Swabbing-Test Interpretation Using Nonlinear Regression in San Jorge Gulf Basin

2010 ◽  
Vol 13 (04) ◽  
pp. 596-602
Author(s):  
Euver Naranjo ◽  
José Bravo ◽  
Eugenio Díaz ◽  
José Caldera
Keyword(s):  
Dynamic Properties ◽  
Test Interpretation ◽  
Transient Pressure ◽  
Individual Layer ◽  
Well Completion ◽  
Reservoir Permeability ◽  
Production Models ◽  
Routine Basis ◽  
Instantaneous Flow Rate ◽  
First Time

Summary In the San Jorge basin in southern Argentina, swabbing tests are the conventional testing technique used by YPF to evaluate production potential on those reservoirs that do not flow naturally to surface. During the well-completion phase, a swabbing device is lowered into the wellbore to test each reservoir layer individually. These wells, which produce from multilayer formations, are later completed for commingled production. Accordingly, the swabbing test represents the only opportunity to measure dynamic properties for each individual layer. So far, pressure-transient analysis of such tests has been limited to the use of conventional interpretation methods applied to the infinite-acting radial-flow (IARF) portion on those tests in which such a flow regime is observed. This can happen if a bottomhole shut-in valve is used or if the shut-in period is given a long enough time for the bottomhole pressure to reach conditions close to initial reservoir pressure. Unfortunately, both practices increase the completion cost substantially, which affects well economics strongly. As a result of this economic limitation, neither practice is applied on a routine basis, so most of the time, transient-pressure interpretation is not performed. In an attempt to obtain value from routine swabbing tests, where an IARF condition is not observed, a different method of test interpretation has been introduced. Through the computation of the instantaneous flow rate from the pressure-trend increase during the swabbing period, it is possible to use nonlinear numerical regression to make an estimation of the reservoir permeability, even if IARF is not present. With this innovative approach, YPF is constructing for the first time representative production models for each well, thereby improving reserves estimations and production forecasts.

scholarly journals Structural Transitions at Microtubule Ends Correlate with Their Dynamic Properties in Xenopus Egg Extracts

2000 ◽  
Vol 149 (4) ◽  
pp. 767-774 ◽  
Author(s):  
Isabelle Arnal ◽  
Eric Karsenti ◽  
Anthony A. Hyman
Keyword(s):  
Dynamic Instability ◽  
Dynamic Properties ◽  
Microtubule Assembly ◽  
Two Dimensional ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Xenopus Egg Extracts ◽  
First Time ◽  
The Relationship ◽  
Dynamic Populations

Microtubules are dynamically unstable polymers that interconvert stochastically between growing and shrinking states by the addition and loss of subunits from their ends. However, there is little experimental data on the relationship between microtubule end structure and the regulation of dynamic instability. To investigate this relationship, we have modulated dynamic instability in Xenopus egg extracts by adding a catastrophe-promoting factor, Op18/stathmin. Using electron cryomicroscopy, we find that microtubules in cytoplasmic extracts grow by the extension of a two- dimensional sheet of protofilaments, which later closes into a tube. Increasing the catastrophe frequency by the addition of Op18/stathmin decreases both the length and frequency of the occurrence of sheets and increases the number of frayed ends. Interestingly, we also find that more dynamic populations contain more blunt ends, suggesting that these are a metastable intermediate between shrinking and growing microtubules. Our results demonstrate for the first time that microtubule assembly in physiological conditions is a two-dimensional process, and they suggest that the two-dimensional sheets stabilize microtubules against catastrophes. We present a model in which the frequency of catastrophes is directly correlated with the structural state of microtubule ends.

scholarly journals An approximation of behind-casing hydraulic conductivity between layers from transient pressure analysis

DYNA ◽  
2019 ◽  
Vol 86 (210) ◽  
pp. 108-114
Author(s):  
Freddy Humberto Escobar ◽  
Angela María Palomino ◽  
Alfredo Ghisays Ruiz
Keyword(s):  
Hydraulic Conductivity ◽  
Transient Analysis ◽  
Test Interpretation ◽  
Well Test ◽  
Transient Pressure ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Transient Pressure Analysis ◽  
Pressure Analysis

Flow behind the casing has normally been identified and quantified using production logging tools. Very few applications of pressure transient analysis, which is much cheaper, have been devoted to determining compromised cemented zones. In this work, a methodology for a well test interpretation for determining conductivity behind the casing is developed. It provided good results with synthetic examples.

