Advanced Modeling Capability to Enhance Near-Wellbore and Far-Field Bridging in Acid Fracturing Field Treatments

2021 ◽  
Author(s):  
Abdul Muqtadir Khan ◽  
Denis Emelyanov ◽  
Rostislav Romanovskii ◽  
Olga Nevvonen
Keyword(s):  
High Resolution ◽  
Fluid Transport ◽  
Field Studies ◽  
Particulate Material ◽  
Injection Rate ◽  
Far Field ◽  
Field Scale ◽  
Fracture Width ◽  
Acid Fracturing ◽  
Modeling Approach

Abstract Different applications of fracture bridging and diversion are used regularly in carbonate acid fracturing without an in-depth understanding of the physical phenomena that dominate the processes involved in the bridging and diversion process. The extension of modeling capabilities in conjunction with yard-scale and field-scale experiences will increase our understanding of these processes. A robust multimodal diversion pill and polylactic acid fiber-laden viscous acid were utilized for near-wellbore and far-field bridging, respectively. Numerous field treatments demonstrated the uncertainty of achieving effective diversion. An existing multiphysics model was extended to develop functionalities to model diversions at different scale. Extensive laboratory testing was conducted to understand the scale of bridging and diversion mechanisms. Finally, a bridging yard test was designed, and field case studies were used to integrate all the branches. Field cases showed a diversion pressure up to 4,000 psi depending on perforation strategy, pill volume, and pill seating rate. Correlations showed the interdependence of multiple parameters in diversion processes. The field studies motivated modeling capabilities to simulate the critical diversion processes at high resolution and quality. The model simulates diverting agents that reduce leakoff in the fracture area and their effects on fracture geometry. The approach considers the acid reaction kinetics coupled with geomechanics and fluid transport. Different diverting agent concentrations required for bridging can be modeled effectively. A yard test was designed to confirm the integrity of the pill material through completion valves (minimum inside diameter 9.5 mm) and analyzed with high-resolution imaging. All the theoretical, mathematical, and numerical findings from modeling were integrated with laboratory- and yard-scale experimentation results to develop and validate near-wellbore and far-field diversion modeling. Analytical correlations were formulated from injection rate, particulate material concentration, pill volumes, fracture width, etc., to incorporate and validate the model. This study enhances understanding of the different diversion mechanisms from high-fidelity theoretical modeling approach integrated with a practical experimental view at laboratory and field scale. Current comprehensive research has significant potential to make the modeling approach a reliable method to develop tight carbonate formations around the globe.

Possible applications of fraunhofer holography in high resolution electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 222-223 ◽  
Author(s):  
N. Bonnet ◽  
M. Troyon ◽  
P. Gallion
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transfer Function ◽  
Radiation Damage ◽  
High Resolution Electron Microscopy ◽  
Far Field ◽  
Field Region ◽  
Crystalline Materials ◽  
Resolution Electron ◽  
The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

Identification of amines in wintertime ambient particulate material using high resolution aerosol mass spectrometry

2018 ◽  
Vol 180 ◽  
pp. 173-183 ◽  
Author(s):  
Courtney L.H. Bottenus ◽  
Paola Massoli ◽  
Donna Sueper ◽  
Manjula R. Canagaratna ◽  
Graham VanderSchelden ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Particulate Material ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry

scholarly journals Randomized apertures: high resolution imaging in far field: erratum

2017 ◽  
Vol 25 (17) ◽  
pp. 20952
Author(s):  
Xiaopeng Peng ◽  
Garreth J. Ruane ◽  
Marco B. Quadrelli ◽  
Grover A. Swartzlander
Keyword(s):  
High Resolution ◽  
Far Field ◽  
High Resolution Imaging ◽  
Resolution Imaging

scholarly journals THEORETICAL MODEL FOR CALCULATION OF THE EFFECTIVE SHEAR VISCOSITY OF A PSEUDO-PLASTIC MATERIAL IN A FRACTURE

