bluuebunny/crossref_metadata_2025 huggingface dataset:
A STATISTICAL META-ANALYSIS OF LITHOLOGIC AND OTHER POTENTIAL CONTROLS ON FOSSIL BONE CELLULAR AND SOFT TISSUE PRESERVATION
Authors: ULLMANN PAUL V., , SCHWEITZER MARY H.,
Published: June 2023

Demineralization assays, utilizing weak acids to isolate organics from biomineralized tissues, have recently been applied with increasing frequency to explore soft tissue preservation in fossils, revealing frequent retention of cells and other pliable microstructures in fossil bones. However, factors controlling long-term preservation of such labile structures remain mysterious. To address this, we compiled a database of bone demineralization results from 29 studies, then conducted a statistical meta-analysis of these data to evaluate the importance of specimen age, taxonomy, entombing lithology, and bone tissue type on microstructure recovery. Our database encompasses results from 137 bones from 44 formations spanning the Permian to the Holocene. Osteocytes, blood vessels, and fibrous/proteinaceous matrix each exhibit bimodal recovery patterns in which most fossil bones either yield many or none of these microstructures. Though their relative abundances in any given fossil bone are extremely variable, statistically significant Fisher's Exact tests found that if a bone yields one of these types of microstructures in abundance then the others are usually also abundant. None of the variables examined significantly influence osteocyte recovery, but Kruskal-Wallis and subsequent pairwise Mann-Whitney tests revealed that bones collected from unconsolidated sediments, of Paleocene age, and/or deriving from birds, amphibians, marine reptiles, or crocodylians often yield few or no vessels and fibrous matrix. Although these findings hint at possible controls on cellular and soft tissue preservation in fossil bones, they should be viewed cautiously as they are demonstrably biased by uneven sampling. For example, many of the apparent trends are substantially controlled by overrepresentation of data from nonavian dinosaur specimens from Cretaceous fluvio-lacustrine deposits. Future demineralization assays should therefore focus on non-mammalian specimens from the Cenozoic and Jurassic-and-older nondinosaurian specimens, especially those preserved in less-common depositional environments (e.g., eolian settings).
Effect of biopolymer composition on the viability of Trichoderma sp. as maize-seed coating
Authors: Arsyadmunir Ahmad , Pawana Gita , Badami Kaswan , Sholikhah Nuriatus , Wuryandari Yenny
Published: June 2023

Trichoderma spp., is a fungus with the ability to control disease and promote plant growth. The mechanism is through the activity of microparasites, antimicrobial secondary metabolites, phytohormones and mobilization of plant nutrients for plant growth and production. The purpose of this study was to examine the biopolymer composition as a seedcoating formula on corn seeds with Trichoderma as the active ingredient, namely to obtain a biopolymer composition that is able to maintain viability and inactivate Trichoderma during storage. Completely randomized design was used with a single treatment factor for the composition of the formula, i.e.; K1 is control 1 (suspension of conidia Trichoderma sp.); K2 is xanthan gum 2.5% + Na alginate 2.5% + conidia suspension Trichoderma sp. + talk; K3 is xanthan gum 5% + Na alginate 5% + conidia suspension Trichoderma sp. + talk; K4 is xanthan gum 2.5% + CMC 2.5% + conidia suspension Trichoderma sp. + talk; K5 is xanthan gum 5% + CMC 5% + conidia suspension Trichoderma sp. + talk; K6 is Na alginate 2.5% + CMC 2.5% + Trichoderma sp. conidia suspension. + talk; K7 is Na alginate 5% + CMC 5% + conidia suspension Trichoderma sp. + talk; K8 is control 2 (suspension of conidia Trichoderma sp. + Talc). The results obtained showed that the composition of the seedcoating formula consisting of 5% xanthan gum + 5% Na alginate + Trichoderma conidia suspension + talc up to 60 days after application of seedcoting on seeds could inactivate Trichoderma reproduction, but could not suppress the decrease in viability.
Kekerasan Seksual dalam Perspektif Dominasi Kuasa
Authors: Nugraha Ryan Aldi , Subaidi Subaidi
Published: June 2023

Penelitian ini bertujuan untuk menganalisis kasus kekerasan seksual yang terjadi berdasarkan perspektif dominasi kuasa, di mana kekerasan seksual terjadi dalam lingkup pendidikan formal dan informal yang cenderung struktural; antara orang yang menguasai (powerful) dan orang yang dikuasai (powerless). Kemudian menganalisis kondisi-kondisi kebergantungan dilihat dari motif kronologis kasus. Penelitian ini menggunakan Metode kajian literatur. Data diperoleh dari Catatan Tahunan Komnas Perempuan, SIMFONI-PPA (Sistem Informasi Online Perlindungan Perempuan dan Anak), dan portal berita nasional teraktual. Berdasarkan data yang dihimpun oleh SIMFONI-PPA pada tahun 2021, diketahui bahwa kasus kekerasan dan pelecehan sebanyak 59,2% terjadi di dalam rumah tangga, 26,9% terjadi di lingkungan pendidikan formal - informal, dan 13,6% terjadi di tempat kerja dan fasilitas umum. Dari 21.000 lebih jumlah korban kekerasan dan pelecehan seksual, ada 19,9% korbannya adalah laki-laki, dengan 60% korbannya adalah pelajar laki-laki. Hal ini mengindikasikan bahwa kasus kekerasan dan pelecehan seksual tidak terobjektifikasi pada gender tertentu. Di lingkungan pendidikan formal maupun informal, motif yang dipakai pelaku seringkali memanfaatkan kuasa dan kondisi kebergantungan untuk melakukan tindakan pelecehan.
Hydrocarbon Production Enhancement on the Field Apaika-Nenke by Applying Hydraulic Fracturing as a Tool to Optimize the Extraction of Reservoir M-2 Considered Initially as a Secondary Target
Authors: Salazar F. , Vasconez N. D. , Mayorga C. J. , Pozo M. F.
Published: June 2023

