bluuebunny/crossref_metadata_2025 huggingface dataset:
A Data-Driven Model for Bound Fluid Prediction in Carbonate Reservoirs
Authors: Alshuwaikhat Ali , Albalawi Ghadah , Alshammasi Laila , Meridji Yacine
Published: March 2023

The objective of this paper is to develop a machine learning workflow in order to replicate the Nuclear Magnetic Resonance (NMR) bound fluid volumes utilizing triple-combo data. The developed model is to overcome the logging operations challenges and to enhance the petrophysical formation evaluation in carbonate reservoirs and most importantly a proper completion design to avoid free water bearing zones (Dodge et al 1998).

The presented data-driven model is based on artificial intelligence (AI) and data mining techniques. In order to select the required data input, many logging parameters were investigated and several iterations with different sets of parameters were attempted to identify those with the most impact on bound fluid volume prediction. Henceforth, the iteration with the lowest root mean square error (RMSE) is to be selected. The model was trained, calibrated and validated to accurately predict the NMR bound fluid volume. The main purpose of this study is to draw attention to the capabilities of the artificial intelligence techniques to provide logging responses with excellent match compared to the measured logs in the event that operational complexities or budget constraints arise.

Several wells with excellent data quality were selected from the same field to build and test the RF (Random Forest) model. 56% of the wells were used for training and the remaining 44% were kept for blind tests. During the modeling process, several iterations were attempted to identify what was really driving the BFV prediction, the best model was chosen based on the lowest RMSE (Root Mean Square Error). The model statistics indicated the combination of resistivity, density, neutron, GR, produced the best model with lowest RMSE = 0.78 pu (porosity units). The model was later deployed to the remaining blind test wells, the results were of excellent accuracy when compared to the measured log data with error difference way below the acceptable industry standard of 1 pu. With accurate BFV prediction, free water zones can now be identified and avoided during completion. This methodology will help operators reduce risk, maximize production without straining their budget to acquire NMR logs in every horizontal development well, or even attempt formation tester samples unnecessarily.

Implementing this new machine learning methodology will help in increasing the confidence in petrophysical analysis and reservoir management decisions, as well as optimizing the logging runs. This results in cost savings without compromising the quality of the formation evaluation, in addition to minimizing the carbon footprint associated with unnecessary operations.
Fully Coupled Hydromechanical Approach for Flow in Fractured Rocks Using Darcy-Brinkman-Biot
Authors: He Xupeng , Zhang Zhen , AlSinan Marwa , Kwak Hyung , Hoteit Hussein
Published: March 2023

Coupling flow with geomechanical processes at the pore scale in fractured rocks is essential in understanding the macroscopic fluid flow processes of interest, such as geothermal energy extraction, CO2 sequestration, and hydrocarbon production from naturally and hydraulically fractured reservoirs. To investigate the microscopic (pore-scale) phenomena, we present a fully coupled mathematical formulation of fluid flow and geomechanical deformation to model the fluid flow in fractured rocks. In this work, we employ a Darcy-Brinkman-Biot approach to describe the fully coupled flow and geomechanical processes in fractured rocks at the pore scale. Darcy-Brinkman-Stokes (DBS) model is used to model multi-scale flow in the fractured rocks, in which fracture flow is described by Navier-Stokes equations and flow in the surrounding matrix is modeled by Darcy's law. With this approach, a unified conservation equation for flow in both media (fracture and matrix) is applied. We then apply Biot's poroelasticity theory and Terzaghi's effective stress theory to capture the geomechanical deformation. The continuity of the fluid pressure is imposed to connect the DBS equation and the stress-seepage equation. This coupled model is employed to determine the permeability within the microfracture. Numerical results show that this coupled approach can capture the permeability under the effects of solid deformation and multi-scale formation. We develop a fully coupled model to capture the pore-scale flow-geomechanically process in fractured rocks. To our knowledge, the fully coupled framework is developed and applied to characterize fracture permeability at the pore scale in fractured rocks for the first time.
Optimization Model of Fracture Parameters of Shale Gas Fracturing Horizontal Well Based on Genetic Algorithm
Authors: Zhao Xurong , Lan Tian , Tang Zekai , Mu Lingyu , Hu Lianbo , Song Zhigang , Chen Zhiming , Zhou Yicheng
Published: March 2023

