bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increasing the Efficiency of Carbonate Acidizing: Kazakhstan Case Studies
Authors: Kalabayev Ruslan , Kruglov Ruslan 
Published: October 2020

Abstract
Hydrocarbon production enhancement by means of acid stimulation in Kazakhstan requires application of a more effective approach to address challenges associated with acid placement and reservoir contact in long pay zones of high-temperature carbonate reservoirs, thereby improving return on investment. Several robust chemical product solutions, coupled with comprehensive modeling in a new advanced simulator, have been successfully implemented to tackle the challenges and successfully increase the efficiency of matrix acidizing.
To improve the productivity of stimulated wells by improving the effectiveness of acid treatments, a detailed study of reservoir rock and its reaction to various acid and fluid systems has been made via laboratory testing and software modeling. Sensitivity analyses involving multiple treatment schedule scenarios incorporating various acid and diverter fluid systems are considered. Enhanced modeling of a novel retarded acid, viscoelastic diverting acid and particulate diverting systems demonstrated more uniform zone coverage, as well as deeper wormhole penetration. The above optimizations were field tested in several oil fields.
Prior to any acid stimulation, the formation injectivity and damage profiles were calibrated based on the well pre-treatment production profile taken from production logs. As the first step, performance of the retarded acid was tested in several treatments. The bottomhole injection pressure decline behavior indicated that a slower reaction takes place during injection of the retarded acid compared to the stages of conventional hydrochloric acid, confirming the retarded nature of the acid as seen from the core tests. Secondly, viscoelastic self-diverting acid was added to the schedule for treatment of long intervals, replacing conventional gelled acid with shorter viscosity peak and lower retained permeability features. Better zone coverage, observed from injection pressure slope changes upon arrival of each diverter stage downhole, and improved post-acidizing formation cleanup were achieved as a result of this implementation. Third, field trials were made using combined application of the viscoelastic diverting acid and degradable particulate diverter pills. Full and uniform coverage of the entire zone of interest has been observed after pressure matching the actual treatments’ schedule and was validated by post-stimulation production logs.
Field application of the approach supports the theoretical findings. Substantial improvement in well productivity was monitored after the application of each optimization step. The above approach demonstrates the value of thorough integration of laboratory testing, comprehensive software modeling and application of enhanced stimulation fluids. The efficiency of the approach is supported by multiple successful field case studies and is the recommended way forward for carbonate acidizing.
Modelling Unconventional Velocities from Acoustic Microscope Measurements
Authors: Simone Alessandra , Hathon Lori , Myers Michael 
Published: October 2020

Abstract
We use integrated micro-CT, thin section, XRF, SEM, and acoustic microscopy to quantify the controls on the acoustic properties of source rock reservoirs. At the smallest length scale a scanning acoustic microscope is used to measure velocities of individual laminae within unconventional samples. For unconventional reservoirs, in which typical particle and pore sizes are substantially smaller than 20 microns (i.e. the resolution of the acoustic microscope using a 20MHz probe), the difference in travel time between the first arrivals from the top and bottom surfaces of the sample provides an accurate measure of the velocity of each layer. The small feature size compared to the acoustic microscope wavelength eliminates the need for ray tracing.
To upscale this data, one inch diameter core plugs are first micro-CT scanned and their acoustic properties are measured as received. After CT scanning, end trim and axial thin section and SEM mounts are prepared. The entire end trim, or 1" axial slice, is ion milled in preparation for SEM and acoustic microscopy. Large area image mosaics are produced using low voltage SE imaging for characterizing porosity, and BSE imaging for characterization of organic content and mineralogy. Scanning CL imaging and image analysis are utilized to differentiate between detrital and authigenic phases. Energy dispersive x-ray mapping is also used for the identification of major mineral phases. The resulting suite of mosaic images are analyzed using University of Houston developed image analysis software. Segmented volumes of porosity, TOC, and mineral phases are determined for each layer type in the sample. After the SEM imaging is complete, the velocity of each layer type is measured on the same sample volume using scanning acoustic microscopy.
A Backus average of the measured velocities of each layer type agrees well with laboratory measurements made at the core plug scale for measurement performed perpendicular to bedding. We illustrate the correlations between segmented porosity, TOC, and mineralogy on the acoustic properties of each layer type. Mineral phases included in the modeling are clay minerals, pyrite, carbonate, and quartz. We include, where possible, the differentiation of authigenic quartz and detrital carbonate phases. Velocities for each layer type are mapped to the microCT data for the core plug. We illustrate the technique applied in several highly heterogeneous formations including the Niobrara, Haynesville, Barnett, Woodford, and Eagle Ford.
As maturity increases, the location of organic material will shift from predominantly bedding plane parallel oriented laminae, to interparticle pores, as kerogen is thermally altered to bitumen. This results in distinct changes in the vertical acoustic velocity signal and in the observed anisotropy. By observing changes in acoustic velocity signals and relating them to bulk mineralogy, TOC and maturity, models can be calibrated to determine the presence and distribution of organic material.
Reducing Crystalline Silica in Oilwell Cementing Operations
Authors: Jones Paul , Keeran Ryan , Osborne Paul , Ruiz Stephanie , Agapiou Kyriacos 
Published: October 2020

