bluuebunny/crossref_metadata_2025_split huggingface dataset:
Test Methodology to Evaluate Cement Compatibility in Strategic Underground Gas Storage for Energy Transition
Authors: Cracolici Federico , Iorio Vanessa Silvia , Viareggio Alberto , Massara Elisabetta Previde , Volontè Giorgio , Bona Nicola Giovanni , Farina Daniele , Parrozza Fabio 
Published: February 2024

Abstract
The energy transition makes strategic Underground Gas Storage (UGS) a key technology to meet energy and emissions targets. Indeed, UGS can be useful not only for methane accumulation but also for other energy transition uses. No matter the type of storage utilized, the cement present in the well constitutes one of the main elements for the integrity of the entire process, as it must be able to ensure hydraulic insulation between the well and rock formation, especially in a reactive environment. This paper proposes experimental procedure to perform cement-fluid interaction studies. The cement to be used in the well must be compatible with the fluids to be stored i.e., carbon dioxide. Cement testing procedures related to standard placement and performance in the Oil & Gas (O&G) reservoir environment are detailed in the API Specification RP 10. Unfortunately, to date, there is no official standard procedures to verify the cement interactions with CO2 and other energy transition fluids. Although some results on the interaction between cement and reactive fluids are reported in the literature, these results cannot be easily compared with each other because the testing procedures are different, leading to specific constrain on the results.
To better understand this problem, a deep analysis of the commonly used testing procedure phases was performed. The different steps of cement sample preparation process significantly affect the results of the chemical-physical characterization of the sample itself, particularly the curing and aging stages in the presence of a reactive environment. Starting from this point, a complete experimental procedure was designed to standardize the entire testing process even in the case of different reactive fluids. This method combines the typical approach of the solid/fluid interaction studies with the cement testing of the O&G industry reference standards, integrating petrophysical and compositional analyses. A particular focus is also provided on the experimental set-up and the precautions necessary to make the testing procedure more reliable and reproducible. On top of that, the instrumentation suggested, and the characteristic testing times reported in this article make this experimental procedure applicable to a large variety of reactive fluids.
Consequently, this new standardized approach and the possibility to apply this method to different classes of fluids, makes it extremely versatile. Its usage constitutes a fundamental step to support specific cement formulation in UGS applications in the effort to ensure safe geological storage site utilization.
How the Innovative Tri-Axial Geophones Helped to Pinpoint the Source of Slow Building B and C Annulus Pressures
Authors: Mittal T. , Hussain M. Q. , Sandra D. N. , Al Shehhi M. S. , Singh M. , Khan P. N. Ahmed , Wright J. , Espinoza I. Baca 
Published: February 2024

Abstract
Well integrity assessment is a challenging task that is dependent on continuous technology enhancements, multiple data integration and careful interpretation. Not all challenges may demand immediate intervention and thus have a potential of long-term damage to both the well bore and the reservoir. One such challenge is fluid migration between two reservoirs – either behind the completion or through the damaged completion. In some cases, these fluids may find a way to surface and result in sustained annulus pressures (SAP) at the well head. In some extreme cases, these fluids may even bypass the wellbore and leak to surface.
Detecting the exact location of the source(s) of fluid entries and then tracing their path has always been a challenge. While fast building annulus leakage has been historically detected with traditional temperature surveys, a more informative and interpretative approach was taken in spectral noise logging technology. The challenge however remains for slow building leaks for which higher sensitivity sensors are required. Recently, an innovative Tri-Axial Geophones (TAG) based logging technology was introduced and mobilized across several fields to detect sources(s) of slow building Casing-Casing well head annulus pressure in addition to checking the hydraulic isolation of various reservoir layers and aquifers.
Evaluation of the Impact of Poor Logging Data on Mud Weight Prediction Through Development of Approximate UCS- Based Correlations for Fracture and Stability Pressure Gradients
Authors: Al Zeer S. , Hossain M. M. 
Published: February 2024

