bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling Dispersed Chemical Droplets Injection in the Gas Stream for EOR Applications
Authors: Valencia Juan D. , Mejía Juan M. , Ocampo Alonso , Restrepo Alejandro 
Published: September 2019

Abstract
This paper address the numerical simulation of the chemically enhanced gas injection technology (ChEGas-EOR) at core and reservoir scales. In this technique, a liquid chemical solution, having engineered properties, is sprayed along with the gas stream. The mist travels through the wellbore and further introduced in the reservoir. Previous lab tests, pilot studies in light & intermediate oil reservoirs indicate that the application of CheGas-EOR allows for a reduction in operational costs, increases the chemical penetration radii and decreases the retention rate in the rock. However, the associated uncertainty is still too high to develop this process on a productive scale. In this work we use a developed phenomenological model to build a tool that assist in design and evaluation of Chemical Gas EOR operations aiming to reduce the uncertainties and optimize oil recovery.
We developed a mathematical model, based on the most important transport and surface phenomena. Non-equilibrium mass transfer between phases during the interception of the chemical solution droplets with the liquid phases. Active chemical concentration in miscible liquid phases is much lower than liquid-based chemical injection opperations. As a consequence, dissolution and adsorption rate of active chemicals with reservoir rocks are slow. The model is base on the extended black-oil model formulation coupled to local mass balance equations of active chemicals. Non-equilibrium mass transfer processes are represented with interception, dissolution and a first order kinetic sorption models.
The model was adjusted and then validated using experimental data from core-.floodint tests. Good agreement of the simulations results with experimental observations were obtained. The model can predict the relevant behavior of the disperse chemical injection in the gas phase in porous media. Also, well injections simulations at reservoir scale using the matched parameters from laboratory, reproduced pilot field results. Simulation experiments predict that the CheGasEOR process can increased substantially the oil recovery factor.
For the first time, a model for disperse chemical injection for EOR applications is developed and validated at core and reservoir scale. The simulation model allows the evaluation of this technology at different scales. Therefore, it is possible to use it to optimize operating conditions and perform sensitivity analysis for field applications.
Giant Field Development Optimisation with the Consideration of Regional Voidage Replacement Ratio
Authors: BaniHammad Najoud Hassan , Kedia Rachit , AlSabeai Jawaher 
Published: September 2019

Abstract
Net present value (NPV) and voidage replacement ratio (VRR) are the key drivers to define an optimal reservoir development strategy that maximizes returns while maintaining reservoir health. In the subsurface context, maximizing NPV consists of optimizing the well locations. Voidage replacement ratio (VRR), which is defined as the ratio between the volume of injected fluid and the volume of produced fluid, measures the rate of change in reservoir energy. Conventionally, operators try to maintain a VRR close to one during the whole field life. Typically a single value of VRR is used as a metric to represent the whole reservoir. However, this approach does not capture the lateral variation in pressure seen in giant fields.
This paper focuses on a more suitable method for determining the VRR for each user-defined pressure region using reservoir simulation. This method is used to plan the location of future wells during the long term development plan and maximize NPV and recovery. Two scenarios of well location will be examined. The first scenario consists of optimizing well location using a single VRR metric for the whole field. The second scenario uses the VRR from each pressure region to decide on the optimum number of wells per region.
This latter approach is shown to give better results in planning well location for future field development and is consistent with the reservoir pressure distribution across the field.
Perched Water - Identification and Production Behavior In A Real Case
Authors: Macaluso Daniela , Colombi Nazzarena , Castelnuovo Luca , Calderoni Mirko , Prevosti Paolo Battista 
Published: September 2019

Abstract
Unexpected water accumulation (called perched water) can be present inside hydrocarbon bearing reservoirs. In case of limited or poor geophysical data, the prediction of this accumulation may be difficult.
In this paper, a real case is used to show how the presence of perched water was initially supposed and then verified through production data analysis.
During the development campaign of a deep water reservoir in West Africa, a water injector well found an unexpected shallower water table. To understand the nature of this water, the gas while drilling data of two oil producer drilled in the same area of the water injector were analysed. Based on this analysis the last meters of the open hole section of both oil producers were in water. The integration of gas while drilling data, stratigraphy, sedimentology and structural settings knowledge of the area suggested that this water was locally trapped during oil migration, most likely due to the presence of a structural barrier.
The two oil producer wells, located in the supposed perched water area, were successfully started-up. The behavior of both wells was daily monitored to understand and confirm the nature of perched water phenomenon. From day one, the two wells showed water production. After few weeks, the water cut of one well clearly started to reduce. For the other well, the water cut behavior was constant and only after one year of production the declining trend was appreciated. The observed declining trend of water production was the final confirmation that aquifer in this sector of the field is isolated and with limited extension. The water cut trend was also captured in the 3D dynamic reservoir model. In addition, tracers were implemented in the model to identify different water production sources (injected or perched) and to forecast their evolution during the field life.
The literature on perched water is quite limited and usually this kind of phenomenon is detected and described only on the geological side, but the production behavior of this water is rarely observed. This case study is integrating the geological and geophysical knowledge of the field with production data analysis to understand perched water behavior and can be considered a reference for other similar situation.
Maximising the Use of Horizontal Well Data in the Structural Framework of the Reservoir Modelling Workflow: A Case Study of a Middle East Carbonate Reservoir
Authors: Contreras Perez David Rafael , Al Zaabi Ruqaya Abdulla , Viratno Bernato , Sellar Christopher , Susanto Maria Indriaty 
Published: September 2019

