Characterization of marble weathering through pore structure quantitative analysis

Y Stone weathering is strongly controlled by the intrinsic properties of the stone and by its use. Previous studies demonstrate that the response to natural or artificial ageing processes of the rocks seems to be strongly influenced by the pore structure of the stone. A better understanding of this phenomenon is provided by the study and characterization of porosity and of the pore structure at different degrees of alteration. The analysis of the evolution of the decay leads to the evaluation of the durability of marble in facades, and more generally in buildings, as well as for the protection and recovery of artistic and architectural heritage.In this paper, we apply a methodology for the geometrical characterization of the pore structure to quantify alteration induced by natural weathering on marble slabs. The approach is based on the application of a path-finding algorithm to 2D binary images representative of thin sections of marble at different degrees of alteration. Through the identification of the paths within the porous domain, the methodology allows the characterization of the pore structure in terms of pore radius distribution along the identified paths. Analysis of the results demonstrate a good agreement between the degree of alteration of the pore structure and the corresponding variation of the physical and mechanical properties of the rock samples under investigation

Harmonic Pulse Testing for Well Monitoring: application to a fractured geothermal reservoir

Harmonic Pulse Testing (HPT) has been developed as a type of well testing applicable during ongoing field operations because a pulsed signal is superimposed on background pressure trend. Its purpose is to determine well and formation parameters such as wellbore storage, skin, permeability and boundaries within the investigated volume. Compared to conventional well testing, HPT requires more time to investigate the same reservoir volume. The advantage is that it does not require the interruption of well and reservoir injection/production before and/or during the test because it allows the extraction of an interpretable periodic signal from measured pressure potentially affected by interference. This makes it an ideal monitoring tool. Interpretation is streamlined through diagnostic plots mimicking conventional well test interpretation methods. To this end, analytical solutions in the frequency domain are available. The methodology was applied to monitor stimulation operations performed at an Enhanced Geothermal System (EGS) site in Pohang, Korea. The activities were divided into two steps: first a preliminary sequence of tests, injection/fall‐off and two HPTs, characterized by low injection rates and dedicated to estimate permeability prior to stimulation operations; then stimulation sequence characterized by higher injection rate. During the stimulation operations other HPTs were performed to monitor formation properties behavior. The interpretation of HPT data through the derivative approach implemented in the frequency domain provided reliable results in agreement with the injection test. Moreover, it provided an estimation of hydraulic properties without cessation of stimulation operations, thus confirming the effectiveness of HPT application for monitoring purposes

Data for: Pulse Testing For Monitoring the Thermal Front in Aquifer Thermal Energy Storage

These are synthetic pressure and rate data, generated by commercial software, that simulate the pressure response of a Aquifer Thermal Energy Storage (ATES) doublet system to Harmonic Pulse Test. HPTs were simulated at significant stages of storage cycles in order to verify the capability of the test in monitoring the heat front. More in details, the thermal front was monitored after the 5thsummer of storage (4 complete storage cycles) and after the subsequent winter and again after the 15thsummer of storage (14 complete storage cycles). Moreover, synthetic pressure and rate data, generated by analytical model in time (radial composite assumption) and numerical model accounting for thermal exchange, to simulate the pressure response of a doublet system to Harmonic Pulse Test are also provided. HPTs were simulated at different stages of water injection in order to verify the capability of the test in monitoring the heat front. More in details, the thermal front was monitored after 1 month and after 6 months

Data for: Pulse Testing For Monitoring the Thermal Front in Aquifer Thermal Energy Storage

These are synthetic pressure and rate data, generated by commercial software, that simulate the pressure response of a Aquifer Thermal Energy Storage (ATES) doublet system to Harmonic Pulse Test. HPTs were simulated at significant stages of storage cycles in order to verify the capability of the test in monitoring the heat front. More in details, the thermal front was monitored after the 5thsummer of storage (4 complete storage cycles) and after the subsequent winter and again after the 15thsummer of storage (14 complete storage cycles)

