. The second technology is based on 1-D feature matching of residual magnetic fields generated by the steel casings. Here, two magnetometers are placed on the tool with a known separation along the direction of the motion. A correlation algorithm calculates the position and speed using the magnetic field logs.
The low power miniaturized casing collar locator is placed on a wireline tool for the proof of concept demonstration. The tool was run in a water filled test well with 1450 feet depth. Decentralizers were used to keep the tool close to the casing wall. Clear peaks were observed at regular intervals. The detection depths were compared to a casing collar log run by a logging service company and one to one match was observed. The 1-D magnetic feature matching technology is demonstrated first by collecting residual magnetic field data from the same test well with a wireline tool. The collected signal was shifted in space and noise is added to mimic the difference with a second magnetometer. The matching algorithm was used to successfully find the shift between the two signals in time along the full log. This helped to estimate the speed of the tool which is used to calculate the position. Using information from the presented technologies, along with the data from other environmental sensors such as pressure and temperature will provide precise location that were not available before. The certainty will be improved by employing a Kalman filter that will integrate the sensor inputs.
As in all autonomous vehicles, increasing the environmental self-awareness of autonomous downhole tools carries high importance for intelligent decision-making, successful and safe operation. Technologies fo surface applications, such as global positioning system, and radar may not be suitable for downhole environment. Therefore, new sensing technologies as we present here will accomplish these jobs for the robots operating below the surface.
Integrated Approach for Water and Energy Management in a South of Oman Cluster
Authors: Jabri Arwa , Sawafi Marwan , Sulaimani Rihab , Ghailani Taher , Hugonet Vincent , Abri Moh'd , Hinai Suleiman 
Published: March 2023

Abstract
Produced water is an inevitable by-product from oil wells and the challenge lies in how to best manage it both economically and environmentally. A large cluster in the South of Oman with around 30 fields and more than 2000 active wells has a daily water production rate of more than 100,000 m3/d. Management of this produced water is crucial in prolonging oil production and maximizing recovery from these fields. A certain strategy is being followed where different initiatives are taken to manage the produced water.
The water management strategy been followed is to Reduce, Relocate and Reuse, the 3 Rs. The 3 Rs strategy has been implemented in the cluster by taking the initiatives below:REDUCE: Implementation of Autonomous Inflow Control Valves Technology: which has resulted in an average water reduction of 70% while increasing the oil production by 10% where implemented. It has also resulted in lower water management costs and lower Green-house Gases intensity.REDUCE: Frequent Well-by-Well economic evaluation: where all oil wells are screened in terms of economical oil cut-off breakeven value with respect to well operating cost and then re-visiting the identified wells. The economic screening also accounts for CO2 penalties to drive GHG and energy efficiency. As well as continuous waterflood optimization by carrying out structured reviews, to promote high efficiency injectors and demote low efficiency injectors.REUSE: Increasing waterflooded reservoirs’ throughput rate: less Deep-Water Disposal and hence less power consumption for DWD pumps and lower fields’ Greenhouse Gases intensity.REUSE: Water re-allocation and use for agriculture/biofuel and other industrial use building on successful projects across Oman. This type of use provides great enablers for deep water disposal phase-out, hence positive impact on GHG & energy management.
Taking such initiatives has resulted in reducing Deep Water Disposal, optimization of rates (balancing offtake/intake) as an output of the Well-by-Well economic evaluation and an increase in oil production as an output of technology implementation. This has also led to reducing Greenhouse Gases Emissions, minimizing energy inputs, and reducing treatment costs since these initiatives are directly linked to Energy Management.
Effects of Temperature and Rate-Dependent Mud Cake Buildup on Wellbore Stability in Multi-Permeability Formations
Authors: Liu Chao , Phan Dung T. , Abousleiman Younane N. 
Published: March 2023