Based on a genetic algorithm and field production data, this paper reasonably optimizes the fracture parameters of multistage fractured horizontal wells (MFHWs). First, a mathematical model of MFHWs in shale gas reservoir is proposed under the conditions of variable production and variable pressure. Then, the main factors affecting well production are determined by sensitive analysis. Finally, the production prediction model based on a genetic algorithm (GA) is used to optimize the fracture parameters of the Fuling shale gas reservoir. The results show that in the study area, the number of fractures in typical wells is 10, and the fracture half-length is 90m, and the fracture conductivity is 15.24mD.m. The effective fracture half-length is the main parameter affecting production, so the effective fracture half-length and effective fracture number should be increased reasonably, and the support concentration should be increased properly. What's more, the optimal solution of fracture half-length is 160m, and the optimal solution of fracture number is 8, and the optimal solution of fracture conductivity is 20 mD·m. This paper provides a new idea based a genetic algorithm for optimizing fracture parameters of shale gas wells in the Fuling area.
From Well to Field: Reservoir Rock Porosity Prediction from Advanced Mud Gas Data Using Machine Learning Methodology
Authors: Anifowose Fatai , Mezghani Mokhles , Badawood Saleh , Ismail Javed
Published: March 2023

The utility of advanced mud gas (AMG) data has been limited to fluid typing and petrophysical correlations. There is the need to extend the utility to real-time reservoir characterization prior to wireline logging and geological core description. Our first attempt to predict reservoir rock porosity within a well yielded good result. This study improves on the previous effort by utilizing big data obtained from combining various wells in the study area.

We used machine learning (ML) methodology in the absence of established physical relationship between AMG data, comprising light and heavy flare gas components, and reservoir rock porosity. More than 20,000 data points collected from representative wells were used to prove the concept of predicting the porosity in an interval or section of any well within the study area. Optimized models of artificial neural network (ANN), decision trees (DT) and random forest (RF) were applied to the combined dataset. The combined dataset was randomly split into training and validation subsets in 70:30 ratio. The 30% validation subset simulates a missing well interval or section.

Comparing the results of the ANN, DT, and RF models using statistical model performance evaluation metrics, the RF model outperformed the others. The RF model gave a training and validation correlation coefficient (R-Squared) values of 0.94 and 0.83 respectively compared to 0.36 and 0.35 for the ANN and 0.84 and 0.73 for the DT models respectively. However, the p-value and mean errors show that the models are statistically acceptable. Having showed in a previous research that a multivariate linear regression model could not handle the complexity in the relationship between porosity and the flare gas components, these results have further confirmed the robustness of nonlinear solutions based on the ML methodology. We conclude that the ML approach to predicting reservoir rock porosity from advanced mud gas data is feasible and better results are achievable with more research.

This study has confirmed the feasibility of predicting porosity based on a dataset of combined wells and the huge benefit in extending the utility of AMG data beyond the traditional workflows. This approach is capable of complementing existing reservoir characterization processes in assessing reservoir quality at the early stage of exploration. Future work will investigate the impact of integrating the AMG with surface drilling parameters to possibly increase the prediction accuracy.
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

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

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

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

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

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

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

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

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

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

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.
A Systematic and Comprehensive Approach for Characterizing Capillary Desaturation Curves in Low-Permeability Carbonate Rocks
Authors: Siyal Amaar , Ahmed Shehzad , AlAmeri Waleed , Al-Shalabi Emad W.
Published: March 2023

It is widely recognized that the determination of true residual oil saturation to water (Sorw) is a critical factor in predicting waterflooding performance and implementing enhanced oil recovery (EOR) methods. A particular EOR method will provide a high prospective result if there is an overestimation of Sorw. The concept of capillary desaturation curve (CDC) is used to determine how much amount of oil can be recovered, when implementing a certain EOR technique. The objective of this study is to determine the true residual oil saturation to water (Sorw) for low permeability Indiana limestone outcrops using the centrifuge technique under reservoir conditions and further generate their CDCs. In this work, three carbonate Indiana limestone outcrops with low permeability range (4-8 mD) and representative fluid samples i.e., field oil, formation water, and seawater, were utilized. The CDC was then characterized for carbonate rocks by further reducing Sorw using surfactant flooding where three anionic surfactant formulations with different IFT values were selected. A systematic approach was followed starting with conventional core analysis followed by special core analysis. For the CDC generation via surfactant flooding, three surfactant formulations having different IFT values were selected through a preliminary screening.