Abstract
Reformulating additives to reduce their crystalline silica content and modifying operational techniques are effective means for lowering worker exposure levels while maintaining additive performance. This is an important consideration as materials and methods used in operations are developed to reduce occupational hazards and maintain exposure to crystalline silica below permissible levels. A large opportunity to reduce crystalline silica dust in cement spacer additives exists based on annual consumption and mass fraction of crystalline silica in the additive.
Described herein is an approach to identify candidate additives for a cement spacer system that aligns with crystalline silica reduction efforts. Focus is placed on the evaluation of low crystalline silica spacer designs for efficacy in well cementing and successful application in field operations. The additive components considered for use in reformulated cement spacer systems are analyzed using X-ray diffraction to quantify mineralogy. After identifying low-crystalline silica components, an investigation of the rheology, wettability, and compatibility of the reformulated cement spacer is carried out over the application space by employing a full factorial and space-filling design of experiment techniques.
The reformulated cement spacer exhibits over 90% reduction in crystalline silica dust without sacrifice of rheological properties or material cost increase. The new low crystalline silica cement spacer (LCSS) has been validated in North American land operations. Bond logs confirm equivalent or better mud removal compared to previous cement spacers, with improved fluid interfaces and mud recovery. More than 2000 jobs have been performed with the new LCSS since introduction in January 2019 which corresponds to over 1.2 million pounds of crystalline silica dust eliminated from cementing operations.
Ten Years Forging Business, Management and Leadership
Authors: Capello Maria Angela , Buijs Hernan 
Published: October 2020

Abstract
The role of the Business, Management, and Leadership Committee (BMLC) of the Internatioal Society of Petroleum Engineers International (SPE) has been critical in raising awareness among SPE members regarding the need to develop and enhance interpersonal skills, which such skills are required in addition to "hard" or technical skills to effectively advance careers and sustain growth in the upstream oil and gas sector.
Endorsed at the highest level of SPE, the BMLC have consistently developed a series of activities providing a path of enrichment for SPE's membership of over 156,000 worldwide, in different languages and formats. This paper summarizes the journey of the BMLC, how the committee's work created a change in the perception of the importance of these skills, previously called "soft", to sustain success, and shares some best practices and learned lessons.
The need for enhancing and elevating management, business, and leadership skills is somewhat obvious to those who have experienced the impact these skills can have for advancing in a role, for fostering effective teamwork, for networking with colleagues of the same discipline, for securing a path to a promotion, and for being recognized for a compelling work performance. Historically, for individuals working in the upstream oil and gas sector, having excellent to outstanding technical skills suffices for recognition and reward, to add to this the need for business, management, and leadership skills is not an easy task.
Starting by the meager allocation of training budgets in corporations for non-technical training programs, and considering there is a prevailing bias that some skills like resilience or negotiation are inborn, there is no surprise in noting there is self-shame in admitting that one needs a course in – for example- stress control or similar personal skills. The open conversation about strong skills was needed within SPE, to support members to achieve more, leaving behind misconceptions that hamper success.
The journey of the BMLC has been challenging, and the compilation done for this paper surprised the authors, about the accelerated multiplication of benefits the BML has provided to SPE members. We will summarize some figures pertinent to the activities of the Committee, as well as some historical background on the launching and growth. We will also share what works for launching, maintaining and expanding similar programs for strong skills in corporate environments.
Anisotropy from Deep Directional Resistivity LWD Measurements
Authors: Wendt Brett , Akindipe Tunde , Alexander Malcolm , Hupp Douglas , Bourgeois Daniel , Leveque Soazig 
Published: October 2020