Abstract
In this work, we use the theory of multi-porosity multi-permeability porothermoelasticity to derive the analytical solutions of pore pressure and stresses for an inclined wellbore, accounting for a rate-dependent mud cake buildup on the wellbore wall. The solutions are further combined with the Hoek-Brown shear failure criterion and a tensile failure criterion to calculate the critical collapse and fracturing mud weights. We choose a naturally fractured rock formation as an example to demonstrate the coupled effects of temperature, mud cake, and the formation's dual-porosity dual-permeability on wellbore stability. We show that drilling mud with a lower temperature than the rock formation results in differential contraction of the solid and pore fluid constituents and leads to significant alteration of pore pressure and stress distributions. Additionally, a low-permeability and thin mud cake can considerably increase effective tangential stress. Natural fractures also alter the pore pressure and effective stress distributions because of fractures’ higher permeability than the rock matrix. Both wellbore cooling and filter cake buildup decrease the collapse mud weight. Natural fractures have significant weakening effects, increasing the collapse mud weight and decreasing the fracturing mud weight. This work provides the first solutions for wellbore stability analysis, considering together the time-dependent filter cake buildup, thermal effects, and formation's multi-porosity multi-permeability.
Rock Mechanical Characterization of Shale-Drilling Fluid Interactions to Mitigate Borehole Instability Problems
Authors: Alqam Mohammad , Amanullah Md , Algarni Salem , Almakrami Adnan 
Published: March 2023

Abstract
Borehole instability is one of the biggest problems faced by the oil and gas industry when drilling shale formations, mudrocks, marl, or a combination of them using water-based muds.
The physio-chemical interaction of water-based drilling muds and the rock formations along with their micro and macro scale mechanical degradation are some of the root causes for instantaneous and time dependent borehole instability problems. Though there are comprehensive studies of physio-chemical aspect of shale-drilling fluid interactions, only a few studies are available, that describe the rock mechanical aspect of shale-drilling fluid interactions. Hence, there is a need for a compressive study of the rock-mechanical aspect of shale-drilling mud interactions. This R&D will concentrate on the testing and evaluation of the geo-mechanical aspect of shale-drilling fluid interactions by conducting rock mechanical testing of original shale cores, water saturated shale cores and two water-based muds saturated shale cores for comparative assessment of the rock-fluid interactions effect on the mechanical properties of reactive shales/mudocks.
This paper describes the rock mechanical diagnostic signatures of rock-fluid interactions that were related to instantaneous and time dependent borehole instability problems. This study will provide a tool for field's engineers to predict the nature of the borehole instability problems and provide appropriate technical guidelines to the mud engineers and drilling fluid consultants to reduce the probability and the likelihood of creating instantaneous and time dependent borehole instability problems.
Identification and Mapping of Gas Reservoir Bitumen
Authors: Al Solial Ali J , Shaikh Aijaz , Idrees Abdullah K 
Published: March 2023

Abstract
Reservoirs that have undergone a gas charge after being charge with oil will have oil trapped within the reservoir. The interest of this study is to identify ways to trace that heavy oil, referred to as bitumen, in gas reservoirs from openhole logs along with identifying the controlling parameters on the trapping of this bitumen. The bitumen could be pore-saturating or grain coating.
This paper looked into the petrophysical logging responses from 3 wells with confirmed bitumen at surface as well as thre other wells with matching signatures, for the purposes of mapping. The main logs considered were Resistivity and density-neutron, with formation testing and elemental spectroscopy being used as additional data sources. Thin sections from the cores, were also used to further identify more controlling parameters that might exist.
Regardless of the nature of the bitumen's existence within the pore-space it appears that the main controlling parameters are structural. The investigation of petrophysical signatures lead to minor structural changes within the silt being able to provide a trap for the bitumen charge to accumulate. Use of silt-sand-shale analysis allowed to map the presence of the sub-structures under which the bitumen resides further leading to the fact that bitumen presence in the reservoir is structurly controlled. This does explain why bitumen exists in some areas of the reservoirs and not in others. Moreover, this also explains the generally relative low thickness of bitumen. Mapping the layers and ditrubuting them into 3d space will allow for the prediction of where the bitumen occurs as long as a controlling depth, above which bitumen exists, can be identified. Alternatively, flatting the structure to conditions prior to the development of the current seal can be done to better identify where the bitumen could've been trapped.
Bitumen in deep reservoirs will impact fluid composition and can have impacts on drilling and drilling strategy. Therefore, identifying where the bitumen occurs is of high value to the development of these reservoirs. Further work remains to be done for identification in carbonate reservoirs and potentially further study of more bitumen saturated samples might lead to a better understanding of the phenomenon.
A Novel Chemical Formulation for Heavy Oil Viscosity Reduction and Heavy Oil Displacement
Authors: Chen Shaohua , Han Ming , AlSofi Abdulkareem , Huang Tianping 
Published: March 2023