Due to reservoir conditions in the Apika-Nenke field, it was decided to carry out a hydraulic fracturing pilot project with the aim of maximizing production in the field. To achieve the objective, cores, image logs, pressure points, and sonic dipole logs were obtained to have the greatest amount of information available during the analysis and thus stimulate the reservoir to obtain the maximum potential.

After the analysis of the laminated reservoirs, it was required to implement a technique that generates higher fracture conductivity to reduce the drawdown during production and improve the connection through the laminations. The successful implementation of channel fracturing led to this technique becoming the preferred completion method in the field for wells requiring stimulation.

Three hydraulic fracturing treatments were performed in Apaika-Nenke field: one in 2015 and two in 2022. With continuous improvement in the perforating and fracturing technique, all jobs demonstrated outstanding production results. The implementation of hydraulic fracturing permits the production of this reservoir, which was considered a secondary target due to the low production results without fracturing.
Winning the Battle to Scale Precipitation from the Face of T Reservoirs in the Largest Ecuadorian Oilfield
Authors: Paredes M. P. , Estevez D. R. , Sepúlveda W. M. , Giol C. G. , Zumbana V. , Tamayo P. , Andrade R. , Sotomayor A. , Egas L.
Published: June 2023

The largest Ecuadorian field is a brown field located in the Oriente Basin, as shown in Fig.1. Its current oil production is 56,000 bopd with 82% water cut from 150 producing wells from different reservoirs, mainly from the lower U and lower T sands which have contributed with more than 90% of the total cumulative production. The secondary reservoirs are Basal Tena, Upper U and Upper T.

The field faces several typical production challenges of a mature field, including severe inorganic scale deposition problems throughout the production system and corrosion in the tubing and surface flowlines. As development strategies have evolved, flow assurance problems have increased in magnitude and frequency, representing low operating efficiencies and extra costs.

Once flow assurance problems have appeared in the field it is impossible not to have costs associated with their remediation; however, the objective is to minimize such costs through an exhaustive analysis that determines the root cause and the prevention measures that can be applied in the field. In terms of corrosion, an excellent job has been done in controlling the problem in the wells through the introduction of new metallurgy tubing and good operating practices, while the challenge in the field is now focused on scale deposition.
3D Real Time Digital Twin
Authors: Ferrigno E. , Barsola G. A.
Published: June 2023

The term Digital Twin, referring to the digital representation of an indistinguishable physical system or process in the real world, is a relatively new technology that has gained attention in recent years due to its potential to improve efficiency and decision-making in various industries. The concept behind Digital Twins is to create a virtual replica of a physical asset or process, allowing for real-time monitoring, data analysis, and simulation of different scenarios. This technology can be applied to various industries such as manufacturing, construction, and oil and gas.

In the oil and gas industry, Digital Twins can provide several benefits. For example, they can improve operational efficiency by providing real-time data on the performance and condition of assets, allowing for better decision-making and reducing downtime. Additionally, Digital Twins can also help with asset management by providing detailed information on the performance and maintenance requirements of assets, which can be used to optimize their operation and extend their service life. Furthermore, Digital Twins can also be used to simulate the performance of new assets before they are built, reducing the risk of errors and increasing the chances of success.

One of the key aspects of Digital Twins is that they can be updated in real-time, allowing for continuous optimization of the system. This is achieved by integrating various technologies such as sensors, IoT devices, and machine learning algorithms, which provide data on the physical asset and its environment. The data is then processed and analyzed, providing insights that can be used to improve the performance of the asset.
Combining Data Acquisition, Control, Monitoring Systems and Physics Simulation in an Autonomous Way, to Locate and Minimize Inefficiencies in Gas Processing Facilities
Authors: Aladin Zayn , Meinhardt Amin Adolfo Claib , Schepens Gerald
Published: June 2023

The demand for additional throughput, combined with the growing pressure to reduce CO2 emissions while, improving efficiency constitutes a significant challenge for the oil and gas industry. Changes and updates to process models attempt to address these challenges but have mostly served as design aids rather than operational tools. Simulations, machine learning and artificial intelligence can be used to model plant start-up / shut-down, facilitate optimization and alleviate bottlenecks, however, these tools help to make inferences about processes; real-world deviations between the actual process and input data in a model limit their practicality.