Abstract
This proposed paper aims to evaluate the impact of poor logging data on the prediction of accurate mud weight and to assess the impact of Uni-Axial Compressive Strength (UCS) for weak to moderate and moderate to strong formations with fracture and minimum mud/stability pressure gradients. Six approximate correlations are developed as a function of UCS to predict the fracture and stability pressure gradients for the stated range of formation.
This study employed MATLAB code for the analysis of logging data to identify instabilities in the offset well and estimate the rock's mechanical properties through numerical simulation. By incorporating data from nearby wells, the logging data were rectified, facilitating the recalculation of optimal mud weights using a geomechanical earth model. The case study focused on three UCS correlations suitable for weak to moderate and moderate to strong formations. Scatter plots of fracture and stability pressure gradients against UCS obtained from MATLAB simulation were generated and plotted, which were then combined to derive approximate correlations for each correlation through regression analysis for the prediction of minimum and maximum mud weights (referred to as stability and fracture pressure gradient) as functions of UCS within the considered formation range.
Inaccurate logging data, especially caused by hole enlargements or breakout for offset wells can lead to erroneous estimations of recommended mud weights for drilling plans which can pose serious technical, safety and financial risks in drilling operations. The proposed approach of corrections to the offset well's data has been observed to provide more reliable and safer recommended mud weights. About the UCS exanimation, the first correlation is a function of static Young’s modulus, the second is a function of P-velocity, and the third is a function of dynamic Young’s modulus and dynamic Poisson’s ratio. The first and second correlations have shown the representation of moderate to very strong formations which agrees with the formation of the case study while the third correlation has produced values of UCS which are not representative of the well as it demonstrates the behavior of weak formations. Regarding the relationship between UCS and mud weights, it was found that as UCS increases, the fracture pressure gradient increases while the stability pressure gradient decreases for all three correlations.
The workflow presented in this paper can improve the estimation of optimal mud weights for new wells before drilling, potentially reducing uncertainties and the associated risks of wellbore instability. The approximate correlations for various formation types, also detailed in this paper can potentially serve as approximate as well as valuable engineering tools that enhance the estimation of optimal mud weights without the need for in-situ stress data and other mechanical properties of the formation.
First Trial of On-Demand Activated Axial Agitation System on Abu Dhabi Offshore Operation
Authors: Wahyudi A , Biyanni H , Tamuli A , Agarwal C , Hermawirawan L , Nowfal M , Che R 
Published: February 2024

AbstractThe Axial Agitation System is an effective friction reduction solution on directional motor and rotary steerable system (RSS) bottomhole assemblies (BHA). Drilling performance in a high dynamic friction environment is often limited due to high fluctuations in the drillstring’s revolution per minute (RPM) and torque, often coupled with stick/slip. This drilling dysfunction diminishes the amount of energy spent on rock shearing. The weight on bit and torque from the surface are not efficiently transmitted to the bit. If left unchecked, the rate of penetration (ROP) will be suboptimal, and stick/slip may lead to mode-coupling of vibration (lateral, axial) and BHA whirl, increasing the risk of downhole tool failures and non-productive time (NPT).The Axial Agitation System has been successfully paired with RSS drilling BHAs in ADNOC Offshore fields in 13 different wells. The first three wells were qualitatively and quantitatively studied by Gohel et al.6. Performance analysis performed on each well against a comparable offset well consistently demonstrates considerable improvements in drilling performance. While efforts have been made to select offset wells with minimal differences (well trajectory, BHA and drillstring design, formations, etc.), there is still a variety of RSS applications where the Axial Agitation System’s benefits need to be fully quantified and objectively concluded.An On-demand Axial Agitation System that can be activated—when needed—allows for a more objective comparison since the bit, BHA, drillstring components, and dynamic environment remain constant. This paper analyzes the first trial results of this on-demand axial agitation system by benchmarking the drilling performance before and after activation in two wells offshore Abu Dhabi.The data were acquired from two wells with different directional profiles and BHAs to prove that the agitation effect was equally tangible in different applications. The analysis metrics include, but are not limited to, mathematically modeled algorithms during the planning stage, surface data acquisition systems, and downhole dynamics measurements.The results of the analysis quantitatively indicate an enhancement of the drilling dynamics by more efficient use of available energy for maintaining and improving the ROP. To further enhance system performance, lessons learned are identified and discussed in this paper.
Reducing the Sand Production from Semi-Consolidated Sandstone Formation by Mitigating the Silica Dissolution Factor During Water Breakthrough
Authors: Alameen Mohammed B. , Elraies Khaled A. , Mohyaldinn Mysara , Almansour Abdullah , Gmail Abdallah M. , Hagar Haithm 
Published: February 2024