Abstract
A novel water-soluble viscosity reducer (VR) formulation containing various polyaromatic hydrocarbon structures was designed for effective heavy oil viscosity reduction and heavy oil production by oil displacement. This VR package contains several components, including aromatic groups attached short-chain water-soluble polymers which were synthesized in laboratory, small-molecular aromatic chemicals, non-ionic and cationic surfactants, and rheology modifiers. The designed VR formulation was compatible with the high-salinity water (HSW) using appropriate preparation procedures. The VR solution in HSW yielded a stable emulsion after mixing with heavy oil and the emulsion phase separated subsequently, indicating a good performance in demulsification. The formulation decreased the viscosity of heavy crude oil by 84.2% at a temperature of 50 °C, a VR concentration of 0.2 wt%, and an oil-to-water ratio of 7:3. Micromodel test indicated that the residual oil blocks were effectively replaced by the VR flooding due to the strong emulsification and increased sweep efficiency by heavy oil viscosity reduction. The injection pressure decreased by the VR flooding due to a reduced viscosity of the heavy oil. The initial water injection increased the heavy oil production by 15% only, while the following VR flooding further enhanced the heavy oil production by 26% and the post water injection exhibited a limited effect on enhanced oil production by 4%, as obtained from the core-flooding test using a heavy oil saturated carbonate core.
Transforming Challenges into Opportunities to Design Fit for Purpose Long Term Polymer Injectivity (LTPI) Pilots in Umm Gudair Minagish Oolite Reservoir, West Kuwait
Authors: Khan Mohammad Yunus , Kamal Dawood , Al-Mayyan Haya Ebrahim Ali , Pradhan Akshaya Kumar , Eadulapally Satish Kumar , Al-Murayri Mohammed Taha 
Published: March 2023

Abstract
Umm Gudair Minagish Oolite is a highly heterogeneous reservoir with intermittent micritic units forming low permeability barriers to fluid flow. Based on screening/lab study, the polymer or surfactant-polymer flooding was proposed using normal 5 spot injection pattern. KOC decided to test only polymer flooding because of cost considerations. This study is to design fit for purpose long-term polymer injectivity (LTPI) pilot using produced water (salinity 230000ppm) with the objectives of testing injectivity, adsorption, breakthrough, resistance factor and response time within 6-12 months.
Numerical simulation and economic modelling was used for this evaluation to explore various novel strategies. Various parameters were optimized to design Fit for Purpose LTPI pilot configurations using high salinity produced water. The laboratory experiments were conducted in conjunction with reservoir simulation to confirm the technical viability of polymer flooding using high-salinity water. In this study, we discuss existing challenges and how the same was transformed into opportunities by optimizing various parameters such as number of wells, well spacing, well location, perforation layer for injectors and producer and the economics to meet pilot objectives.
The simulation results show that normal 2-spot injection pattern (2 injectors and 1 producer) with 80m well spacing and perforation in B-zone is a suitable solution for LTPI pilot within given time. Based on the above plan, one injector was drilled near the existing producer. The recent gyro survey demonstrated shifting of the sub-surface locations of both the producer and injector, thereby altering the well spacing. Further simulation incorporating the new locations indicated that the pilot would not meet the objectives within the piloting duration of 6 months because of shifting. Surface constrains hindered the shifting of drilling location for the second injection well to maintain 2-spot injection pattern. To overcome this challenge, additional simulation works performed to plan and drill the second injector well near another existing producer at 80m well spacing in a different area to test different rock types. Both LTPI pilot designs show higher incremental cumulative oil over water flood, faster polymer breakthrough (∼1 month), faster polymer response and oil peak within 6 months. In addition, using high salinity produced water for polymer flooding is expected to reduce piloting cost and increase operational efficiency by reducing operational problems associated with treatment and handling of less saline water.
Technological and Engineering Evolution to Successfully Drill Long and Highly Deviated S-shape Wells
Authors: Aljuzayri Mohammed , Bansal Sarvodaya , Ponomareva Daria , Franco Nata , Corona Mauricio , Levario Jesus 
Published: March 2023