Throughput Optimization uses 150 years of physics based thermodynamic modelling, directly integrated into existing plant infrastructure, to provide advanced process control in real-time. Allowing the operator, the possibility of leveraging existing infrastructure and enabling closed-loop and/or human supported control. Results include hydrate formation avoidance through the analysis of real-time phase envelopes and hydrate curves, increased NGL production, greater control of operating costs and reductions in unscheduled downtime.

Throughput Optimization has proven to enable more optimal control for operations and demonstrated various benefits, including reduced operational costs, increased revenue, improved operational reliability and reduction in both Scope 1 and 2 emissions.
Production Rate Calculation Using Choke Correlation, Improving Matching Field Data on Vaca Muerta Formation.
Authors: Bellini Aragon Nicolas Gabriel , Villagra Fernando Martín , Serrano German Dario
Published: June 2023

Usually when the Production Engineer needs to follow a DrawDown Curve to maximize production of the well, a methodology to calculate dynamic pressure at sand face (PWF) is needed.

To calculate PWF, the Gas and Liquid Rate and wellhead conditions need. On many occasions, there is no separator to run a production test so, as a consequence, a methodology to calculate production rates becomes vital.

This paper uses the choke correlation developed by Bellini et al. to calculate total mass and use a workflow to find Water Cut and GOR using Equation of state to split total mass in Gas, Oil and Water mass, and transform them to volumetric rates.

In Non-Conventional fields, wellhead chokes are widely used to, for example: regulate the flow rate of the well, to impose sufficient back pressure on the face of the sand so as not to exceed values excessive drawdown.

Many authors use choke correlation to find Gas or Liquid Rates but not all at same time and uses many times wrong correlation with error higher than 20%.

The workflow presented in this paper, combines high confidence multiphase choke correlation to predict mass rate and use Equation of State (EOS) to predict GOR and Water Cut relations, this combinations of both make sure best confidence calculations.

This new workflow was tested with several oil wells at non-Conventional reservoir and its performance is more confidence to existing methodology used nowadays.

The Volumetric rates calculation need to use the best technical practices combining fluids thermodynamic and production knowledge to reach the minimal error we can do.

Examples and back test of volumetric rate calculation vs separator measurements on wells from "Vaca Muerta" Formation, will be compared a showed as result of this job.

Finally, an application of Well performance analysis will be showed, in order to evaluate choke sensitivities to maximize liquid production rate and maintain Well DD into optimal Drawdown Curves to make sure maximize EUR as we can.
Improving Oil Recovery while Helping to Achieve Net Zero Emissions from Shale Reservoirs
Authors: Bao Xiaolin , Fragoso Alfonso , Aguilera Roberto
Published: June 2023

Shale reservoirs will help to meet oil demand that is forecasted to continue increasing for several years. Oil recovery from shales is low and has been reported to range between 5 and 10%. The objective of this paper is to show how oil recovery from shale can be improved while simultaneously reducing CO2 emissions, contributing thus to the goal of a Net-Zero future.

The proposed methodology shows how oil recovery from shales can be increased while simultaneously storing CO2 in undepleted (as opposed to depleted) shale oil reservoirs, and consequently contributing to a future with Net-Zero emissions. The methodology is developed with the use of reservoir simulation, and is achieved by performing the following procedure: (1) start huff 'n' puff CO2 injection, 2 or 3 years after the well goes on oil production; thus, the shale reservoir is undepleted, (2) store CO2 gradually in the shale reservoir during the huff periods, and continuously once the huff'n'puff project is finalized.

The simulation model includes a history match period with actual production data from a pilot horizontal well, and a forecast period with huff 'n' puff CO2 injection. Two cases, one with diffusion and one without diffusion are carried out for evaluating the molecular diffusion effect. The initial pressure is never exceeded.

Our literature survey indicates that the methodology proposed in this paper has not been considered previously in the geoscience of petroleum engineering literature. The proposed approach will help to achieve Net-Zero emissions by storing CO2 in undepleted shale reservoirs while simultaneously increasing oil production. This win-win combination, to the best of our knowledge, is novel.
An Innovative Combination of Thermal Enhanced Oil Recovery Process with Organic Rankine Cycle to Improve Energy Efficiency
Authors: Rodriguez H. A. , Perez R. A. , Guerrero J. E. , Garcia L. E. , Manrique E.
Published: June 2023