Abstract
Deep directional resistivity LWD measurements have been shown to be sensitive to resistive transitions over a broad range of distances around the tool from tens to hundreds of feet. These detected transitional surfaces are primarily used to detect formation resistivity boundaries and assist with mapping geological profiles. The inverted formation dip and vertical resistivities are also resolved in the same search space. While the formation dip is used in conjunction with the reservoir-mapping interpretation results, the vertical resistivity, specifically the vertical and horizontal resistivity ratio, or anisotropy, has not received the same amount of attention.
Resistivity anisotropy is useful when calculating the formation resistivity in layered formations, as conventional resistivity tools measure the resistivity in one direction, which is perpendicular to the tool axis. With conventional induction and propagation resistivity tools, the electrical current preferentially transits the conductive lithologies, resulting in an apparent resistivity measurement that does not represent the true sand resistivity. The petrophysical evaluation often results in an apparent high-water saturation, which can result in incorrect decisions to abandon a prospect.
To understand two new fields located onshore Alaska, three horizontal appraisal wells were drilled with deep directional resistivity LWD technology. While the primary goal was to characterize the lateral resistivity profile and bed boundaries away from the wellbore, accurate water saturation calculations along the horizontal section are critical for making appropriate development decisions.
A review on how and why deep directional resistivity LWD technology is sensitive to anisotropy and how anisotropy is derived from parametric inversions is presented with a comparison between deep directional resistivity LWD measurements, 3D petrophysical modeling of propagation, and offset well triaxial induction anisotropy measurements. Integrating 3D petrophysical processing and triaxial-induction technology into deep directional resistivity LWD measurements add to the strength of the anisotropy output. The comparison shows that deep directional resistivity LWD measurements can be used independently to give accurate anisotropy results.
The result of this process provides a corrected resistivity measurement of vertical and horizontal resistivity in anisotropic formations for petrophysical models. Use of the corrected resistivity as a true resistivity (Rt) input for water saturation will ultimately drive better development decisions.
A Novel Method of Non-Darcy Well Test Interpretation for Ultra-Low Permeability Reservoirs
Authors: Li Li , Liang Wei , Yan Zhenghe , Wang Kun , Luo Qiyuan , Li Qinquan , Xiong Qi , Chen Xiao 
Published: October 2020

Abstract
Conventional well test interpretation methods do not consider the special seepage characteristics of ultra-low permeability reservoirs, resulting in pessimistic well test interpretation of permeability and undervalued skin effect caused by reservoir damage. This study has established a well test interpretation model considering stress sensitivity/start-up pressure gradient and mud invasion for ultra-low permeability oil fields. The well test interpretation results have been applied to guide the formulation of overall development plan in South China Sea.
The mathematical expressions of stress sensitivity and start-up pressure gradient were obtained by using real core experiments. The quantitative characterization of mud invasion time-varying skin was realized by using numerical core experiments. Based on the new characterization method, a seepage model considering three factors above was established. The real space solution was obtained by using Laplace transform and Stehfest numerical inversion methods, a series of new standard plates were drawn, and corresponding ultra-low permeability well test interpretation software was compiled.
Based on the numerical simulator considering stress sensitivity and starting pressure gradient, an average permeability of 5md mechanism model with 0.6m near well bore damage zone was built. A well test design was then implemented to get pressure buildup data for well test interpretation. The authors compared the conventional well test methods and improved ultra-low permeability well testing method with same data base. A conclusion can be drawn that both permeability and skin have been seriously underestimated by using conventional well test methods. However, the permeability and additional pressure drop interpreted by improved ultra-low permeability well testing method is coincidence with mechanism model, which proved the validity of our new methods. Thus the well test permeability obtained by new methods can be used for productivity evaluation of low permeability oil field development and the skin factor can be used to guide mud system preparation and formation protection process design.
The influence of stress sensitivity/start-up pressure gradient and mud invasion damage of ultra-low permeability reservoirs have been pioneering discovered, and well test interpretation plates and software considering three factors above have been implemented for the first time in the industry.
Continuous Steam Distribution Optimization using Pattern Recognition on High Frequency Data Streams
Authors: Popa Andrei , Guerra Tomas 
Published: October 2020