Abstract
This paper summarizes an efficient workflow for building a reliable static model reference case by improving the accuracy of well placement in a hydrocarbon bearing structure. This is beneficial in optimising upcoming well target position and trajectory planning as well as during the dynamic history matching process. In a non-operated venture, the ability to generate an up-to-date static model that maintains pace with operations, provides valuable insight to advise the operator on the upcoming drilling plan and continuously supports the dynamic model for reserves booking, is highly sought after.
The systematic approach described in this paper is applied to a geo-model from a Middle East carbonate reservoir consisting of over 50 wells with good quality PSDM seismic data. The workflow presented begins with seismic mapping, utilizing volume-based modelling techniques, followed by structural element correction using borehole images (e.g. structural formation dip and true stratigraphic thickness estimate) and finally introduces alternative control points, which enable drilled wellbore trajectories to be structurally anchored, based on layer thicknesses and structural trends within the target reservoir.
Using this approach it is possible to generate a consistent structural model that honours geological markers, measured dip ranges and structural trends seen from seismic data and image logs. During the process one learns more about data quality (e.g. scale of data resolution and depth of investigation), associated with specific fields and carbonate reservoirs through the interaction between geological, geophysical and petrophysical disciplines and ensures their correct use. Data are used to improve the raw interpreted seismic horizons by calibrating mapped thickness distribution against the well tops. 2D visualizations are generated on a well-by-well basis, including map views, curtain sections (along each horizontal well), composite cross-sections and 3D visualizations to show inter-well relationships within different geological layers. As a result the well is placed in the correct structural position. Correct well placement, especially of highly deviated/horizontal wells, provides more accurate identification of reservoir sweet spots, leading to improved well target position and trajectory planning for upcoming wells, and a robust baseline to achieve production/well test history match during the dynamic modelling process.
Digital Pore Space Study of a Middle-Eastern Carbonate Rock Sample
Authors: Tallec Gwenole 
Published: September 2019

Abstract

Objectives/Scope
While Image processing is still an area of research, standard workflows have emerged and are routinely used in Oil&Gas companies.
However, while hardware capabilities have increased consequently, allowing large samples to be scanned with a high fidelity, permeability simulations are still limited to small samples unless having access to HPC. Direct simulations are known to be more flexible in terms of type of rocks, but limited in terms of sample size, while Pore Network Model based allow much larger sample sizes but less rock types.

Methods
In this study, we will focus on the pore space analysis of a middle-eastern carbonate sample. The rock sample is 7.5 cm tall and has a diameter of 3.8 cm.
It has been acquired at 3 different resolution: a microCT scan at 16μm, a microCT scan of a 10 mm of diameter subsample at 5 μm, and a 10 mm of diameter SEM section at 2μm.
This study will propose a methodology to mix the different scales in order to get an accurate pore space analysis of the largest possible sample size.

Results
As micro porous regions are visible at every scale, bringing uncertainty to the segmentation step, the first part of our analysis will consist of determining the most accurate pore space at the three different resolutions. We will rely on image registration (2D to 3D and 3D to 3D) and image based upscaling methods, further validated by simulation results.
Given the large numerical size of the samples, specific workflows involving large data 3D visualization and processing will be presented.
Then, different measures will be conducted: porosity and connected porosity, absolute permeability with three different methods (Lattice Boltzmann, Finite Volume, Pore Network Modeling), relative permeability curves using a Pore Network Model simulator. A new pore network model generation applicable to highly concave pore spaces such as carbonates ones will also be introduced.