2016 ◽  
pp. 77-80
Author(s):  
S. V. Ovchinnikova ◽  
G. H. Ali
Keyword(s):  
Theoretical Model ◽  
Shear Viscosity ◽  
Effective Viscosity ◽  
Plastic Material ◽  
Injection Rate ◽  
Viscoelastic Liquid ◽  
Oil Fields ◽  
Fracture Width ◽  
Gel Injection ◽  
Artificial Fracture

The ultimate goal of this work was to develop a method which can be used in mature oil fields to determine the effective viscosity of the granulated gel (PPG) used for plugging the anthropogenic fractures (after FHF). Using the laboratory fracture model the values of constants (apparent constant consistency, ka, and the apparent index of pseudoplasticity, na) were obtained for the equation of viscoelastic liquid. The same constants were used in the derived equation for pressure gradient along the artificial fracture. The gel effective viscosity was calculated based on the equation of the gel motion along the fracture. This equation enables to calculate the effective viscosity of PPG for each size the granulated gel fraction depending on the fracture width and the gel injection rate.

scholarly journals Forecasting maize yield at field scale based on high-resolution satellite imagery

2018 ◽  
Vol 171 ◽  
pp. 179-192 ◽  
Author(s):  
Rai A. Schwalbert ◽  
Telmo J.C. Amado ◽  
Luciana Nieto ◽  
Sebastian Varela ◽  
Geomar M. Corassa ◽  
...  
Keyword(s):  
High Resolution ◽  
Satellite Imagery ◽  
Maize Yield ◽  
Field Scale ◽  
High Resolution Satellite Imagery

scholarly journals Predicting Wheat Yield at the Field Scale by Combining High-Resolution Sentinel-2 Satellite Imagery and Crop Modelling

2020 ◽  
Vol 12 (6) ◽  
pp. 1024 ◽  
Author(s):  
Yan Zhao ◽  
Andries B Potgieter ◽  
Miao Zhang ◽  
Bingfang Wu ◽  
Graeme L Hammer
Keyword(s):  
High Resolution ◽  
Crop Production ◽  
Vegetation Index ◽  
Wheat Yield ◽  
Crop Model ◽  
Stress Index ◽  
Yield Prediction ◽  
Field Scale ◽  
Crop Water Stress Index ◽  
Sentinel 2

Accurate prediction of crop yield at the field scale is critical to addressing crop production challenges and reducing the impacts of climate variability and change. Recently released Sentinel-2 (S2) satellite data with a return cycle of five days and a high resolution at 13 spectral bands allows close observation of crop phenology and crop physiological attributes at field scale during crop growth. Here, we test the potential for indices derived from S2 data to estimate dryland wheat yields at the field scale and the potential for enhanced predictability by incorporating a modelled crop water stress index (SI). Observations from 103 study fields over the 2016 and 2017 cropping seasons across Northeastern Australia were used. Vegetation indices derived from S2 showed moderately high accuracy in yield prediction and explained over 70% of the yield variability. Specifically, the red edge chlorophyll index (CI; chlorophyll) (R2 = 0.76, RMSE = 0.88 t/ha) and the optimized soil-adjusted vegetation index (OSAVI; structural) (R2 = 0.74, RMSE = 0.91 t/ha) showed the best correlation with field yields. Furthermore, combining the crop model-derived SI with both structural and chlorophyll indices significantly enhanced predictability. The best model with combined OSAVI, CI and SI generated a much higher correlation, with R2 = 0.91 and RMSE = 0.54 t/ha. When validating the models on an independent set of fields, this model also showed high correlation (R2 = 0.93, RMSE = 0.64 t/ha). This study demonstrates the potential of combining S2-derived indices and crop model-derived indices to construct an enhanced yield prediction model suitable for fields in diversified climate conditions.

