bluuebunny/crossref_metadata_2025 huggingface dataset:
De-Risking Upper Cretaceous A Formation Production by Joining Multiple Technoologies in 3D Space
Authors: Cazeneuve Eduardo Adrian , Bouzida Yasmina , Smirnov Vladimir , Singh Maniesh , Ahmed Jahan Zeb , Singh Nepal , Celma Rafael , Shehab Sami Sheikh Alawi
Published: March 2023

Realistic geological characterization is crucial for the development of carbonate reservoirs specially to overcome some challenges related to Early Water Break Through (EWBT) like those observed in the Upper Cretaceous ‘A’ Formation. The complexity of the depositional, diagenetic, and structural history created unpredictable connected pathway with the aquifer. Therefore, having suitable conceptual geological models tied to well data helps to better anticipate their occurrence and extension to plan for suitable well placement, a completion design, and optimize the production.

The objective in this case study was to assess the Deep Shear Wave Imaging (DSWI) technology that can bridge the scales between well Borehole Image (BHI) and conventional Seismic to identify sub-Seismic features up to 100ft away from the well bore. A statistical evaluation of the BHI was used as a reference for this DSWI assessment. Then the result was compared with Seismic coherency to assess the value of the combined data.

This cross-discipline integration in 3D from different data measurements with a variety of scales by order of magnitude difference between them (Well and Seismic), has allowed to build a conceptual model of the near wellbore region up to 90ft and predict five significant fault zones that are susceptible of connecting with aquifer. Dynamic data will be used in the second phase of the project such as (liquid rate, water breakthrough and tracers) to analyze their contribution to the EWBT and refine/enhance the interpretation.

The way forward is to apply a similar workflow to other wells in the field, to gain a solid understanding of the sub-seismic architecture of the subsurface and hence timely optimize the setup of Inflow Control Device (ICD) design used to mitigate EWBT.
Application of Image Processing Techniques in Deep-Learning Workflow to Predict CO2 Storage in Highly Heterogeneous Naturally Fractured Reservoirs: A Discrete Fracture Network Approach
Authors: Tariq Zeeshan , Yan Bicheng , Sun Shuyu
Published: March 2023

Naturally fractured reservoirs (NFRs), such as fractured carbonate reservoirs, are commonly located worldwide and have the potential to be good sources of long-term storage of carbon dioxide (CO2). The numerical reservoir simulation models are an excellent source for evaluating the likelihood and comprehending the physics underlying behind the interaction of CO2 and brine in subsurface formations. For various reasons, including the rock's highly fractured and heterogeneous nature, the rapid spread of the CO2 plume in the fractured network, and the high capillary contrast between matrix and fractures, simulating fluid flow behavior in NFR reservoirs during CO2 injection is computationally expensive and cumbersome. This paper presents a deep-learning approach to capture the spatial and temporal dynamics of CO2 saturation plumes during the injection and monitoring periods of Geological Carbon Sequestration (GCS) sequestration in NFRs. To achieve our purpose, we have first built a base case physics-based numerical simulation model to simulate the process of CO2 injection in naturally fractured deep saline aquifers. A standalone package was coded to couple the discrete fracture network in a fully compositional numerical simulation model. Then the base case reservoir model was sampled using the Latin-Hypercube approach to account for a wide range of petrophysical, geological, reservoir, and decision parameters. These samples generated a massive physics-informed database of around 900 cases that provides a sufficient training dataset for the DL model. The performance of the DL model was improved by applying multiple filters, including the Median, Sato, Hessian, Sobel, and Meijering filters. The average absolute percentage error (AAPE), root mean square error (RMSE), Structural similarity index metric (SSIM), peak signal-to-noise ratio (PSNR), and coefficient of determination (R2) were used as error metrics to examine the performance of the surrogate DL models. The developed workflow showed superior performance by giving AAPE less than 5% and R2 more than 0.94 between ground truth and predicted values. The proposed DL-based surrogate model can be used as a quick assessment tool to evaluate the long-term feasibility of CO2 movement in a fracture carbonate medium.
Energy Transition in the Oil & Gas Industry – Emerging Technology Trends in the Upstream Sector
Authors: Buranaj Hoxha Bez , Nair Aravind
Published: March 2023

The energy transition is a popular concept, fettered by technology hype, political agendas, and financial influences that are inherently attached to the term ‘energy transition’. There are a lot of misconceptions and intricacies behind the strategies operators are undertaking in this energy paradigm shift. Therefore, clarity is needed on what is driving this paradigm shift: technology, policy, and cultural change.

The scope of this paper focuses on defining the different strategies operators are adopting in their operations that align with transforming business models in the energy transition pathway. Predominantly segmented on various emerging technologies being implemented during operations and processes in upstream sector. Technologies that were barely considered before are now being deployed. Furthermore, explanations and considerations will be offered on emerging technology trends implemented in field operations, from subsurface drilling to completion.