Most thermal enhanced oil recovery (tEOR) processes worldwide are trying to be optimized due to the energy transition and greenhouse gas reduction plans. In that sense, reducing natural gas as a fuel for steam generation and improving the energy injected vs. energy produced represent key drivers for heavy oil exploitation. Colombian case is not different; the challenge plans to reduce 51% of CO2 emissions by 2030 will require technology incorporation and disruptive ideas. Ecopetrol is evaluating the concept of in situ steam generation assisted by the mist water-air injection and combining this tEOR process with organic Rankine cycle (ORC) equipment to take advantage of produced fluids to generate electricity. The process involves simultaneous air and water injection into the formation, in mist-like flow generated at wellhead, promoting a combustion front development, and using the injected and reservoir water for the in-situ steam generation. This represents an impacting reduction in the use of natural gas as a fuel for traditional steam generation processes. A numerical model was developed to evaluate the injection scheme and forecast oil production, fluid temperatures, and produced energy. The sector model allows the identification of optimum scenarios regarding appropriate water-air injection rates and enthalpy to obtain the best incremental oil recovery, energy efficiency, and low carbon intensity. The results indicated that with mist water-air injection, the recovery factor increased between 30 to 45%, and the peak of produced power was double (up to 4 MW) compared to the conventional steamflooding scenario. Since natural gas is not required, carbon intensity reduction is between 30 to 60%. Additionally, combining oil produced by the mist water-air injection and power generation using ORC, the total energy recovery factor is 50%. This paper presents an innovative concept for in-situ steam generation coupled with ORC technologies. This combination led to better use of the heat transferred into the formation and reduced natural gas and water consumption. Additionally, the use of produced hot fluid represents an integrated process of enhanced energy recovery (EER) as a strategy to partially overcome high carbon intensity estimations in traditional processes and avoid stranded assets. Carbon intensity can be further reduced by incorporating Carbon Capture Usage and Storage (CCUS) strategies met Colombian energy transition plans.
Measurement of CO2 Solubility and Swelling Factor in Water/Brine for CO2 Sequestration
Authors: Fayazi A. , Maaref S. , Esmaeili S. , Kantzas A.
Published: June 2023

CO2 dissolution in water/brine at various operating conditions is of essential interest for various environmental and geochemical applications such as CO2 sequestration in brine-bearing aquifers. Solubility/swelling in CO2-brine systems can be determined by experimental data or the available correlations and modelling packages. However, the available models and correlations can only be used in limited situations, and therefore, may not be applicable for a wide range of operating conditions, particularly for different salinities. In addition, the available solubility and swelling experimental data in the literature are limited as these experiments are very time consuming due to the slow nature of the diffusion process. Therefore, reliable experimental data is needed especially in the range of operating conditions suitable for CO2 storage scenarios. In this work, a high-pressure high-temperature (HPHT) visual cell with a novel stirring mechanism was designed to accelerate the diffusion process at elevated pressures and temperatures. A series of swelling/solubility tests are carried out for a CO2–brine/water system at various equilibrium pressures ranging from ~ 3000 to ~ 12000 kPa and temperatures ranging from 35 to 55 °C and with different salinities. The process of CO2 dissolution results in a pressure decline and volume expansion (swelling) of the liquid phase over time. Swelling is measured by tracking the gas-liquid interface using a microscope camera and solubility is measured by monitoring the pressure and performing PVT analysis. In the absence of stirring, the CO2 dissolution takes a long time, however, the use of stirring expedites the dissolution process. Thermodynamically, we have an instantaneous equilibrium at the gas–liquid interface and the equilibrium concentration at the gas–liquid interface is the maximum concentration of dissolved gas (i.e., solubility) in the liquid. The diffusion which controls how quickly the gas dissolves in the liquid slows downs the overall process. The high-pressure stirring mechanism creates convection in the liquid and accelerates CO2 dissolution. The results also revealed that increasing the pressure, decreasing the temperature, and decreasing the brine salinity increases the swelling and solubility of CO2.
High Performance Water-Based Fluid Replaces Oil-Based Mud on the Execution of a Complex 3D Well Trajectory in Aguarague National Park, Bolivia
Authors: Rojas Danny , Soruco Andrea , Jimenez Carlos , Soriano Victor , Ahmed Ramadan
Published: June 2023

The South Sub-Andean Bolivian Basin hosts Aguarague National Park, which prohibits the use of oil-based mud due to its high environmental sensitivity. In response, the drilling team selected a high-performance water-based fluid as the mud system for the 16-inch hole section. The objective was to manage engineering and operational issues related to reactive shales and hole inclination. Lessons learned from an appraisal well drilled in a complex 3D trajectory are presented in this article.

The drilling team designed an appraisal well with two main objectives: to drain hydrocarbons from the main structure and limit reservoir extension. To accomplish these goals, they designed a high-angle S-shaped 3D well, including a 16-inch hole section with an inclination of up to 50 degrees and a slight turn to align geological targets. The section consisted mainly of 1000 m of challenging shale formation at an unfavorable target angle. Moreover, the team used high-performance water-based mud due to environmental constraints in the area.

The drilling team drilled 1250 m of the 16-inch section through high reactive shales without any wellbore stability issues, thanks to accurate density control and suitable mud additive concentrations, such as biopolymers or synthetic polymers. The mud met lubricity requirements and reduced drilling torques. The synergy of the key drilling fluid components produced stable rheology and low fluid loss, proving to be a cost-effective alternative to oil-based mud in environmentally sensitive areas. The team achieved the planned trajectory without major problems, meeting the estimated schedule. The well was completed on time and within budget, and wireline logs were able to survey the open hole without issues. Finally, the 13,375-inch surface casing reached the bottom and was cemented in place successfully.