Abstract
In this paper, an assessment of a streaming dataset from all active steam injectors in a mature steamflood field is carried out to understand and identify data trends and patterns which indicate if a steam injector is out-of-design. The dataset utilized in this study comprises real-time data and data in motion available thanks to the newly instrumented asset. However, this high-frequency data, while available, was never analyzed before this study. This work showcases the first study of this kind that utilized high-frequency streaming data from steam injectors. As an exploratory study, it revealed powerful insights and patterns which explained not yet understood behaviors. The methodology employed involved management and analysis of large volumes of data and consideration of the steam distribution system network. The study revealed the root causes of out-of-design and questionable steam quality values, which led to a comprehensive report describing the events, recommendations, and remedial actions for 33 out of 111 active injectors. The business driver for this project relies on solving cases in which the real steam quality is unknown, or the injector is out-of-design, which affects the steam-flood delivery and, consequently, the oil production performance. The novelty of this study relies on the capability of identifying undesired events at very early stages. In similar oilfields under steam-flood operations, steam injectors performance is tested and analyzed every three to six months. Many undesirable events may occur and are ignored in the time window between tests. The study not only led to business value impact due to addressing un-optimized injectors but also started a new program for real-time monitoring.
This research demonstrates the value of using high-frequency raw data for steam injectors diagnosis, management, and monitoring.
Modeling and Upscaling of Viscous Fingering during Unstable Drainage Displacements
Authors: Zhao Bochao , Mohanty Kishore 
Published: October 2020

Abstract
Viscous fingering is a common phenomenon in viscous oil waterflooding, gas flooding and carbon sequestration processes. Wettability has been shown to have a significant effect on viscous fingering. The objective of this research is to model viscous fingering during drainage displacements, i.e., a non-wetting phase displacing a viscous wetting phase. We modified a previously proposed effective-fingering model for imbibition processes. Laboratory unstable coreflood experiments were history matched. Power-law correlations were developed between history matched model parameters and physical parameters such as the velocity and viscosity ratio. Fine-grid intermediate scale simulations were conducted with the effective-fingering model for domains with different degrees of heterogeneity. Coarse-grid simulations were run to determine the shape factor (one of the effective-fingering model parameters) needed to match the result of fine-grid simulations. The shape factor is a function of the correlation length, Dykstra-Parsons coefficient and viscosity ratio. This correlation can be used to upscale the interaction between viscous fingering and channeling in large scale simulations.
Study of Oil Recovery Mechanisms in Complex Natural Fracture Systems using Embedded Discrete Fracture Models
Authors: Vo Hai , Mallison Brad , Kamath Jairam , Hui Robin , Dufour Gaelle 
Published: October 2020

Abstract
Accurate evaluation of recovery mechanisms in fractured reservoirs is challenging due to the large permeability contrast at the matrix-fracture interface. Dual Porosity-Dual Permeability (DPDK) models are typically used in field-scale simulations but can be biased by their use of idealized fracture networks and matrix-fracture interactions. Unstructured Discrete Fracture Models (USDFMs) are able to capture the complex physics accurately but can be computationally demanding. Embedded Discrete Fracture Models (EDFMs) integrate discrete fracture networks with a structured matrix grid and are the focus of this study.
Our study considers dense and sparse fracture networks extracted from a field-scale fracture carbonate reservoir model. EDFMs are constructed for different matrix grid resolutions, and simulations are performed to evaluate gravity drainage, spontaneous imbibition, viscous displacement. In each case, EDFM results are compared with highly refined USDFM reference solutions and equivalent DPDK simulations.
We improve the EDFM single phase matrix-fracture transfer function to account for pseudo-steady state and fracture interactions. In the cases of gravity drainage, EDFM simulations converge to the fine scale reference solutions with matrix grid refinement. For the coarser grids, the new matrix fracture function gives much better results than the ones reported in the literature. For spontaneous imbibition, both EDFM and USDFM overpredict the rate of spontaneous imbibition with coarse matrix grids, but the overestimation is less severe than with DPDK. In viscous displacements, EDFM overestimates recovery with coarse grids and displacement efficiency diminishes with refinement. DPDK underpredicts recovery from viscous displacement at all resolutions.