Lastly, the information and data presented herein are based on industry market intelligence supported by personal case studies and primary and secondary market research.
Anisotropic Poroelastodynamics Solution and Elastic Moduli Dispersion of a Naturally Fractured Rock
Authors: Liu Chao
Published: March 2023

In this work, the theory of anisotropic dual-porosity dual-permeability poroelastodynamics is used to simulate the responses of pore pressure, displacement, and stress of a fluid-saturated transversely isotropic naturally fractured cylindrical rock sample. The sample is subjected to a harmonic loading with a constant displacement amplitude at one end. These solutions are then use d to calculate the elastic moduli dispersion of the rock sample. A transversely isotropic water-saturated rock sample is selected as an example to demonstrate the simulation and the mechanisms of the dispersion due to the coupled motions of the rock matrix and fluids in pore spaces and fractures. The effects of material anisotropy on the poromechanical responses and the elastic modulid dispersion of the rock sample are presented. We also show excellent matches between the simulation and laboratory measurements of the dynamic Young's moduli of two shale, one clay, and three sedimentary rock samples.
A Method for EUR Forecasting in Unconventional Reservoirs Using Early Flowback Data
Authors: Mahmoud Ihab , Alsulaiman Nouf
Published: March 2023

Evaluating EUR and production forecasting in multi-frac horizontal wells completed in unconventional shale reservoirs during early, exploration and appraisal stages is very challenging. With the absence of suitable production facilities to handle produced fluids, production data are limited to short flow backs and extended production for some key wells to early production facility (EPF).

This method uses the flow capacity as an intrinsic parameter that captures and reflects the major drainage mechanism and recovery characteristics of the well within the unconventional reservoir. Thus, the flow capacity may serve as a reference parameter that can be estimated from early-time data. This parameter may have the ability to reflect the future production behavior of the well in terms of cumulative production through proportional comparison of flow capacity to EUR.

To show applicability of the workflow, it was applied to an existing unconventional project and showed consistent results. The workflow incorporates RTA analysis for several wells to create a single correlation that describes the relationship between Ac√k and EUR. Plotting gas flow capacity (Ac√k), estimated during the early 3-4 weeks of flowback, versus the estimated EUR from modeling techniques showed a strong correlation.

The proposed workflow is designed to estimate EUR for wells completed in unconventional reservoirs during the early phases of development, where there is no production facility to handle produced hydrocarbons and flow back period is limited to cleanup only. The advantages of the proposed workflow over the currently available methods are: (1) Incorporating several wells analyses to create a single correlation that describes the relationship between Ac√k and EUR (2) The ability to evaluate EUR from as-early-as 3-4 weeks of flowback data. The early evaluation of these wells will expedite critical completion and development decisions which will impact project economics.
Characterizing Movable and Non-Movable Zones in a Mature Carbonate Reservoir: A Novel Workflow Using Resistivity Logs
Authors: Al-Otaibi Saud , Aldajani Saud , Al-Sayyar Talal , Al-Marri Salem
Published: March 2023

Optimizing reservoir recovery depends on an in-depth understanding of natural geological complexity to predict reservoir behavior. Understanding the difference between producible oil and non-movable oil zones is important, which will aid in the refinement of the design of future wells.

During the mature life cycle of the Maastrichtian carbonate reservoir, it was observed that some wells would not perform optimally, while others would experience a significant drop in production. By analyzing petrophysical and production data, the reservoir was found to contain hydrocarbons consisting primarily of heavy oil and stringers of light oil. Based on reservoir characterization and after assessing the production profile to understand the hydrocarbon behavior, this study was performed to identify and distinguish movable oil zones from non-movable oil zones.

Conventionally, expensive intervention methods, such as running modular dynamics formation tester (MDT), nuclear magnetic resonance (NMR) logs, and production logging tools (PLT), are used to determine the oil viscosity (API) and identify contribution zones from the entire hydrocarbon interval. However, using these methods results in increased operational costs and reduced production.

This study proposes an alternative approach using resistivity logs to identify and distinguish between movable and non-movable hydrocarbon zones to improve reservoir management. The concept behind this method depends on the resistivity logs validated using MDT and PLT data. A shallow resistivity reading higher than a deep resistivity reading indicates that hydrocarbons were not flushed (unmoved) by invasion. Thus, the zone contains unproducible hydrocarbon reserves. The resistivity cut-off value was estimated based on the PLT and MDT data to identify movable oil intervals.

In all the wells analyzed, there was a good correlation among the calculated zone thickness, core data, sampling data, and mud logs. Dielectric logs were run in a couple of key wells, which enabled the Sxo estimation independent of resistivity. Additionally, the Sxo obtained supports the fluid interpretation. Productive zones were accurately identified for each well, and recompletions were made to produce from these bypassed opportunities.