An Integrated Experimental Method to Investigate Tool-Less Temporary-Plugging Multistage Acid Fracturing of Horizontal Well by Using Self-Degradable Diverters

SPE Journal ◽  
2020 ◽  
Vol 25 (03) ◽  
pp. 1204-1219 ◽  
Author(s):  
Lufeng Zhang ◽  
Fujian Zhou ◽  
Jianye Mou ◽  
Wei Feng ◽  
Zhun Li ◽  
...  
Keyword(s):  
Fracture Surface ◽  
Evaluation System ◽  
Horizontal Well ◽  
Single Type ◽  
Fracture Width ◽  
Acid Fracturing ◽  
Integrated Method ◽  
Tight Carbonate ◽  
Operation Cost ◽  
Insight Into

Summary Tool-less temporary-plugging multistage acid fracturing of horizontal well is a necessary technology to unlock the production potential and enable commercial productivity for tight carbonate reservoirs. However, this technique has not been investigated experimentally yet, and the plugging behavior of diverters within acid-etched fracture is still unclear. In this paper, we propose an integrated method to experimentally study tool-less multistage fracturing with diverters. First, we introduce an innovative 3D printing method to reproduce the roughness of acid-etched fracture surface and design an acid-etched fracture temporary plugging evaluation system to satisfy the requirements of temporary plugging experiments. Then, we conduct a series of plugging experiments to optimize the diverter's formula for creating a tight plugging zone within an acid-etched fracture under different fracture widths. On the basis of the description of the fracture surface, we further analyze the formation process and mechanism of temporary plugging. Finally, we further verify through laboratory experiments using a modified true tri-axial fracturing system the feasibility of using a single type of diverter and combined diverters to achieve tool-less temporary plugging staged fracturing of horizontal well. The experimental results show the following findings: (1) Pure fibers can realize temporary plugging at lower fracture width (≤2 mm). (2) To achieve temporary plugging, the diameter of particulates should not be less than half of the fracture width under the condition of larger fracture width (≥4 mm). (3) The fracture surface morphology affects the formation time of temporary plugging, but does not affect whether temporary plugging is formed or not. (4) Using a steel plate with a smooth fracture surface to conduct optimization experiments will increase the dosage of diverters, thus increasing the operation cost. (5) Pure particulates cannot achieve favorable plugging effect. This study provides an insight into multistage acid fracturing.

scholarly journals Estimating Unpropped-Fracture Conductivity and Fracture Compliance From Diagnostic Fracture-Injection Tests

SPE Journal ◽  
2018 ◽  
Vol 23 (05) ◽  
pp. 1648-1668 ◽  
Author(s):  
HanYi Wang ◽  
Mukul M. Sharma
Keyword(s):  
Earth Science ◽  
Mathematical Framework ◽  
Field Scale ◽  
Time Data ◽  
Fracture Conductivity ◽  
Reliable Technique ◽  
Fracture Width ◽  
In Situ Conditions ◽  
Fracture Closure

Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures. During the past 2 decades, the DFIT has evolved into a commonly used and reliable technique to obtain in-situ stresses, fluid-leakoff parameters, and formation permeability. The pressure-decline response across the entire duration of a DFIT reflects the process of fracture closure and reservoir-flow capacity. As such, it is possible to use these data to quantify changes in fracture conductivity as a function of stress. In this paper, we present a single, coherent mathematical framework to accomplish this. We show how each factor affects the pressure-decline response, and the effects of previously overlooked coupled mechanisms are examined and discussed. Synthetic and field-case studies are presented to illustrate the method. Most importantly, a new specialized plot (normalized system-stiffness plot) is proposed, which not only provides clear evidence of the existence of a residual fracture width as a fracture is closing during a DFIT, but also allows us to estimate fracture-compliance (or stiffness) evolution, and infer unpropped fracture conductivity using only DFIT pressure and time data alone. It is recommended that the normalized system-stiffness plot (NS plot) be used as a standard practice to complement the G-function or square-root-of-time plot and log-log plot because it provides very valuable information on fracture-closure behavior and the properties of fracture-surface roughness at a field-scale, information that cannot be obtained by any other means.

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