The drilling team successfully used a high-performance water-based mud system to drill complex 3D well trajectories in the South Sub-Andean Bolivian Basin, despite environmental constraints. The operation's success in achieving well objectives depended on appropriate mud formulation and maintaining the right concentration of shale inhibitors.
Improving Acid Coverage in a Naturally Fractured HPHT Carbonate Reservoir by Combining Chelating Fluids and Chemical Diversion Optimization
Authors: Velázquez Diana L. , Tellez Fernanda , Ramírez Carmen J. , Fragachán Francisco E. , Omer Mohammed , Figueroa Frank , Mejias Gustavo , Brito Bonifacio
Published: June 2023

Uniform distribution of stimulation fluids in a naturally fractured reservoir with high permeability contrasts and a long open hole configuration (more than 800 m) requires an efficient temporary blocking of the preferential zones to allow the fluid to be diverted towards zones with less admission. While having bottomhole temperatures above 175°C means that controlling reaction rates and achieving effective etching to allow appropriate penetration into the invaded zone will be required and thus eliminate skin damage caused during drilling and completion. Therefore, accomplishing the optimal stimulation involves improving not only acid etching efficiency, natural fractures connectivity and adequate fluid penetration, but also achieving homogeneous fluid distribution throughout the interest zone to assure production enhancement.

A chelating base fluid system was formulated based on reservoir evaluation through an engineering process that involved numerous laboratory tests, such as rock dissolution capability, acid etching patter analysis, acid spending time evaluation, corrosion control, and compatibility with reservoir fluids, while optimal diverting agent was carefully selected using advance CFD modeling to confirm diversion effectiveness to uniformly distribute fluids under bottomhole conditions and complex well configuration. Finally, stimulation treatment was defined considering fluid invasion, skin removal and productivity analysis. This paper discusses laboratory tests and modeling results as a coupled engineering process to improve acid coverage during an actual implementation in a HPHT well.

Laboratory results confirmed that the smart fluid system can create long conductive channels increasing conductivity by dissolving rock formation and prevent by-products precipitation. On the other hand, CFD results demonstrated that the application of multi-stage chemical diversion pills at specific conditions (flow rate, volume, rheology) optimizes fluid distribution.

Oil production increased from 3,973 to 4,375 BPD and gas production from 10.0 to 13.4 MMSCFD (½"choke) after executing the stimulation job. Wellhead pressure registered before was 3,845 psi, and after the job increased up to 5,276 psi. Successful stimulation was confirmed with bottomhole conditions which showed an increase of 2,045 psi and 5°C, logged through a bottomhole sensor while the productivity analysis allowed to support skin damage reduction from S=76 to S=0.
A Comprehensive Approach to Organic Precipitation Damage by CPA EoS from Monte Carlo, and Machine Learning Methods
Authors: Cundar C. , Guerrero-Benavides C. , Aristizabal J. D. , Moncayo-Riascos I. , Rojas-Ruiz F. A. , Orrego-Ruiz J. A. , Cañas-Marín W. , Osorio R.
Published: June 2023

In this study, an integrated machine learning (ML) model was proposed that allows to identify the risk of organic precipitation damage and estimate the asphaltene onset pressure (AOP). In addition, an estimation of the association parameters to estimate the AOP using a Cubic-Plus-Association (CPA) equation of state (EoS) using stochastics (Monte Carlo) and ML approach was carried out. To predict the asphaltene damage risk the asphaltene stability class index (ASCI) data and the in-situ live crude oil densities were used along with the support vector machines (SVM) method. To propose the AOP-ML model a dataset of 53 samples was considered, evaluating different ML methods. In both cases, 80 % of the dataset was used to train the model, whereas 20% was to validate it. In the Monte Carlo (MC) simulations, 6 fluids taken from literature were used. The ML classification model had a perfect accuracy (100 %), which was compared to conventional compositional asphaltene screening models, with a classification accuracy of 33% for the resin/asphaltene ratio, 29% for ASI, 67% for CII, and 88% for de Boer plot. The AOP-ML model described properly the 77% of the variation of the experimental AOP of the 6 fluids evaluated using a stepwise bidirectional linear regression with 9 input features. Finally, the MC results indicated that several combinations of association energies and volumes reproduce the experimental AOP, obtaining a linear model for estimating the cross-interaction energy with a coefficient of determination of 0.934. This study provides disruptive findings since it opens the possibility of formulating predictive EoS, obtaining the association parameters from a fluid's compositional and structural characteristics. This approach is an opportunity for a comprehensive understanding of asphaltene precipitation damage that allows to understand the mechanisms of formation damage and therefore look for promising solutions to restore the productivity of fields affected by asphaltene precipitation formation damage.
Practical Aspects and Implications of Long-Term CO2 Sequestration in Saline Aquifers Using Vertical Wells
Authors: Moridis G. J. , Reagan M. T. , Huang T. , Blasingame T. A.
Published: June 2023