The proposed method is robust with respect to environmental corrections, not contingent on MDT, NMR, and PLT knowledge, and can be carried out without halting production.
Novel Carbon Dioxide (CO2) Foamed Fracturing Fluid, an Innovative Technology to Minimize Carbon Footprint
Authors: Samuel Mathew M. , Al-Jalal Ziad , Nurlybayev Nurlan , Farouk Mohammad , Xiao Zhijun , Kang Kang Cheng , Huanming Li
Published: March 2023

Decarbonization is one of the greatest challenges that our nation is facing now and can be achieved by lowering the carbon footprint. This is believed to address the climate change (Miralles-Quirós et al.) and this task necessitates the development of technologies for energy production and storage, carbon capture and utilization in a very wider scale (UN FCCC, 2015). The present study is an attempt to utilize carbon dioxide in oilfield operation that does not require any equipment or infra structure other than what already present in a fracturing field location.

Hydraulic and acid fracturing treatments based on foamed fluid reduce the overall amount of liquid pumped, provide better fluid-loss control and diversion, and aid in post-treatment flowback. Foam fracturing causes less damage to formation, fracture face and proppant pack, improving the productivity of oil and gas well. Among nitrogen and carbon dioxide (CO2) gases used to create foams, use of CO2 is preferred over nitrogen, though it is operationally complex. Positive impact of low carbon is widely accepted and can be achieved either by producing less carbon dioxide, carbon capture and sequestration, or by its reuse. This paper will describe a novel and highly stable foam fracturing fluid based on a new Spiral Gel (S-Gel 38) polymer-foamer system that is developed to reuse the produced carbon dioxide and thus to lower carbon footprint.
An Integrated Ensemble Based Prediction Approach to Quantify and Propagate Uncertainties of Naturally Fractured Carbonate Reservoirs
Authors: Abd-Allah Mohammed , Abdelrahman Ahmed
Published: March 2023

Naturally fractured reservoirs are holding most of the hydrocarbon proven reserves worldwide. Field development planning and optimization of fractured reservoirs face significant challenges due to fracture system complexity, high reservoir heterogeneity and multiple recovery mechanisms. Fractured systems generally have multiple sets of fractures in different orientations, multiple apertures ranging from tiny fissures to large fracture conduits resulting in complicated fluid flow.

Reservoir modeling plays a key role in field optimization by examining reservoir recovery under various scenarios. Traditionally, modeling fractured reservoirs is a deterministic process using a single or few reservoirs model (high, mid, and low cases) without proper integration of seismic-to-simulation reservoir model uncertainties. The full span of possible reservoir models and prediction uncertainty isn't captured nor propagated to economics.

This paper presents an integrated forward modeling workflow using a Synthetic 3D model data mimicking a real North Sea field, where static and dynamic models are tightly connected to integrate the impact of uncertainties at different modeling stages (horizon uncertainties, fault uncertainties, petrophysical uncertainties, discrete fracture network (DFN) uncertainties to dynamic simulation).
Successful Testing and Sampling the Desired Formation Fluids Despite the Challenging Environment in the Middle East
Authors: Espinoza Irina Baca , Perdigon Rony , Osunluk Halil , Mushir Khan Kashif
Published: March 2023

Most of the time a brownfield's formation producibility is no surprise to petrophysicists and reservoir engineers, however, the downhole conditions change continuously in the oil and gas production and injection. Therefore, it is critical to acquire high-quality representative testing and sampling data in real-time despite formation uncertainties and operation constraints.

There are several challenges when acquiring the wireline formation testing (WFT) and sampling services in Middle East. The downhole real time fluid properties must be representative of reservoir conditions and provide fluid fractions, water salinity, contamination, etc. At the same time, there is a big constraint on the operational time limit per station due to the substantial risk of getting stuck. In complex lithologies, it is critical to understand the fluid's connectivity between layers and rock compressive strengths as the expectations may not match reality. To meet the abovementioned challenges the WFT technologies must be equipped operationally and provide a valid instantaneous interpretation.

Current research covered cases across several countries in the Middle East. In low-mobility formation the challenge was on operational ability to continuously pump-out for extended hours. The record-breaking results were achieved with 36 hours of pumping-out, with bubble point as close as 50 psi below formation pressure. Some advanced features were implemented including FT pre-job modeling and real-time support vertical interference tests, which helped to complete the injector well as planned. Many challenges comes in differentiation between formation and filtrate water in real-time. It was solved using the only resistivity sensors available in current WFT setup. For deep tight gas reservoirs, the sampling in tight environment were an issue, nevertheless, getting a single sweet spot allowed to collect representative gas samples. Dealing with retrograde condensate field might be tricky when the condensate precipitation and gas appearance are not known. In presented cases the two scenarios shows the appearance of gas across the zone and appearance of condensate. The results were compared to production logging (PLT) to clarify the unusual multi-phase changes in phase behavior.
Innovative Workflow for Wellbore Stability Evaluation Using Logging-While-Drilling Technologies
Authors: Fouda Mohamed , Taher Ahmed , Al-Hassan Mohammed
Published: March 2023

Logging-while-drilling (LWD) technologies have long been used for real-time formation evaluation and geosteering. Several optimization techniques for drilling and completions have been developed, based on data acquired from emerging and existing LWD technologies. In this paper, methods and techniques are presented where LWD measurements were utilized for the purpose of safely planning, drilling, and completing vertical and horizontal boreholes.