Welltest analysis of hydraulically fractured tight gas reservoirs: a field example from Perth Basin, Western Australia

2012 ◽  
Vol 52 (1) ◽  
pp. 587 ◽  
Author(s):  
Hassan Bahrami ◽  
Vineeth Jayan ◽  
Reza Rezaee ◽  
Dr Mofazzal Hossain
Keyword(s):  
Radial Flow ◽  
Second Derivative ◽  
Tight Gas ◽  
Transient Pressure ◽  
Gas Reservoirs ◽  
Type Curves ◽  
Tight Gas Reservoirs ◽  
Diagnostic Plots ◽  
Reservoir Permeability ◽  
Reservoir Flow

Welltest interpretation requires the diagnosis of reservoir flow regimes to determine basic reservoir characteristics. In hydraulically fractured tight gas reservoirs, the reservoir flow regimes may not clearly be revealed on diagnostic plots of transient pressure and its derivative due to extensive wellbore storage effect, fracture characteristics, heterogeneity, and complexity of reservoir. Thus, the use of conventional welltest analysis in interpreting the limited acquired data may fail to provide reliable results, causing erroneous outcomes. To overcome such issues, the second derivative of transient pressure may help eliminate a number of uncertainties associated with welltest analysis and provide a better estimate of the reservoir dynamic parameters. This paper describes a new approach regarding welltest interpretation for hydraulically fractured tight gas reservoirs—using the second derivative of transient pressure. Reservoir simulations are run for several cases of non-fractured and hydraulically fractured wells to generate different type curves of pressure second derivative, and for use in welltest analysis. A field example from a Western Australian hydraulically fractured tight gas welltest analysis is shown, in which the radial flow regime could not be identified using standard pressure build-up diagnostic plots; therefore, it was not possible to have a reliable estimate of reservoir permeability. The proposed second derivative of pressure approach was used to predict the radial flow regime trend based on the generated type curves by reservoir simulation, to estimate the reservoir permeability and skin factor. Using this analysis approach, the permeability derived from the welltest was in good agreement with the average core permeability in the well, thus confirming the methodology’s reliability.

Well Completion for Effective Deliquification of Natural Gas Wells

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
John Yilin Wang
Keyword(s):  
Natural Gas ◽  
Operating Cost ◽  
Gas Production ◽  
Gas Wells ◽  
Liquid Loading ◽  
Gas Recovery ◽  
Well Completion ◽  
Reservoir Permeability ◽  
Gas Fields ◽  
Gas Lift

Liquid loading has been a problem in natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells. Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing, and gas lift. All these methods are to optimize the lifting of liquid up to surface, which increases the operating cost, onshore, and offshore. However, the near-wellbore liquid loading is critical but not well understood. Through numerical reservoir simulation studies, effect of liquid loading on gas productivity and recovery has been quantified in two aspects: backup pressure and near-wellbore liquid blocking by considering variable reservoir permeability, reservoir pressure, formation thickness, liquid production rate, and geology. Based on the new knowledge, we have developed well completion methods for effective deliquifications. These lead to better field operations and increased ultimate gas recovery.