The primary objective of this work are (a) to analyze the impact of salinity on the attempt to sequester CO2 in saline aquifers by means of vertical wells over long times—covering both the early short injection period and the subsequent long ‘rest’ period of inactivity—by determining its effect on key well and aquifer properties, conditions and rates of mass and heat transport, and (b) to investigate possible methods to mitigate the problems caused by salt precipitation (halite). We use a widely used numerical simulator that accounts for all the multiphase flow and transport processes associated with CO2 sequestration, including halite precipitation. The non-isothermal simulations use a high-definition cylindrical grid with radial subdivisions as small as 0.01 m in the vicinity of the well to accurately capture the critically importance effect of halite precipitation (the evolution and impact of which may be eluded when using coarser grids). Using two different well configurations of vertical wells, we inject CO2 as realistic rates into aquifers with varying salinity levels until a geomechanically safe maximum pressure is attained, and allow the system to rest for 100 yrs. During the entire simulation period, we monitor the evolutions of (a) pressures and temperatures in the near-well region and in the entire aquifer and (b) of mass and heat losses through the overburden. Additionally, we investigate possible methods to alleviate injectability problems caused by halite precipitation. The study shows that (a) wells completed in the entire aquifer depth are more effective in low-salinity aquifers, but shorter wells completed at the base of the aquifer are superior in high-salinity cases, (b) the storage potential of CO2 dissolved in the aqueous phase is limited (both in terms of the magnitude of the dissolved concentration and its spatial extent), and its benefit decreases rapidly with an increasing salinity, (c) salinity can have pronounced adverse effects on the well injectivity, as halite precipitation can cause severe blockage in the vicinity of the well and a rapid rise of the near well pressure to geomechanically unsafe levels, thus potentially reducing the usefulness of an aquifer as a CO2 storage facility and (d) the mitigation of the effects of precipitated halite in the well vicinity is a challenging endeavor, with concurrent H2O-CO2 injection being ineffective.
Tailored Cement Spacer System Improves Barrier Dependability in High Permeability Reservoir Sections in Colombia
Authors: Arroyave Juan Manuel , Paredes Jose Luis , Castro Fabian , Agapiou Kyris , Barreto Diogenes , Vela Jose David , Lopez Alexander , Guzman Leonardo , Fiaga Maria Anayibe , Garcia Nelson
Published: June 2023

Lost circulation (LC), commonly encountered during oilwell drilling and cementing, can be a costly problem that increases non-productive time. LC is especially concerning in high permeability reservoir sections. When LC occurs during cementing, poor annular coverage and cement fall back may occur which results in an undesired top of cement and the need for remediation.

Described herein is the use of a new tailored spacer fluid system engineered to effectively mitigate LC or seepage losses while preparing the wellbore to receive cement.

Ecopetrol S.A, the National Oil Company in Colombia was concerned about cementing production liners in highly permeable, depleted sandstone sections of a formation. The challenges included permeabilities from 7-8 Darcy, lost circulation events, and unacceptable hydraulic seals according to cement evaluation logs resulting in remedial operations. Managed Pressure Drilling (MPD) was an initial solution.

As part of the best cementing practices to meet this objective, designing and tailoring of the spacer needs to be taken into consideration. Optimum tuning allows the cement to cover zones of interest and reduce contamination such that the cement properties can develop and bond with the formation in an efficient way.

A new spacer system was designed to optimize cementing jobs, the tailored spacer system utilizes additive synergies to help prevent LC in porous or fractured formations and enable control of rheological hierarchy and wellbore fluid displacement efficiency.

Use of the new cement spacer system with the tailored approach enabled flawless execution per the job design. The spacer exhibited excellent rheological behavior to meet and maintain hierarchy requirements. Cement was circulated to the top of the liner.

After performing the cementing operation, LC was not observed. Cement bond log (CBL) and variable density log (VDL) results confirmed zonal isolation objectives were achieved. Operations with previous wells in the same field required remedial squeeze jobs to complete. In this case, the Tailored Cement Spacer System helped eliminate the need for remediation, allowing a significant cost saving opportunity on these wells.

The new spacer system successfully employed in high permeability formations in cementing operations in Colombia allowed savings for the operator and helped improve barrier dependability.
A Novel Workflow to Design Cementing Fluids for Loss Mitigation
Authors: Jandhyala Siva Rama Krishna , Yerubandi Krishna , Jimenez Walmy Cuello
Published: June 2023

Lost circulation remedial techniques will be effective when they are tailored for the specific challenge. Examples of factors that govern the remedial technique are the type of losses (induced vs. natural fractures, permeable formations, etc.), characteristic size of loss zone, difference between equivalent circulation density and pore pressure gradient, etc. Typically, localized workflows are designed based on experience from wells where these factors are within certain limits. These workflows are limited to the new wells where these factors are within the same limits. Additionally, these workflows usually involve the selection of certain type/size of lost circulation materials (LCMs) with less emphasis on tuning fluid density, rheology, and pump rates. A comprehensive approach, one that caters to a wide range of loss scenarios and allows tuning all engineering parameters available for tailoring the unique solution is needed.

The work method discussed herein is built using the principles of mass and momentum conservation. These hydraulic calculations also account for rheology changes due to temperature. The domain of analysis is both the wellbore and the loss zone. Thus, any changes in the wellbore will impact the loss rate and vice-versa. To such a two-way coupled system, a cake buildup model is added in the loss zone to describe the role of filter cake resistance on loss rate. Thus, the proposed method is the most comprehensive approach available to model losses based on wellbore pressures, temperatures and plugging of the loss zone. Such a method allows for greater design flexibility to the engineer in tailoring wellbore fluids during drilling or cement operations.