Abstract
Sand production is a common problem associated with semi-consolidated sandstone due to the reaction between the injected water and sand formation. In this paper, the mechanism of quartz hydrolysis during water breakthrough is investigated to establish a relation between silica dissolution and rock strength as a function of water saturation. The study is conducted with static and dynamic experimental approaches to investigate the relationship between sand (quartz) and water, which is called quartz hydrolysis. The static approach used pure quartz fine and coarse particles at different water compositions and temperatures to find the reaction between silica and water. From static results, some cases have been selected to examine further through a dynamic approach (core flooding test) as a function of the water saturation. Then using a UV-Vis spectrophotometer to measure the silica concentration and dissolution rate. Whereas unconfined compressive strength is conducted to measure the change in sandstone core strength. The results regarding static conditions show that Distilled water has a higher impact on silica dissolution than the brine base. This is related to the saturation level of the solution reached. In terms of the pH effect, it has been found that the highest amount of silica dissolution is 12 pH then 3 pH. Meaning that at the highest pH 12 and lowest pH 3 the silica dissolution increases sharply. This is related to OH and H ions present in both high and low pH stimulating the reaction. Regarding salinity effect, it is seen that Sodium chloride and potassium chloride have the highest effect in silica dissolution. While for the core flooding test, the results show that an increase in water saturation leads to reduce the core strength as a function of an increase in silica dissolution, which weakens the grain particles and connections at grain-to-grain contact, ultimately reducing core strength and causing sand production. It is concluded that water quality has a significant impact on the amount of sand dissolved, and a correlation between silica dissolution and rock strength as a function of water saturation is established. This study’s findings are useful in designing optimum water quality for water injection and mitigating sand production issues in sandstone formations. Also, understanding the main reasons behind sand production for the semi-consolidated sandstone formation.
4D Geomechanics New Modelling Approach using Machine Learning Predictions for Giant North Kuwait Jurassic Field
Authors: Haas M. , Al-Hamad N. , Heiland J. , Hussein A. M. , Shekhar S. , Srivastava D. N. , Ramon J. , Abdel-Basset SLB M. , Al-Anzi Abdullah , Al-Ajmi Moudi 
Published: February 2024

ABSTRACT
Drilling new wells in the deep Jurassic formations of the North Kuwait fields has gained increased importance given its high gas production potential, which represents a strategic target for Kuwait's domestic gas independency. However, reaching these formations bears severe drilling risks and challenges caused by differentially depleted reservoir sections that lead to arbitrary stress distributions and high pore pressure zones. This study presents an integrated 4D geomechanical model that includes a machine learning model for the development of a drilling expert system. This allows to predict drilling events along any arbitrary well trajectory in the 3D field model by analysing the stress field based on the construction of a mechanical earth model. The model further assesses completion quality to hydraulically fracture the rock mass. The simulation covers a 34 million grid cell model and is based on high-resolution geological information, seismic inversion data, rock core laboratory data featuring uniaxial, triaxial, multiaxial geomechanical tests, scratch, creep behaviour and thick-wall cylinder tests as well as petrophysical logs from 54 deep Jurassic wells. Seismic acoustic impedance data served as a proxy for co-kriging the spatial distribution of geomechanical properties. In addition, fault and fracture models were incorporated at reservoir levels.
The drilling expert system allows for an easily applicable and efficient extraction of the required drilling parameters and rock properties along any arbitrary well trajectory to conclude on the probability of drilling events occurring. The derived wellbore stability analyses reduce the costly and time-consuming risks of wellbore collapses when passing through high pressure formations. The simulated 4D stress field yields a strike-slip stress regime with a minimum horizontal stress direction of 135°. Identified zones in the reservoir sections show high hydraulic fracture potential given by the under- and overlying stress barriers in the anhydrite formations for stress containment. The evaluation of critically stressed, natural fractures as well as faults lead to the conclusion of potential reactivation due to high pressure injections in the Najmah reservoir for hydraulic fracturing. The study successfully showcased the integration of domain geomechanics expertise and data science, to derive a 4D geomechanical earth model as input for training machine learning models to evaluate drilling integrity and hydraulic fracturing potential.
Research and Application of Rock Typing Using Deep Learning in Prediction of Carbonate Reservoirs of H Oilfield, Iraq
Authors: Xiaoli Gao , Lu Lv , Bo Wang , Yongli Wang , Ailing Wang , Junhui Hu 
Published: February 2024

Abstract

Objective/Scope
The loss of some important logging data especially lithology data in old oilfields and huge cost in manpower and material on drilling and coring have brought great difficulties to the development of oilfields. A new method using deep learning for rock typing is achieved to classify and count the limited logging data, establish appropriate pore-permeability (PP) relationship and reduce the risk of reservoir prediction, which provides a concise and effective way for carbonate rock prediction.

Methods, Procedures, Process
In allusion to the existed problems, the paper collects, ranks the correlation between rock types and conventional logging data, which establishes a neural network model based on deep learning, divides the carbonate reservoirs into 4 types, and estimates the pore-permeability relationship for each type. Finally, a pore-permeability cloud simulation was performed based on the geo-statistical inversion to set up a high-precision reservoir static model with perfect well-seismic tie. The reliable permeability property can be obtained which helps to accurately depict the spatial distribution of the reservoirs.