Optimizing drilling and completions can be achieved by continuously monitoring for signs of deteriorating borehole conditions in data coming from different LWD sensors like density, resistivity, or ultrasonic imagers. In addition to resistivity tools known to provide shallow and deep readings, density tools provide azimuthal borehole images from two detectors of different source-detector spacings, allowing their data to have different depths of investigation (DOI). Comparison between the responses of sensors having different DOI over multiple logging passes can be used to assess wellbore deterioration over time. Emerging tools like ultrasonic LWD imagers provide high-resolution, azimuthal hole-size measurements allowing advanced evaluation of wellbore conditions.

Analysis of LWD data showed the potential to identify, mitigate or eliminate existing and potential wellbore stability risks. Integrating multiple sensors of different DOI in the logging suite, and comparing their individual responses, gives more insight into the borehole conditions than analysis of single-sensor data alone.

Customized workflows were established where available data from LWD was integrated with surface-data-logging (SDL) data to provide full analysis of wellbore conditions in real time. Time-lapse analysis using data acquired while tripping out of the hole revealed deterioration that was not observed in the first logging passes while drilling. Interventions were made to mitigate wellbore instability and lessons have been captured to prevent hole deterioration in subsequent wells drilled in the area.

Workflows have been developed to utilize existing and emerging LWD technologies for wellbore stability monitoring. Procedures have been established to mitigate borehole deterioration, thereby optimizing operations for drilling and completions.
Achieving Well Cleanup and Zero Routine Flaring Utilizing Existing Flowline and Ecxtended RTP
Authors: Aldughaither Abdulmajeed , Marri Saleh , Albuali Muhammed
Published: March 2023

As part of Zero Routine Flaring initiatives, advanced steps have been taken to align with goals of minimizing carbon footprint. Therefore, several important technologies have been widely exploited for usage in oil and water wells. Additionally, restrictive regulations were implemented including the prohibition of oil and water wells flaring. This paper outlines the combination of technology and existing facilities to ensure zero flaring while cleaning a well.

The well is a disposal well for a hydrocarbon facility. During normal surveillance, the well was identified with losing its injection capability and having a high pressure. Therefore, the well required cleanup and acid stimulation to restore its injection capability. However, the well can't flow to the hydrocarbon facility due to one-way valves on its flowline in addition to the inability to flare. Accordingly, a procedure was developed to flow the well to the facility through a temporary installed 6.5km HT Reinforced Thermoplastic Pipe (RTP) in an uneven landscape to connect the well to the nearest existing producer carbon steel flowline.

The developed procedure enabled the successful achievement of maintaining zero routine flaring. Also, the cleanup operation was safely and successfully conducted by flowing the well continuously for 48 hours through the installed RTP line. The successful cleanup helped to conduct an acid stimulation using a 2-3/8″ HPCT to restore its injectivity and aid the facility to dispose its processed water in the well to meet its production target. Following the acid stimulation, nitrogen purging of the RTP line was required to ensure the presence of no liquids in the line to avoid environmental pollution when disconnecting the line

This paper highlights a comprehensive procedure to overcome a challenging case of a well located in a remote area and uneven landscape in which a group of solutions were combined to restore a well's injectivity while maintaining zero routine flaring.
Modeling of Multi-Component and Thermal Flow for Geologic Carbon Sequestration Using Operator-Based Linearization Approach
Authors: Kumar Ajitabh
Published: March 2023

Multi-component and thermal flow modeling has been applied in oil and gas industry for last few decades. But its application is challenging due to growing size of simulation models and need to handle multi-physics. In this study, operator based linearization (OBL) approach is used to model multi-component and thermal flow with application to geologic carbon sequestration.

Geologic carbon sequestration studies require different approach as compared to conventional oilfield as the size of aquifer and time-scale of simulation are relatively large. Also, sparse data availability necessitates systematic simulation study with hundreds, if not thousands, of simulation runs to capture underlying uncertainty. With this in mind, operator based linearization is used to model nonlinear flow in carbon-dioxide storage in subsurface. Compute expensive fluid model is handled using operator table, and state values are interpolated using multi-linear interpolation.

Approach is applied to carbon-dioxide injection modeling in first multi-component, iso-thermal setting and then in multi-component, thermal setting. Implementation of OBL formulation in the open-source GEOSX simulation tool is used in this study. A static operator table is included at the start of simulation in which state-dependent operators are parameterized using mesh in parameter space. OBL approach accelerates time required for simulation by replacing compute-expensive calculations with multi-linear interpolation, while also introducing some approximation errors. This approach would be applicable in simulation workflow where hundreds of simulation runs are required to make decision.
Effective Method for Decontamination of Compromised Slug Catcher: Case Study
Authors: Braganza Giselle , Gomes Joel
Published: March 2023

This paper describes a vapour phase method for cleaning and decontamination of a slug catcher in a gas processing plant. Corrosion and heavy metal losses required the slug catchers to be replaced. Safe decommissioning demanded the elimination of H2S, LEL and pyrophoric iron. Compromised integrity made traditional cleaning methods like circulation or pressure jetting unfeasible. The proposed method significantly reduced decontamination times and the associated effluent.