This study showed that there is no correlation between initial water saturation (Swi) and absolute permeability for the cores tested. In addition, variations in spontaneous oil recovery was noted among cores within the same range of rock permeability, which indirectly indicates the existence of heterogeneity within each rock. Furthermore, a true Sorw of 20-29% was achieved using the centrifuge method, which was confirmed during the surfactant flooding stage. Additionally, CDC studies indicated that a critical trapping number of 10-4 was achieved for the tested cores, which is higher than most of the reported values of 10−8 to 10−6 in the literature. Accordingly, the complete desaturation of mixed-to-oil wet carbonate rocks is quite challenging since it requires a further increase in trapping number, which could possibly be achieved using ultra-low IFT surfactants. This work presents a systematic and comprehensive approach for determining true Sorw and understanding microscopically trapped oil in carbonate rocks based on CDC. The produced results would be useful in EOR screening for future surfactant flooding pilots in carbonate rocks with low permeability.
An Integrated Experimental Method to Study Multistage Alternating Injection Acid Fracturing in Limestone Formation
Authors: Ren Yonglin , Wang Da , Feng Puyong , Chen Jun , Shao Shangqi , Zhang Wanchun , Cui Bo
Published: March 2023

Multistage alternating injection acid fracturing is one of the emerging acid fracturing techniques to stimulate the carbonate reservoirs. Nevertheless, the previous research on this technology mainly focused on numerical simulation, and there has been little experimental research on it. The etching behavior and mechanism of various acid types and different number of injection stages within the fracture is still unknown.

In this paper, we propose an integrated methodology to experimentally study multistage alternating injection acid fracturing. First, we introduce an innovative acid-etched fracture surface evaluation method to evaluate the acid-etched fracture both quantitatively and qualitatively based on etched fracture surface topography analysis, amount of rock dissolved and a newly defined acid etched channel propagation index, and design a multifunctional core acid etching system to satisfy the requirements of acid etching experiments. Then, we conduct a series of acid etching experiments to optimize the acid types and number of acid stages to create fracture under different core permeability. On the basis of the fracture evaluation, we analyze the mechanism by comparing the etching patterns using different types of acid and fracturing fluid with different number of injection stages. Finally, we further verify the validity of the acid-etched fracture evaluation method through laboratory experiments using a modified fracture conductivity test system to test the fracture conductivity under confining stress ranging from 10~40 MPa.

The following findings can be concluded from the experiment results: similar with previous digital research results, the experiment results show that the number of alternating injection acid stages only slightly influences fracture conductivity and hardly affects the fracture surface etching patterns. Nevertheless, different from previous numerical research results, this experimental study finds that the acid types can strongly affect both the fracture conductivity and etching patterns during alternating injection. Among the four alternating injection combinations, the low viscosity emulsion acid and chelating acid combination shows the lowest conductivity and the lowest channel propagation index, while the cross-linked acid and surfactant based acid combination achieves the highest fracture conductivity and the highest channel propagation index due to their high viscosity and self-diverting properties.

This experimental research provides an integrated experimental method to study multistage alternating injection acid fracturing and its results provide an insight into this technology.
Advanced Research and Development in Unconventional Use of Tracer Technology for EOR and IOR: The Gen Z Tracers
Authors: Chatterjee Monalisa , Toh Sean , Alshmakhy Ahmed , Bigno Yann , Hewitt Paul
Published: March 2023

Over the last few decades, tracers have provided crucial insights on fluid flow behavior assessing reservoir connectivity. For years, they had been viewed as mostly passive molecules that go with the flow of the injected fluid and uncover pathways between injectors and producers. The proposed paper sheds light on some interesting newer frontiers of tracer applications with unconventional uses to gain further flow insight from an oil and gas reservoir.

Although primarily developed for interwell applications, newer and more sophisticated genres of tracers have found their way to assist with well fluid flow behavior. Inflow tracer applications, used for phase flow diagnostics, have been around for a few decades now. However, with several parameters like physical space restrictions, temperature, solid support selection, multi-phase flow, initial surge and target concentrations at play, it was soon realised that an extended lifetime was needed to provide techno-economic benefits during reservoir monitoring. Microencapsulation of tracer molecules is one of the newer developed techniques that has shown significant extension to tracer life in controlled release tracer applications as well as improved dispersibility within fracking fluid. Newer synthesis mechanisms like microencapsulation have been developed to linearize inflow tracer release profiles that has led to a substantial increase in tracer lifetime. As the research and development progressed, newer tracers such as frac bead tracers were developed allowing long term fluid flowback monitoring in fracture stimulated wells.

In parallel, it is still an active field of investigation as to how tracers can be integrated with common downhole completion and topside equipment of a well to accurately detect early water breakthrough.