Results, Observations, Conclusions
The carbonate reservoir of M formation for H oilfield in the Middle East is of complex pore structure with strong heterogeneity and poor relationship of the pore-permeability (PP). The logs DT, GR, Density, Porosity as the input features of deep learning is optimized to train neural network models, which are applied to the sample for testing and verification. The sample tests from the optimized neural network model are as accurate as 86.8%. The results show that rock typing using deep learning and well logs found a non-linear mapping relationship which effectively and reasonably divided the carbonate reservoirs into 4 types. The geological statistics and stochastic simulation in geo-statistical inversion organically combine seismic information with rich reservoir parameters such as porosity, rock typing, permeability and so forth. The permeability inversion result is highly consistent with the drilling data, which means the reservoir distribution patterns and regularity have been greatly improved, the local characteristics of the reservoir have been described more detailed and accurate.

Novel/Additive Information
The paper establishes and optimizes a neural network model based on deep learning which extends the divided rock typing to the whole oilfield. The estimated permeability as new pore-permeability relationship was applied to the geo-statistical inversion, which achieved the high-resolution spatial prediction of reservoir parameters and satisfied the fine reservoir characterization. It reduces the huge cost on drilling and coring, also provides a concise and effective approach to improve the reservoir estimation and production efficiency.
Exploring CO2-H2S Storage in Deep Saline Aquifers: A Case Study from an Offshore Gas Field in Malaysia. From Lab to Numerical Simulation.
Authors: Zaidin M.F. , Valtz A. , Chapoy A. , Tewari R.D. 
Published: February 2024

Abstract
Most carbon dioxide (CO2) storage schemes rely on storing CO2 in its supercritical state, free from impurities (SNC-Lavalin Inc., 2004). The X field reservoir model, like many other existing reservoir models, assumes pure CO2 injection for its numerical simulation of CO2 storage. However, one of the gas sample analyses from the X field revealed the presence of trace amounts of hydrogen sulfide (H2S,) ranging from 500 to 1000 ppm. Given the limitations of the separation technology, there is a potential scenario where CO2 might be co-injected with H2S for storage. Understanding the impact of this H2S within the injected CO2 stream is crucial for ensuring the success of Carbon Capture and Storage (CCS) operations (Basava-Reddi et al., 2014; Wang et al., 2011). There is a possibility of CO2 being co-injected with this H2S for storage. The effect of the contaminant in the injected CO2 stream needs to be accessed to ensure the success of the CCS operation. The alterations in the base CO2 solubility can ultimately influence storage integrity and capacity (Ahmad et al., 2023). While abundant solubility data for CO2 in water or brine exist in the literature (A Chapoy et al., 2004; Valtz et al., 2004; Ahmadi & Chapoy, 2018), limited data are available for this ternary CO2- H2S-Brine system. Therefore, the need to quantify the impact of H2S impurities on CO2 solubility is evident. In this context, extensive laboratory experiments were undertaken to address these uncertainties and further refine the X field dynamic model for enhanced accuracy.
A Systematic Approach for Re-Fracturing Optimization and Horizontal Well Production Performance Improvement in Unconventional Resource
Authors: Tang Yongliang , Zhou* Wei , Zhou Daiyu , Zhang Jie , Wu Yiming , Wang Peng , Liu Zhiliang , Li Guohui , Lian Liming , Fu Xiaotao , Du Hongbao , Li Zheng , Huang Xingning 
Published: February 2024

Abstract
Re-fracturing of unconventional horizontal wells is currently one of the main measures to restore the production capacity of old wells in most oil and gas reservoirs. Different repetitive fracturing reforming measures have been adopted in a low-permeability reservoir in Xinjiang, and the reforming mechanism is still unclear. By establishing a geomechanical model, a pore pressure-induced stress change mechanism model based on the finite element method, and a numerical model for unstructured reservoirs, the fracture morphology of repeated fracturing and the effect of the reforming measures were studied and analyzed. The results show that the fracture morphology changes significantly after volumetric repeat fracturing compared with first fracturing and ordinary repeat fracturing. The change of stress orientation before and after production is insignificant, but the change of pore pressure and stress has a greater influence on the morphology of hydraulic fractures. For the layers that have been production, due to the large energy deficit of the formation, it is difficult to extend the fracture, with shorter fracture lengths and larger fracture widths, while when there is a recharge layer, the fracture is easier to extend due to the sufficient energy of the formation. Wells with a higher location of the infill layer can effectively increase the degree of vertical utilization of the reservoir, which has a better effect on increasing production. The timing of repeated fracturing has an obvious influence on the effect of increasing oil production, and timely repeated fracturing is more helpful in improving the oil production capacity of a single well.