The vapour phase method using degassing chemicals entrained in steam lowered H2S and LEL levels to substantially zero and also neutralized the pyrophoric material. The entire cleaning process was conducted with a temporary H2S scrubber due to unavailability of the process flare. This method did not require the system to be liquid filled or subject to high jetting pressure, making it possible to limit the treatment pressure to below 2 barg, thus minimizing the stress on the structural integrity of the slug catcher. In addition, the slug catcher weak zones were fortified externally in preparation for decontamination.

This technique of using steam as a medium to distribute and apply the degassing chemicals throughout the slug catcher has proven to overcome the limitations of conventional cleaning methods. It further provided a viable solution to reducing the time and resources required to achieve substantially zero H2S, LEL and pyrophoric content by half.

With traditional cleaning methods, the effluent generated would be substantial, necessitating additional logistical support for transporting the waste from the offshore location. Decontamination in a steam saturated vapour phase reduced the amount of effluent generated significantly, to only one third in comparison. This resulted in a solution that was more economical and environmentally friendly. Effective decontamination eliminated the risk associated with the presence of hydrogen sulfide (H2S) gas and pyrophoric materials, ensuring the slug catcher was decommissioned safely and successfully.

For heavily compromised systems and for locations with water supply, waste management or schedule constraints, the vapour phase decontamination process has distinct advantages over conventional methods.

The resultant savings in time and resources makes this an attractive option for mainstream oil and gas processing facilities as well.
Enhancing CO2-Foam Stability and Rheology Using Surfactants Mixture
Authors: AlYousef Zuhair , AlMajid Muhammad , Alabdulwahab Amin , Swaie Othman
Published: March 2023

Generating in-situ foam is regarded as one of the most promising techniques to overcome gas mobility challenges and, accordingly, improve sweep and sequestration efficiency in CO2 injection processes. Foam generation and stabilization at harsh reservoir conditions as well as surfactant-rock interactions are the major limiting factors that can impair the efficiency of foam flood. Surfactants mixtures offer the solutions necessary for the generation and stabilization of foams at harsh reservoir conditions.

In this study, mixtures of anionic and amphoteric surfactants have been evaluated in comparison to using each surfactant individually to determine the overall effect on producing stable foams. Using bottle foam tests, dynamic foam analyzer, and foam rheology apparatus, the foam stabilization factors were analyzed and quantified. The bulk foams for each surfactant and the mixture of the two surfactants at different mixing ratio were analyzed by measuring the foam-life over time, the foam bubble sizes, and the foam rheological properties at high pressure, high temperature (HPHT) and using high salinity water.

The experimental results clearly demonstrated that the use of surfactant mixtures improved the stability of produced foam. The results revealed that the mixing ratio of each surfactant significantly impacts the foam stabilization. The surfactant mixture solutions produced more stable foams as evidenced by a longer foam-life. The foam-life increased by almost 1.5-2 times depending on the mixing ratio. The results also revealed that there are ranges of concentrations at which the most stable foams can be produced. The foam rheology results showed that the produced foams using the surfactant mixtures are of higher apparent viscosity when compared to those obtained with the anionic surfactant. The addition of the amphoteric surfactant to the anionic surfactant solution enhanced the foam stability, and accordingly, the foam rheological properties. The measured foam apparent viscosity increased as the concentration of the amphoteric surfactant increased. Longer foam-life and greater apparent viscosity are indicative of better, stronger and more stable foams.
Towards Online Natural Gas Composition Analysis by Low-Field NMR Spectroscopy
Authors: Mohnke Oliver , Thern Holger , Ortiz Sergio , Swiatek Anna , Ohligschläger Andreas , Duchowny Anton , Dupuy Pablo Matias , Widerøe Hege Christin , Leknes Øyvind , Küppers Markus , Adams Alina
Published: March 2023

The most common NMR methods in the oil and gas industry are NMR relaxometry and diffusometry. Relaxation times T1 and T2 as well as diffusivity D are determined for characterizing fluids and their surrounding pores in logging applications or laboratory analyses. NMR spectroscopy is rarely used for petrophysical investigations but primarily in medical, food, and material applications. In a joint operator-academia-service company project, we explore opportunities for gas component quantification by low-field NMR spectroscopy with the prospect of rig-site, production-plant, and sea-floor deployment. Using an affordable benchtop device in a production-like environment, we gained a fundamental understanding for a commercially viable application of low-field NMR spectroscopy and translated this knowledge into a practical workflow for online natural gas composition analysis.