Novel
A scalable method using automation will be presented, so that repeating the simulations on different samples of different space origins and size is easy.
We will expose the results and limits of every method and will determine which size is bringing a convergence of the results. We will especially look at the convergence of direct based simulations and pore network model based ones, such that expanding the size prior to Pore Network Model generation can be reliable.
In addition to the benchmark of the different simulation methods and their associated limits, the results will help us determining the representative elementary volume at different resolutions and the associated uncertainty depending on whether sub-resolution acquisitions are available or not.
Grid and Fluid Independent Description for Multilateral Horizontal Well in Dynamic Simulation
Authors: Bogachev Kirill Yu. , Erofeev Vladislav D. , Piskovskiy Evgeny V. 
Published: September 2019

Abstract
The method for modeling of a multilateral well design that is completely independent on the simulation grid and fluid properties is proposed. The method takes into account friction in the lateral branches and crossflow between them. Well parameters, such as trajectory, perforation intervals, roughness and diameter, are directly used to calculate pressure distribution along the wellbore at the current fluid composition and tubing head pressure (THP).
Well connections with grid blocks in a finite volume approximation for dynamic model should be created. The automatic creation of the well connections during dynamic simulation based on specified well trajectory and completion intervals is proposed. The connection factor is suggested to be calculated based on length of completion intersection with the block, trajectory direction and rock properties during the run time. To calculate pressure drop on well track intervals between connections and the well track intervals between top completion and tubing head the well-known correlations are utilized. The correlations are used for the current fluid composition in the wellbore in each connection using information for well trajectory, roughness and diameter.
Such an approach makes it possible to get rid of the use of the tabulated bottomhole pressure (BHP) as a function of tubing head pressure for a number of phase compositions. Such traditional use of phase compositions gives a non-physical response in compositional models, where the component composition of the product varies significantly throughout the life of the field. Usage of real coordinates (x, y, z) for setting well trajectory and perforation intervals, instead of the traditional grid block numbers (i, j, k), allows to calculate layer intersection, connection factors and pressure distribution along wellbore with arbitrary changes in the dynamic model grid, for example, when introducing local grid refinement or dynamic grid and rock properties variation used to describe hydraulic fracturing.
The proposed method is successfully used for modeling of a multilateral well design in dynamic simulation. The results of such dynamic simulation are consistent with the real samples from reservoir.
Machine Learning for 3D Image Recognition to Determine Porosity and Lithology of Heterogeneous Carbonate Rock
Authors: Al-Farisi Omar , Zhang Hongtao , Raza Aikifa , Ozzane Djamel , Sassi Mohamed , Zhang TieJun 
Published: September 2019

Abstract
Automated image processing algorithms can improve the quality and speed of classifying the morphology of heterogeneous carbonate rock. Several commercial products have worked to produce petrophysical properties from 2D images and with less extent from 3D images, relying on image processing and flow simulation. Images are mainly micro-computed tomography (μCT), optical images of thin-section, or magnetic resonance images (MRI). However, most of the successful work is from the homogeneous and clastic rocks. In this work, we have demonstrated a Machine Learning assisted Image Recognition (MLIR) approach to determine the porosity and lithology of heterogeneous carbonate rock by analyzing 3D images form μCT and MRI. Our research method consists of two parts: experimental and MLIR. Experimentally, we measured porosity of rock core plug with three different ways: (i) weight difference of dry and saturated rock, (ii) NMR T2 relaxation of saturated rock, and (iii) helium gas injection of rock after cleaning and drying.
We performed MLIR on 3D μCT and MRI images using random forest machine-learning algorithm. Petrophysicist provided a set of training data with classes (i.e., limestone, pyrite, and pore) as expert knowledge of μCT Image intensity correspondence to petrophysical properties. MLIR performed, alone, each task for identifying different lithology types and porosity. Determined volumes have been checked and confirmed with three different experimental datasets. The measured porosity, from three experiment-based approaches, is very close. Similarly, the MLR measured porosity produced excellent results comparatively with three experimental measurements, with an accuracy of 97.1% on the training set and 94.4% on blind test prediction.
Evaluation of CO2-EOR Project for an Oil Field in Abu Dhabi, UAE Based on Industry Best Practices
Authors: Chirkov Maxim , Coughlin Matthew Kent , Ponte Pineda Wuilmer Jose 
Published: September 2019