Condensate Bank Characterization from Well Test Data and Fluid PVT Properties

2006 ◽  
Vol 9 (05) ◽  
pp. 596-611 ◽  
Author(s):  
Manijeh Bozorgzadeh ◽  
Alain C. Gringarten
Keyword(s):  
Capillary Number ◽  
Gas Condensate ◽  
Test Interpretation ◽  
Well Test ◽  
Transient Pressure ◽  
Compositional Simulation ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Inertia Effects ◽  
The North

Summary Published well-test analyses in gas/condensate reservoirs in which the pressure has dropped below the dewpoint are usually based on a two- or three-region radial composite well-test interpretation model to represent condensate dropout around the wellbore and initial gas in place away from the well. Gas/condensate-specific results from well-test analysis are the mobility and storativity ratios between the regions and the condensate-bank radius. For a given region, however, well-test analysis cannot uncouple the storativity ratio from the region radius, and the storativity ratio must be estimated independently to obtain the correct bank radius. In most cases, the storativity ratio is calculated incorrectly, which explains why condensate bank radii from well-test analysis often differ greatly from those obtained by numerical compositional simulation. In this study, a new method is introduced to estimate the storativity ratios between the different zones from buildup data when the saturation profile does not change during the buildup. Application of the method is illustrated with the analysis of a transient-pressure test in a gas/condensate field in the North Sea. The analysis uses single-phase pseudo pressures and two- and three-zone radial composite well-test interpretation models to yield the condensate-bank radius. The calculated condensate-bank radius is validated by verifying analytical well-test analyses with compositional simulations that include capillary number and inertia effects. Introduction and Background When the bottomhole flowing pressure falls below the dewpoint in a gas/condensate reservoir, retrograde condensation occurs, and a bank of condensate builds up around the producing well. This process creates concentric zones with different liquid saturations around the well (Fevang and Whitson 1996; Kniazeff and Nvaille 1965; Economides et al. 1987). The zone away from the well, where the reservoir pressure is still above the dewpoint, contains the original gas. The condensate bank around the wellbore contains two phases, reservoir gas and liquid condensate, and has a reduced gas mobility, except in the immediate vicinity of the well at high production rates, where the relative permeability to gas is greater than in the bank because of capillary number effects (Danesh et al. 1994; Boom et al. 1995; Henderson et al. 1998; Mott et al. 1999).

scholarly journals Assessing the Needs to Incorporate Completion Details in a Petroleum Reservoir Simulation Model

2015 ◽  
Vol 8 (1) ◽  
pp. 16-28 ◽  
Author(s):  
Liang-Biao Ouyang
Keyword(s):  
Fluid Flow ◽  
Simulation Model ◽  
Simulation Study ◽  
Reservoir Simulation ◽  
High Rate ◽  
Petroleum Reservoir ◽  
Well Performance ◽  
Well Completion ◽  
Reservoir Permeability ◽  
Reservoir Simulation Model

Most of the current research and commercial reservoir simulators lack the capability to handle complex completion details like perforation tunnels in a simulation study. In most common applications, the simplified handling of completion complexity in reservoir simulations is not expected to introduce significant error in simulation results. However, it has been found that under certain circumstances, especially in high rate wells that have become more and more common in deepwater oil and profilic gas development, exclusion of the complex completion details in a reservoir simulation model would lead to nontrivial errors. New equations have been proposed to assess the needs to incorporate completion details in a reservoir simulation study based on the understanding of the fluid flow in a formation, the fluid flow along a wellbore and the fluid flow through perforation tunnels if exist. A series of sensitivity studies with different completion options under different flow and reservoir environments has been conducted to provide some guidance to improve well performance prediction through reservoir simulation. Impacts of key parameters like perforation density, perforation diameter, perforation length, wellbore length, borehole diameter, well completion configuration, well placement, reservoir permeability, reservoir heterogeneity, pressure drawdown, etc, have also been investigated.

Example of Internal Redundancy to Improve the Dynamics Performance of Parallel Manipulators

2012 ◽  
Author(s):  
Soheil S. Parsa ◽  
Juan A. Carretero ◽  
Roger Boudreau
Keyword(s):  
Dynamic Model ◽  
Dynamic Properties ◽  
Center Of Mass ◽  
Parallel Manipulators ◽  
Redundant Manipulators ◽  
Serial Manipulators ◽  
Numerical Example ◽  
Kinematic Singularities ◽  
First Time