Data for: Pulse Testing For Monitoring the Thermal Front in Aquifer Thermal Energy Storage

These are synthetic pressure and rate data, generated by commercial software, that simulate the pressure response of a Aquifer Thermal Energy Storage (ATES) doublet system to Harmonic Pulse Test. HPTs were simulated at significant stages of storage cycles in order to verify the capability of the test in monitoring the heat front. More in details, the thermal front was monitored after the 5thsummer of storage (4 complete storage cycles) and after the subsequent winter and again after the 15thsummer of storage (14 complete storage cycles). Moreover, synthetic pressure and rate data, generated by analytical model in time (radial composite assumption) and numerical model accounting for thermal exchange, to simulate the pressure response of a doublet system to Harmonic Pulse Test are also provided. HPTs were simulated at different stages of water injection in order to verify the capability of the test in monitoring the heat front. More in details, the thermal front was monitored after 1 month and after 6 months

A New 3-D Numerical Model to Effectively Simulate Injection Test

Paper of SPE Europec/EAGE 200

An Effective Criterion to Prevent Injection Test Numerical Simulation from Spurious Oscillations

Injection/fall-off tests are one of the most promising alternatives to the conventional production/build-up sequence because they eliminate surface emissions and can significantly reduce testing costs. This kind of test is characterized by the presence of two mobile phases, the fluid originally in place (hydrocarbon) and the injected fluid (Diesel, brine or nitrogen). The conventional analytical approach used to describe the transient pressure behavior is no longer suitable due to the variations in fluid saturations during the test. Although applicable in theory, the analytical approach often implies excessive simplifications of the real system behavior, such as piston-like displacement. Thus only numerical simulations can thoroughly describe the phenomena occurring during the injection process. However, the pressure and pressure derivative response calculated numerically often shows non-physical oscillations during the radial flow phase, when the pressure derivative is expected to be horizontal. It was found that these spurious oscillations arise in convection-dominated problems and are associated with sharp saturation fronts. In this paper, an effective methodology, based on an adaptive time-step calculation, is presented so as to avoid pressure oscillations. The proposed time-step selection is both computationally efficient and suitable to capture the physics of the system

Data automation for image logs texture analysis: supervised methodology and case studies

A new methodology for the recognition of geological and lithological textures in borehole image logs has been developed and tested. The workflow consists of a features-extraction step, to provide the initial segmentation, inspired by the multi-channel filtering theory, and a classification step, to provide the texture map. The workflow is simple and parametric, making it suitable for automatic interpretation of a wide range of geological images. The goal of this work was the automatic recognition of textural facies in high-resolution microresistivity image logs, using information derived from core interpretation to improve the quality of the classification in intervals biased by poor log quality

Improved subsurface property prediction in the Netherlands by integrating stratigraphic forward modelling

Classic geological reservoir characterisation relies on interpolation of high resolution well data with (at best) low resolution seismic derived data. In order to fill the data gap (e.g. in labyrinthine type fluvial deposits) we present a methodology to integrate basin scale information in reservoir scale static models by calibrating output from a Stratigraphic Forward Model (SFM). This project showcases the applicability of the integrated workflow to improve facies and property prediction at different scales. By calibrating the parameterized data from the SFM to independent constraints such as thicknesses from seismic interpretations and well logs the model greatly improve property prediction. Previous studies showed the application to synthetic datasets, this study aims to apply the methodology to the Holocene Rhine-Meuse fluvial deposits in the shallow subsurface of the Netherlands. The extraordinary level of detail in the model of these deposits and the parameterized fluvial sedimentation routine in the SFM used provide an ideal test case for the workflow proposed. The ultimate application of the workflow is intended to improve the geological and property models at greater depth where data coverage is limited. © 2016, European Association of Geoscientists and Engineers, EAGE. All rights reserved