Abstract
Enhanced oil recovery ("EOR") by means of CO2 injection has become a globally-used method of increasing oil recovery. Interest in the UAE has increased in recent years due to the proven effectiveness of the process, and due also to government plans to initiate a world-class CO2 capture campaign.
EOR by means of CO2 injection is associated with many challenges. The majority of EOR projects are conducted in onshore fields since offshore EOR experience is limited by technical and operational challenges, as well as by higher economic hurdles. A larger resource base is required to justify an offshore EOR project than a project that is located onshore. Apart from that, the decision to embark on a CO2 injection project is often complicated by the lack of multidisciplinary integration. Uncertainty analysis should be included in the evaluation since it is critical to understanding pilot objectives, identifying model limitations, proper scaling of results from the pilot area to the field, and managing expectations. The economics of the proposed project are strongly dependent on proper baseline definition – possible only by means of advanced methods of reservoir characterization – and by state-of-the-art methods of dynamic reservoir simulation using a fully-compositional model and robust equations of state to characterize the process physics.
The oilfield discussed in this paper is a digital multi-reservoir field being developed by horizontal and highly-deviated wells equipped by inflow control devices (ICD). Primary depletion will be augmented by reservoir-specific water injection and hydrocarbon gas injection. Field characterization is being done based on data from comprehensive open- and cased-hole log suites, seismic data, MDT runs, PTA, and an array of SCAL and PVT tests necessary to fully describe the process physics.
The purpose of this paper is to describe the workflow and methods used to design, and estimate the efficiency of a CO2 injection project for a carbonate reservoir complex in the offshore area of the UAE. Recommendations for pilot project and surveillance program designs based on best practices and lessons learned from prior projects, developed to overcome the challenges described above, are discussed.
Efficient Optimization of Field Management Strategies in Reservoir Simulation
Authors: Ahmed Elfeel Mohamed , Ali Samad , Giddins Marie Ann 
Published: September 2019

Abstract
Standard approaches to optimization under uncertainty in reservoir simulation require use of multiple realizations, with variable parameters representing operational constraints and actions as well as uncertain scenarios. We will show how appropriate use of local optimization within the simulation model, using customized logic for field management strategies, can bring improved workflow flexibility and efficiency, by reducing the effort needed for uncertainty iterations.
To achieve meaningful forecasts for an ensemble of uncertain scenarios, it is important to distinguish between different types of decision. Investment decisions, such as facilities sizing, depend on global unknowns and must be optimized for the complete ensemble. Operational actions, such as closing a valve, can be optimized instantaneously for individual scenarios, using measurable information, although subject to constraints determined at a global level. In this study, we implement local optimization procedures within simulation cases, combining customized objective criteria to rank reactive or proactive actions, with the ability to query reservoir flow entities at appropriate frequencies.
The methods presented in the paper can be used for reactive response modeling for smart downhole control; optimization of ESP/PCP pump performance; and implementation of production plans subject to defined downstream limits. For selected cases, we compare the advantages and disadvantages of the local optimization approach with standardized "big-loop" uncertainty workflows. The methodology can significantly reduce optimization costs, particularly for high-frequency actions, achieving similar objective function values in a fraction of the time needed for post-processing optimizers. Use of tailored scripting provides the capability to modernize the logic framework for field management decisions, with realistic representation of smart field equipment and flow entities at any level of complexity.
Use of efficient workflows as described in this paper can reduce the cost of multiple realization studies significantly, or enable engineers to consider a wider range of possible scenarios, for deeper understanding and better risk mitigation.
Transition Zone Characterization for Simulation Models of Gas Bearing Carbonate Reservoir
Authors: Faizova Tatiana , Butorina Mariia , Goncharov Alexey , Nekhaev Sergey 
Published: September 2019

Abstract
Nowadays demand makes gas one of the desirable hydrocarbon sources of energy. However reservoirs size and quality of new discoveries or old preserved one are poor. This fact set the task for simulation of accurate prediction in order to evaluate economic reasonability of production.
This study concerns the question of changes gas production profile at the gas-bearing carbonate formation due to presence of transition zone. The different ways of simulation models initialization are implemented. Then the changes of the total output are compared and analyzed. In addition the advantages of initialization by means of J-function over capillary pressure curve assignment for the carbonate formation with highly heterogeneous flowing properties are explained. All results are coupled to vertical flow performance of wells which were matched at the tests.
The study shows that transition zone should be taken into account in simulation modeling of the gas-bearing no less than for the oil-bearing formations. Also the total gas production compared with and without the transition zone implementation due to its production is sensitive to presence any liquid. Accurate J-function matching at the core data provide better result for water breakthrough thus the performance of wells and finally the total production profile. The vertical flow performance curves adjustment and subsequent use for the simulation is the additional need which considered because in the case of the surface equipment restriction, such as the tubing head pressure limits, the pressure loss in the presence of gas and water mixture could be huge which cause early shutdown of the wells.
It is shown that gas bearing is not the reason to neglect the importance of the capillary force and the presence of the transition zone which has essential impact on the total formation performance.