We measured typical natural gas components (all isomers from methane to n-hexane) with a portable desktop NMR spectrometer working at a proton resonance frequency of 60 MHz A hardware setup was manufactured for mimicking a gas production environment up to 200 bar. A database was populated by NMR signatures of pure gas components, derived from measurements on pure components and binary mixtures. Additional efforts were dedicated to understanding and quantifying systematic effects on the hydrocarbon NMR spectra connected to sample composition and pressure. Pre- and post-processing data procedures were developed and applied for substantially increasing robustness of the method and further improving the gas composition analyses results. Using an indirect hard modeling (IHM) analysis, the constituting pure components in binary, ternary, and more complex gas mixtures were identified and quantified. IHM automatically accounts for small variations and uncertainties in the NMR spectra. The results from the NMR spectrum analysis are in very good agreement with vendor certificates of gas composition obtained from gravimetrics and gas chromatography.
Wellhead Protective Measures During Well Stimulation Operations; Current Limitations and New Horizons
Authors: Mukhlifi Mohammed , Al-Aamer Mansour , Wirawan Pandu , Muqri Mohammed , Saeed Mohammad
Published: March 2023

Wellhead and production trees are the primary safety barriers on any gas, oil and water wells. Such wells may require flowing corrosive or abrasive fluids through the permanent wellhead components as part of well stimulation to restore well productivity. This paper describes the limitations of the available methods to protect wellhead equipment during acid stimulation jobs and proposes a new solution that will provide the required protection and field operation optimization.

Current wellhead protection solutions during well stimulation activities fall under two methods; utilizing sacrificial equipment during well stimulation or utilizing tree savers on permanent wellhead equipment. Both approaches have their drawbacks. The former involves additional operational cost to install and remove the sacrificial equipment. Furthermore, well securement involves killing the well which will diminish the effectiveness of the stimulation job. The latter utilizes proprietary technology that is limited by well completion size and does not offer protection for all production tree sizes.

The proposed solution involves setting an isolation sleeve across the permanent wellhead equipment. A sacrificial set-up is installed on top of the permanent production tree to facilitate isolation sleeve installation, well stimulation activities and maintain well control requirements. The sleeve will be retrieved and the sacrificial set-up removed once the stimulation operations are concluded.

This technology bypasses the limitations of the available methods. It provides full protection from the production tree to the tubing hanger from abrasive fluids pumped and pressure during well stimulation jobs. Furthermore, it does not require killing the well to remove the sacrificial set-up resulting in optimizing rig operations and maximizing the benefit of well stimulations. Finally, it has no limitations to production tree size unlike the existing solutions.

The methodology presented in this paper provides a novel solution to ensure complete protection to the wellhead equipment during well stimulation, minimize operation cost and bypass the current limitations from the available solutions in the market.
New Insights for the Use of Lactic Acid in Carbonate Acidizing
Authors: Alhamad Luai , Caliskan Sinan , Alfakher Basil , Ibrahim Hussain
Published: March 2023

Utilizing HCl on deep high-temperature formations is associated with corrosion and reactivity concerns. Organic acids are a common choice for conducting matrix acidizing on carbonate formations where the use of HCl is limited or unfavorable. An organic acid can stimulate as a standalone formulation, mixed with another type of organic acid, or mixed with HCl. One commonly used organic acid is Lactic acid, which has a dissociation constant similar to formic acid, which is approximately 10 times larger than acetic acid. The objective of this work is to show experimental results conducted using lactic acid for matrix acidizing.

Solubility tests using a HPHT autoclave were done to evaluate acid-carbonate reaction and produced by-product salts. Coreflood tests were performed on Indiana limestone core plugs to mimic a matrix acidizing procedure and to investigate the amount of pore volumes required to breakthrough. These tests were monitored by using inductively coupled plasma (ICP), X-ray diffraction (XRD), and computed tomography (CT) scans to measure different ion concentrations in solution, to identify precipitated solids, and to evaluate dissolution patterns generated in the coreflood test, respectively.

The reaction of lactic acid with carbonate rocks was associated with production of calcium lactate which found to be soluble above 150°F. Lactate-based precipitation was avoided by incorporating gluconic acid along with lactic acid. In addition, lactate-based precipitation was avoided by mixing low concentration lactic acid with HCl. Adding HCl to lactic acid solution allowed for the reduction of lactic acid concentration to a precipitation-free level where lactate ions would be at a minimum. Coreflood results established more understanding of lactic acid utilization in matrix acidizing in terms of minimum pore volumes to breakthrough and generated wormholes. The results highlighted the correlation between acid-core reactivity, injection rate, and dissolution pattern. Coreflood tests showed that the lactic acid blends at optimum injection rate penetrated tested core plugs with minimal acid pore volume without any face dissolution or salt precipitation on the plug faces. Coreflood tests showed that the lactic/gluconic acid blend can stimulate carbonate cores and generate an optimum wormhole. A lactic/HCl blend was more reactive than a formic/HCl or lactic/gluconic acid blends as more pore volumes were needed to breakthrough Indiana core plugs. Thereby, a higher injection rate is required to obtain an optimum pore volume to breakthrough despite the high reactivity.