The paper discusses the advances in these target areas where chemistry is constantly being upgraded to suit end user needs. Novel applications and ‘out-of-the-box’ uses have been developed in the last couple of years where inflow tracers have found a modified use within the gas lift system in a well and integrated with the top-side flow arm of the well, eradicating the need for individual sampling of wells and detection of water breakthrough at an early onset, thus aiding timely decision making and improved recovery from the well. Real time analysis of tracers have attracted attention for quite some time now. The paper also discusses the latest development in this area and the challenges associated with real field applications.

While advancements in versatility of the tracer molecules have been published prior in literature, to the best of the authors’ knowledge, no work has been published to date that discusses the latest advances in unconventional uses of the tracer molecules aiding EOR and IOR processes.
Key Success Factor for High Power Laser Deployment: Strategy and Execution
Authors: Batarseh Sameeh , San Roman Alerigi Damian Pablo , Al Harith Abdullah
Published: March 2023

This paper presents the strategy and execution that led to the industry's first successful deployment of a high-power laser in the field. The development encompassed various aspects: administration, technical, lab-to-field transformation, and intensive research.

One of the primary success factors was identifying potential technologies and forecasting their evolution. High-power lasers were selected for the upstream applications because of their capabilities and successful use in almost every industry, ranging from medical to the military; it attracted the industry due to its unique features, such as precision, reliability, control, and accuracy. High-power lasers at the early stage (generation) were not applicable for downhole applications due to their relatively lower power levels. However, it has been utilized widely in several applications, such as sensing, measurements, and others. The objective of this program is to utilize the new generations of higher-power lasers in several upstream applications. The program is strategically designed to reduce the risk and increase success. In the initial stage, the work focused on the feasibility and characterization of intervening physics. The goal was to answer fundamental technical questions, such as "can lasers penetrate all types of rocks? What are the limitations? What is the effect of the laser on rocks?" The research spanned the last two decades, culminating in the development of the first field prototype of a high-power laser system.

The work proved that near-infrared multi-kilowatt lasers (hereon high-power lasers or HPL) could perforate and process any rock type at different conditions, including in-situ testing and liquid environments. The experimental plan was designed systematically and divided into phases, starting from fundamentals to advance. Prototype tools were designed, tested, and upscale for field deployment. All applications can be performed with the same HPL source -only the optical head needs to be changed.

High-power laser technology is an alternative to conventional methods of subsurface energy extraction, such as perforation, descaling, and drilling. It is cost-effective, compact, versatile, waterless, energy-efficient, and environmentally friendly, thus enabling sustainable field operations.
Hydrolysis-Promoted Polymerization of Furfuryl Alcohol: Selective Method for Mitigating Excess Water Production in Oil Wells
Authors: Cairns Amy J. , Saini Rajesh K. , Chang Fakuen F.
Published: March 2023

Water production during hydrocarbon extraction is a major problem for the upstream oil and gas industry. The challenge posed for operators is the increase in operational costs pertaining to separation, treatment, and disposal processes, amongst others. A wide assortment of scenarios can lead to unwanted water production from wells in hydrocarbon producing zones such as casing leaks, cusping, water breakthrough due to the presence of natural fractures or high permeability streaks, etc.

Methods of treatment are not a one-size-fits-all approach but range from being simple to more complex. To best mitigate the problem, particularly in the long-term, it is necessary to perform a thorough evaluation to understand the location and cause of the water production. Key existing solutions use mechanical devices, chemical methods, or combinations thereof to form a semi-to-impermeable barrier to prevent the flow of water from reaching the wellbore. While potentially very effective, the longevity of such methods is hindered by lack of efficiency, selectivity, stability, high cost and placement risks in relation to the completion type.

Here, we report on the development, formulation, and performance evaluation of a robust thermoset resin system that is inherently selective for blocking water -bearing zones in oil producing formations. The strategy behind this approach is based on acid-catalyzed polymerization of furfuryl alcohol. Specifically, use of judiciously selected acid-generating precursors, namely ester-containing compounds that are hydrophobic in nature. Under suitable reaction conditions, hydrolysis takes place at the interfacial boundary thereby releasing acid and directing blockage specifically to the water zone via resin formation.

The resin system has been formulated for application in carbonate or sandstone reservoirs with temperatures up to 150 ˚C and set times up to 48 h. In this study, an overview of our down-selection process for ester selection guided by static bottle test results and regained permeability data obtained under reservoir conditions using a coreflood apparatus will be discussed.

This chemical method for mitigating excess water production in oil wells is configured to selectively plug the water producing zones without affecting the oil producing zone. Instead, it is proposed that suitable chemical placement can be achieved by bullheading the treatment into the formation thereby reducing operational complexity and cost.