The proposed method is used to understand the sensitivity of the loss zone size to the loss type, loss rate and the depth at which losses occur. This helps engineers highlight the critical information needed from job location to tailor the remedial treatment. The effect of loss zone size on the efficacy of an LCM is demonstrated by evaluating the performance of LCMs of different size and shape. This analysis is useful in tailoring blends made up of different LCMs. Moreover, this work method is used to also compare the impact of rheology and density modification vs. LCMs addition on loss control. This provides greater flexibility in tailoring different aspects of wellbore fluids and placement characteristics.

The understanding gained from the above analysis is used in predicting the loss control performance across multiple jobs. These jobs varied in loss rate and loss type. The proposed methodology presented herein revealed an optimum match with actual field observation for all the evaluated jobs. For an example job, the model was able to predict the observed surface pressure. All this analysis further demonstrates the capability of the work method in combating losses by tailoring different aspects of a cement job.
Numerical Simulation of Cyclic Steam Stimulation and Solvents Enhanced With Nanocatalysts: A Methodologic Approach
Authors: Ruiz-Cañas M. C. , Garcia-Duarte H. A. , Perez-Romero R. A. , Manrique E.
Published: June 2023

One of the alternatives to optimize conventional Thermal EOR is using hybrid technologies such as the combination of steam and solvent enhanced with nanomaterials. Due to the necessity to evaluate nanocatalysts' impact in this hybrid technology, it is necessary to forecast different injection scheme scenarios. This work shows a numerical simulation methodology approach for evaluating the impact of including nanocatalysts in Cyclic Steam Stimulation (CSS) supported by experimental data obtained from previous steam-based hybrid evaluations.

Based on viscosity curves, phase behavior of reservoir fluids and solvent enhanced with nanomaterials, thermogravimetric tests at high pressure, fluid-fluid and fluid-rock tests, and properties of produced oil samples, among others, it was possible to determine kinetic properties required for the construction of the numerical simulation model of the steam-based hybrid technology. The methodology includes the evaluation of injection scheme scenarios to compare the hybrid Cyclic Steam Stimulation (CSS) - solvent with nanoparticles and conventional CSS.

Supported by the experimental results of the hybrid technology and the study of the phenomena involved in this thermal EOR process, a procedure was established that considers the main characteristics of the hybrid cyclic steam technology with solvents enhanced with nanomaterials (HYB-SEN), the reservoir, and some operational variables. The main objective of this procedure is to evaluate the oil production response of the catalysis of aquathermolysis reactions of asphaltenes. Also, this methodology includes the development of the kinetic model based on the thermogravimetric analysis performed on nanoparticles adsorbed by asphaltenes and Friedman's isoconversional kinetic method. The latter allowed for determining the activation energy, pre-exponential factor, and reaction order, which are inputs to numerical simulation. On the other hand, fluid property modeling was useful for integrating experimental tests such as simulated distillation, compositional analysis, properties of crude oil resulting from the aquathermolysis reaction, and the solvent used in the process (Naphtha).

The lack of information on how to represent catalytic phenomena by numerical simulation due to the presence of nanomaterials represents a great challenge to evaluating new hybrid technologies. This innovative methodological approach allows integrating the experimental results into the numerical simulation. It represents physical and chemical phenomena that occur during the process to improve the understanding of the impact of using HYB-SEN for CCS.
How Fluids Performance Ratio Analysis of ICD/AICV can be used to Analyze Oil Production, Unwanted Water and Gas Breakthrough in Carbonate or Sandstone Reservoirs
Authors: Ismail I. Mohd , Bjerke A. , Mathiesen V.
Published: June 2023

Enhanced oil recovery technique for carbonate or sandstone reservoirs using inflow control technology are often affected by undesired production of water and gas. Limited density and viscosity differences between oil, water and gas is often a challenge for most autonomous and passive inflow control technology due to limited fluids performance ratio between oil, water and gas when breakthrough happen. The fluid performance ratio describes how the ICD (Inflow Control Device) and AICD (Autonomous Inflow Control Device) preferably choke the unwanted fluid (water/gas) compared with oil.

Different ICD/AICD are utilizing both density and viscosity that effect the flow behavior difference in the valve to differentiate the pressure drop for oil, water, and gas. Different designs have been tested in single phase and multiphase full-scale flow loop testing that replicates downhole operating conditions. In order to understand the ICD/AICD behavior in reservoir environments for the duration life of the well, a wellbore model where the effect of fluids performance ratio is included. The model also includes the effect of mobility ratio and how this affects the importance of the fluid performance ratio.

Well completion has a critical role to optimize the well performance and enhanced oil recovery. In today’s engineer toolbox, a wide variety of inflow control technology completion options are available including various ICD and AICD. A new methodology and workflow have been developed to compared different type of inflow control technology completion to understand the capability to reduce unwanted water and gas production without needing detailed information about rock property variation along the wellbore in the reservoir. These methods are based on laboratory flow performance data from each device and will compare various downhole inflow control tools based on their fluid phase performance ratio to produce oil, choke water and/or gas and express the fluid preference by ratio in percentage.