In recent years, redundancy in parallel manipulators has been discussed for the cases of kinematic, actuation and branch redundancy. Some advantages of these redundant manipulators include the reduction or elimination of some types of kinematic singularities and/or an increase of their reachable and dexterous workspaces, to name a few. Internal redundancy, first introduced for serial manipulators, refers to the concept of adding movable masses to some links so as to allow to control the center of mass and other dynamic properties of some links. In this paper, the concept of internal redundancy is investigated for the first time in the context of parallel manipulators. More specifically, the 3-RRR planar manipulator, where a movable mass has been added to the distal link, is analysed. The manipulator’s dynamic model is briefly introduced and then is used to track a simple trajectory. A numerical example is shown to support the idea.

scholarly journals New IR imaging modalities for cancer detection and for intra-cell chemical mapping with a sub-diffraction mid-IR s-SNOM

2016 ◽  
Vol 187 ◽  
pp. 539-553 ◽  
Author(s):  
H. Amrania ◽  
L. Drummond ◽  
R. C. Coombes ◽  
S. Shousha ◽  
L. Woodley-Barker ◽  
...  
Keyword(s):  
Human Cancer ◽  
Single Cells ◽  
Design Feature ◽  
Chemical Mapping ◽  
Technological Readiness ◽  
New Family ◽  
Routine Basis ◽  
Cancer Biopsy ◽  
First Time ◽  
Detailed Chemical

We present two new modalities for generating chemical maps. Both are mid-IR based and aimed at the biomedical community, but they differ substantially in their technological readiness. The first, so-called “Digistain”, is a technologically mature “locked down” way of acquiring diffraction-limited chemical images of human cancer biopsy tissue. Although it is less flexible than conventional methods of acquiring IR images, this is an intentional, and key, design feature. It allows it to be used, on a routine basis, by clinical personnel themselves. It is in the process of a full clinical evaluation and the philosophy behind the approach is discussed. The second modality is a very new, probe-based “s-SNOM”, which we are developing in conjunction with a new family of tunable “Quantum Cascade Laser” (QCL) diode lasers. Although in its infancy, this instrument can already deliver ultra-detailed chemical images whose spatial resolutions beat the normal diffraction limit by a factor of ∼1000. This is easily enough to generate chemical maps of the insides of single cells for the first time, and a range of new possible scientific applications are explored.

scholarly journals Composite Test inclusive of Benford’s Law, Noise reduction and 0-1 Test for effective detection of Chaos in Rotor-Stator Rub

2021 ◽  
Author(s):  
Aman Kumar Srivast ◽  
Mayank Tiwari ◽  
Akhilendra Singh
Keyword(s):  
Noise Reduction ◽  
Dynamic Properties ◽  
Signal To Noise Ratio ◽  
Chaotic Signal ◽  
Benford’S Law ◽  
Noisy Environment ◽  
Scale Invariant ◽  
System A ◽  
Benford's Law ◽  
First Time

Abstract Segregating noise from chaos in a dynamical system has been one of the most challenging work for the researchers across the globe due to their seemingly similar statistical properties. Even the most used tools such as 0-1 test and Lyapunov exponents fail to distinguish chaos from regular dynamics when signal is mixed with noise. This paper addresses the issue of segregating the dynamics in a rotor-stator rub system when the vibrations are subjected to different levels of noise. First, the limitation of 0-1 test in segregating chaotic signal from regular signal mixed with noise has been established. Second, the underexplored Benford’s Law and its application to the vibratory dynamical rotor-stator rub system has been introduced for the first time. Using the Benford’s Law Compliance Test (BLCT), successful segregation of not only noise from chaos but also very low Signal to Noise Ratio (SNR) signals which are mainly stochastic has been achieved. The Euclidean Distance concept has been used to explore the scale-invariant probability distribution of systems that comply with Benford’s Law to separate chaos from noise. Moreover, for moderate bands of noise in signals, we have shown that the Schreiber’s Nonlinear Noise Reduction technique works effectively in reducing the noise without damaging the dynamic properties of the system. Combining these individual layers (0-1 Test, BLCT and Noise reduction) on a rotor system, a Decision Tree based method to effectively segregate regular dynamics from chaotic dynamics in noisy environment has been proposed.

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