Abstract
Drilling S-shape wells across highly heterogenetic formations and at high inclination is particularly challenging due to increased risks, such as differential sticking, total losses and well control. This often leads to poor performance, stuck incidents, fishing operations and sidetrack. This paper aims to share the technological evolution and engineering approach to well planning and operations execution to deliver S-shape wells with long step out and high deviation.
A thorough review of operational risks and associated non-productive time was performed in each hole size, namely 16" and 12". This combined with a crescent step-out, due to surface location limitations and production requirements, significantly impacted performance. Comprehensive geological and offset well analysis were put in place to select the best well design and trajectory with focus on risk reduction and outperformance. The main contributing factors to achieve that were divided into different categories: bottom hole assembly (BHA) design and latest directional drilling technology; drilling fluid selection and bridging strategy; casing running considerations; and cementing design.
Following the new engineering approach and technology deployment, over 30 S-shape wells have been delivered with various step-out lengths (maximum of 3,500 ft) and tangent inclinations (maximum of 32°). Flowless operations, record wells and longest step-out S-shape were delivered throughout project life. Trajectory planning, optimized light BHA, combined with autonomous directional drilling technology and dynamic survey-while-drilling service were crucial to minimize plan complexity, stuck pipe risk whilst meeting the desired targets. Fit-for-purpose drilling fluid design and bridging strategy further helped on differential sticking and downhole mud losses prevention. For the casing to reach the bottom, it was also essential to have low friction factors through centralization stand-off optimization, lubricity enhancement and customized running schedule. Light cement slurry design and cementing job remote monitoring minimized equivalent circulating density (ECD) while ensuring solid cement bond and well integrity with real-time top of cement identification.
The gradual evolution of engineering and technology deployment based on well-customized risk assessment led to drilling the most challenging S-shape wells and record-breaking performance in the gas field in the Middle East. This strategy will serve as a reference for service companies and operators to accelerate learning curve and achieve similar step change operations.
Drilling Monitoring System: Mud Motor Condition and Performance Evaluation
Authors: Koulidis Alexis , Abdullatif Mohammed , Ahmed Shehab 
Published: March 2023

Abstract
Condition monitoring of bottom hole assembly (BHA) is essential during the different lifecycle stages of the drilling process, whether during the planning, implementation, or post-job failure analysis. Mud motor condition evaluation can assist in preventing mud motor damage and increasing drilling efficiency. This paper aims to develop a monitoring system that combines field data, data analytics and physics-based modelling to evaluate mud motor condition and performance.
The drilling monitoring system is a set of modelling and analysis tools that utilize actual drilling data, power section performance data and drillstring design to recreate the drilling process.
An unprocessed drilling dataset is required to assess the drilling operations (rotating or sliding mode, rotating off-bottom, backreaming, connections) and reconstruct the borehole trajectory from the measured survey and duty cycle (rotating and sliding mode). Interaction of the BHA and the borehole generate side forces and bending moments along the length of the BHA that are evaluated at each depth increment during the drilling process. Generated power and efficiency of the mud motor are calculated and incorporated into the dynamic simulation.
The case study investigates two motor runs in vertical and inclined sections. Dynamic modelling and extensive data analytics assist in visualizing and correlating the input and output variables during the drilling process. The continuous evaluation of the differential pressure on the motor is the primary parameter that is investigated. The motor condition is established with a continuous wear-off test while drilling and correlation matrices to indicate a constant motor state for 135 hours.
The system accurately monitors the motor's operating efficiency, with the additional advantage that the mud motor and drill bit performance are differentiated. Precise adjustments of the drilling parameters for the optimum depth of cut positively impact motor efficiency.
In addition, an interesting observation shows that accurate modelling of downhole and surface torque provides significant insights regarding bit state. The results demonstrate that with the current methodology decrease in drilling efficiency is detected and is associated with bit wear.
The work enables the evaluation of the mud motor condition and performance by utilizing a monitoring system and actual drilling data. The drilling monitoring system is a modelling analysis tool that can provide continuous feedback to the drilling operators about the condition of the BHA. Hence, it enables a real-time optimization process to manage mud motor condition and enhance drilling efficiency.