The detailed experimental work shown in this study shows major advantages that can be achieved by using different lactic acid-based blends. Among these advantages are favorable dissolution pattern due to lactic acid retardation, and less corrosion rates that can reduce allocated costs for maintenance and replacements.
Rotating Equipment Switchover Optimization to Enhance Equipment Reliability and Minimize Emissions
Authors: Gohel Kinnjalkumar
Published: March 2023

The association of rotating equipment switchover strategy with machinery health and reliability is discussed. The paper includes the design considerations for spare equipment in processing facilities, need for a switchover strategy, factors affecting the equipment switchover and the benefits of optimizing the switchover strategy in terms of equipment reliability and HSE.
New Formulation for High Temperature Acidizing Treatment Using Sustainably Sourced Additives
Authors: Li Jiang , Suzanne Stewart , Jonathan Abbott
Published: March 2023

Calcite reservoir represents a significant portion of hydrocarbon resources in subterranean formations. Most mineral acid based stimulation treatments to carbonate and sandstone reservoirs under high temperature encounter a fundamental problem, i.e., the etching rates are too fast and the treatment fluid is fully spent before it has the opportunity to be transported deeper into the formation, resulting in ineffective matrix treatment. The materials and compositions described herein are able to modulate the critical etching rate so that it can penetrate deep into the formation, generating a more extensive wormholing network required for high production yield.

This paper intends to report a new formulation that is capable of modulating the reaction rates between mineral acids and carbonaceous materials that are associated with important subterranean treatments including matrix acidizing, acid fracturing and filter cake dissolution. The formulation is composed of two environmentally friendly and sustainable materials; one polymeric with direct effect on acid reaction rate modulation by controlling the mass transfer rate of acidic proton at a given temperature in a tunable manner, and the other, micro fibrous bundles functioning to keep the reaction products from aggregating.

A full range of laboratory based qualification tests will be presented to demonstrate the principles of the functional additives in the new formulation. At ambient temperature, it was demonstrated that the reaction rates with calcium carbonate powder and Indiana Limestone can be modulated by using different dosages of the formulation. In addition, the typical acid fume in the headspace is effectively suppressed in the presence of the formulation. Furthermore, the formulation is compatible with commonly used corrosion inhibitor over extended time, and the corrosion inhibition performance using common metallurgies in the presence of an appropriate dosage of corrosion inhibitor between 250°F and 320°F over 6-12 hours duration met the oilfield performance requirement. The proof of concept coreflooding tests using Indiana Limestone and Bonne Terre Dolomite cores have identified domains of injection rates that exhibiting high efficacy of core penetration with a minimum of acidizing agent required. In addition, corrosion inhibition tests at temperatures ranging from 250°F to 320°F, duration from 6 to 12 hours, and acid concentrations at 15% and 20% HCl equivalent.

The new acid formulation is anticipated to bring major advantages to acid stimulation jobs including: (a) deployablility to higher temperature domains that are otherwise beyond the reach of raw mineral acids; (b) deeper wormholes to enhanced well productivity; and (c) cost-effectiveness because of its remarkable breakthrough efficiency it exerts in carbonate reservoir compared to larger volumes of conventional acidizing systems that are needed for similar treatments.
Establishing Critical Gas Velocities for Liquid Loading in Deviated Gas Wells
Authors: Ejim Chidirim
Published: March 2023

Severe liquid loading in wells producing from some wet gas reservoirs, results in the well being unable to transport fluids to surface. In field applications, liquid loading is known to be more pronounced in deviated wells than in vertical wells. This study highlights a methodology to estimate the critical velocities for liquid loading in inclined gas wells. Knowledge and use of the technique is of importance to production engineers and stakeholders of a gas asset.

Test data from a 3-inch diameter line with inclination from vertical to near horizontal was obtained from open literature. For each deviation angle, and based on the test conditions, a correlation for liquid holdup in inclined wells was used to determine the void fraction at the region of interest. The corresponding maximum and average film thicknesses, as well as the interfacial friction factor were determined. The principle of momentum conservation for a deviated tubing was applied and the superficial critical gas velocities for liquid loading were estimated. These estimated velocities were compared to those obtained from the test data.

For the different superficial liquid velocities investigated, the estimated critical gas velocities increased with increasing deviation from vertical. The maximum critical velocity was reached when the deviation angle was about 40° to 50° from vertical. Beyond this point, the critical gas velocity decreased with increasing deviation angle from vertical up to the near-horizontal inclination. The results also showed that the gas critical velocity increased with increasing liquid superficial velocity. The overall trend of the critical velocity variation was similar to the trend in the actual test data obtained from open literature. The range of estimated critical gas velocities varied from about 9 m/s to about 35 m/s, with overall Root Mean Square Errors between 3.3 m/s and 6 m/s. In conclusion, results from this methodology was able to give a first-hand estimate of critical superficial velocities for inclined gas wells.