Experimental flow loop results illustrate a significant different in fluids performance ratio of conventional ICD and AICV. AICD with dynamic flow area are choking water breakthrough more effectively, resulting in better sweep along the wellbore section that were not previously being produced. By limiting the water and gas production operators are therefore able to apply higher drawdown to increase oil recovery significantly. This improves the economics of thin-oil rim development and benefits of reduced environmental impact per oil produced due to less un-needed water and gas being produced to surface.
Innovative Hyperbolic Cutting Structure Brings Step Change in Drilling Efficiency Onshore Mexico
Authors: Rosique P. , Anguiano S. , Tocantins J. P. , Ross J. , Luna O.
Published: June 2023

The discovery of field T in Mexico represented the largest such find in a generation. Hence, drilling activity has been focused primarily on economically viable ways to develop these reserves. The reservoir poses several drilling challenges, such as lack of drill bit cutting structure, durability, and aggressiveness leading to unwanted bottomhole assembly trips. These challenges lead to increased well construction costs. Accordingly, an application-specific bit design needed to be developed to optimize drilling efficiency in this section. This complex drilling scenario demanded a comprehensive rock characterization study to accurately diagnose the root causes for the low drilling efficiency. To determine the environmental factors that influence bit performance, a detailed formation mapping analysis was conducted using an engineering program for rock strength identification from offset wells. This information was then used to calibrate the digital formation file inside the integrated dynamic design and analysis software, capable of reproducing actual drilling conditions. The virtual model was used to develop a specific drill bit design equipped with cutting edge 3D-cutter, optimizing performance well beyond conventional fixed and flat cutters.Results from the well D2 indicate that this innovative technology yielded superior overall drilling performance compared to best offsets and has become the new benchmark for this application in Mexico. The comprehensive planning and detailed engineering analysis led to outstanding operational execution, setting new standards for drilling performance, reducing nonproductive time drastically and therefore minimizing CO2 emissions. The customized bit design drilled the longest 10 ⅝-in run in the field. This unprecedent performance led to 29% improvement in rate of penetration when compared to conventional Polycrystalline Diamond Compact (PDC) drill bit models, reducing rig time by 5.7 days exceeding customer expectations. The learning framework was applied using post-well analysis to compare model predictions with drilling data to further refine the model and close the loop on the original calibration, paving the way for further evolution of the bit design.A successful methodology for drill bit development aimed at drilling efficiency improvement was applied using a new cutting element (hyperbolic diamond element) and novel design concepts that replaced the traditional trial-and-error methods. Testing each new design feature virtually and running parameter sensitivity analyses to ensure a wide margin of applicability, the task was made much easier by the development of a calibrated virtual formation model in a fully traceable and replicable process.
A Game-Changing Strategy to Increase the Production Tubing Run Life in a Highly Carbon-Dioxide Corrosive Environment: Shushufindi-Aguarico Fields Case Study
Authors: Romero C. , Estevez D. , Espinosa C. , Freire C. , Sierra M. C. , Aguilar L. , Rodriguez R. , Sepulveda W. , Somale J.
Published: June 2023

Since the beginning of production in Shushufindi Field, Ecuador, one of the main reasons for well intervention has been issues with the production tubing integrity. More than 30% of production tubing failures were related to corrosion in the tubing, generating additional operational expenditures and production losses. Our strategy to increase the production tubing run life in the field is presented.

In 2020, an incremental increase in field production was also accompanied by an increase in production tubing failures. Based on failure analysis that included laboratory tests, information analysis, run-life history, and simulations to predict the corrosion velocity, it was possible to identify the critical wells and to migrate the tubing grade from a L80Cr1 to a grade with 3% chromium (Cr) and maintain the use of an internal flush connection.

Before 2018, the common material used for the tubing in Shushufindi was carbon steel API N80.Q and the connection was API EU. Since November 2017 the failure index started to increase, leading to the massification of the grade L80 with 1% Cr content and an internal flush premium connection.

In 2020, the total production volume losses attributable to production tubing problems were 8%, and the average run life of wells that failed because of production tubing integrity was less than 400 days, compared to electric submersible pump (ESP) failures.

With the massive implementation of 1% Cr steel grade in 2018 and an internal flush premium connection in the tubing, the failure index was reduced from 0.33 in July 2019 to 0.14 in January 2021. However, the use of reused pipe and the strategy to increase production in the field by commingling formations and upsizing the pumps, created a more demanding condition, and induced new tubing failures.

With these new operating conditions, a strategy to mitigate early failures was to install tubing with 3% Cr content in seven critical wells. By now the tubing run life had been doubled in two wells and overlapped the previous run life in four wells.

Using a 3% Cr-grade tubing has helped to reduce the interventions by three times, and production losses have been reduced by 72,000 bbl. An opportunity to reuse pipe was identified when the tubing was recovered in perfect condition in a pullout caused by an ESP failure after 200 days. Currently (February 2023) the failure index due to communication tubing casing is 0.06.