This work presents a methodology to estimate critical gas velocities for inclined gas wells. This knowledge is important for field engineers and asset managers in the planning and production phases of gas wells. The benefits include optimizing the gas completion hardware during design, and maximizing gas flow rates during production operation. Overall, this increases the economic bottom-line for the field operator.
First Successful 16 X 13.375-in. Casing-While-Drilling Operation in Kuwait Saves 27 Rig Days and Reduces Well Delivery Time
Authors: Muqeem Saleh , Al-Mulaifi Mohammed , Al-Assil Yasser , Sekhri Anish , Sulaiman Mai Yacoub , Shekhar Chandra , Abdelrahman Ibrahim , Abdulkareem Talal , Homi Jokhi Ayomarz , El Kady Mahmoud , Al Saad Naser , Al Muzaini Shahad , Mataqi Fatemah , Al Harbi Saad , Al Kanderi Naser , Herrera Delimar , Halma Jeremy , Ibrahim Sameh , James Biju
Published: March 2023

Drilling the 16-in. section in Minagish field wells in western Kuwait is among the most challenging well sections. Challenges include drilling through severe loss conditions, destabilized shale, and deteriorating hole conditions. These conditions can result in hole collapse or lost in hole of the drill string that requires sidetracking. The objective of project presented in this paper was to develop an engineered solution to drill through the difficult zones, lessen nonproductive time, and reduce the total well cost.

The solution proposed was to use casing-while-drilling technology with a drillable bit and drill through the fractured dolomitic limestone and sandstone formation while simultaneously setting casing. The drillable casing-while-drilling bit was specifically designed and engineered to conform to the formations in the field. The drillable casing-while-drilling bit is manufactured with a material that can be drilled out with either conventional roller cone or fixed cutter bits. A plastering process was used, which smears the cuttings generated by drilling against the borehole wall, seals the pores or fractures in the formation, and helps reduce fluid losses while maintaining well integrity.

The first successful 16 × 13.375-in. casing-while-drilling job in Minagish field reduced well delivery time for the operator and saved 27 rig days with substantial savings in the total well cost. The section was drilled successfully while encountering total mud losses through fractured dolomitic limestone and sandstone formations. Continued drilling managed to reduce losses with 30 to 50% returns and reached the target depth. Preventing the risk of losing the bottomhole assembly in the hole and alleviating the use of multiple cement plugs saved additional cost for loss-cure plugs to heal the loss-prone formations. After reaching the target depth, cementing, pressure testing of the casing, and drillout of the drillable casing-while-drilling bit using a rerun fixed cutter bit were performed successfully.

On an average, eight wells are drilled per year in this field. With the successful implementation and the savings obtained by using this casing-while-drilling technology in the first test well, there is the potential for substantial annual cost savings, help the operator deliver wells in less time, and eventually increase production by increasing the number of wells drilled per year.
Deployment of an Eccentric Borehole Conditioning Tool Yields Significant Drilling Efficiency Improvements
Authors: Bailey Michael James , Roberts Sion Llywelyn , Suleiman Ahmed , Ismail Ahmed
Published: March 2023

Wellbore conditioning has become prominent in recent years as operators strive to reduce flat time costs. This paper examines how an eccentric wellbore conditioning tool (WCT) improves drilling performance and reduces flat time in challenging sections. Torque and drag are common challenges in extended laterals, with micro-doglegs and ledges being major culprits, especially in hard carbonate formations. The performance of the WCT is benchmarked in terms of flat time components: trip speed, system torque, rate of penetration (ROP), casing operations, and on-bottom performance. The paper also scrutinizes the allowable parameter envelope for wells drilled with and without the WCT.

Laboratory testing was conducted to observe the behavior and effects of the eccentric WCT when confronted by the major wellbore conditioning challenges. Following these initial laboratory tests, a proprietary software program was created to determine the WCT's ideal bottom hole assembly (BHA) placement for field trials. Several field trials were conducted to validate the placement software's accuracy as well as the key benefits achieved by the WCT.

Development testing has proven that the WCT's capabilities reliably improve wellbore quality and reduce overall torque and drag. Also, a proprietary software program confirmed the most effective WCT placement. Overall, there was a net flat time reduction and a marked improvement in ROP—up to 35% when directly compared with and without the WCT. Reduced system torque and less stress on downhole tools enable a wider and, more importantly, higher drilling parameter window.

A new generation of eccentric WCTs has been introduced to solve a legacy drilling pain. Poor wellbore conditioning contributes to significant flat time costs for operators worldwide. A proven, effective solution has been long overdue; however, the WCT has shown to be a cost-effective tool, improving flat time and drilling performance. The benchmarking and exploration of drilling performance and reduced flat time provided by wellbore conditioning tools will allow others to exploit lessons learned and recapture drilling efficiency.