Mahmood Amani

Applying a Smart Technique for Accurate Determination of Flowing Oil-Water Pressure Gradient in Horizontal Pipelines

Two-phase flow of liquids in pipelines is crucial subject in many industries such as chemical and petroleum. Accurate prediction of pressure gradient will lead to a better design of an energy efficient transportation system. Although numerous studies for prediction of two-phase flowing pressure drop have been reported in the literature, the accurate prediction of this parameter has been a topic of debate in many research areas. In this article, a novel model based on least square support vector (LSSVM) was proposed for calculation of two-phase flowing pressure drop in horizontal pipes. The inputs of this model are oil and water superficial velocities, pipe diameter, pipe roughness, and oil viscosity. To develop and test the model, more than 700 experimental dataset from open literature were utilized. The results of proposed model were compared against the well-known empirical correlations. Statistical error analysis showed that the LSSVM model outperforms existing predictive models. Finally, an outlier diagnosis was performed to detect the doubtful experimental.

Mid-infrared dual frequency comb spectroscopy based on fiber lasers for the detection of methane in ambient air

We utilize mid-infrared dual frequency comb spectroscopy for the detection of methane in ambient air. Two mid-infrared frequency comb sources based on femtosecond Er:fiber oscillators are produced through difference frequency generation with periodically poled MgO-doped lithium niobate crystals and stabilized at slightly different repetition rates at about 250 MHz. We performed dual frequency comb spectroscopy in the spectral range between 2900 cm−1 and 3150 cm−1 with 0.07 cm−1 resolution using a multipass cell of ~580 m path length, and achieved the sensitivity about 7.6 × 10−7 cm−1 with 80 ms data acquisition time. We determined the methane concentration as ~1.5 ppmv in the ambient air of the laboratory, and the detection limit as ~60 ppbv for the current setup.

Detecting and Modeling Cement Failure in High-Pressure/High-Temperature (HP/HT) Wells, Using Finite Element Method (FEM)

Detecting and Modeling Cement Failure in High Pressure/High Temperature Wells Using Finite-Element Method. (December 2005) Mehdi Abbaszadeh Shahri, B.S., Petroleum University of Technology, Iran Chair of Advisory Committee: Dr. Jerome. J. Schubert A successful cement job results in complete zonal isolation while saving time and money. To achieve these goals, various factors such as well security, casing centralization, effective mud removal, and gas migration must be considered in the design. In the event that high-pressure and high-temperature (HPHT) conditions are encountered, we must attempt to achieve permeability in the set cement to prevent gas migration and to prevent any other fluid passing through to collapse the entire structure. Therefore, the design of the cement must be such that it prevents: • Micro-annuli formation • Stress cracking • Corrosive fluid invasion • Fluid migration • Annular gas pressure In HPHT cases, we need more flexible cement than in conventional wells. This cement expands more at least 2 to 3 times more in some special cases. The stress in the cement is strongly connected with temperature and pressure, as well as lithology and in-situ stress. If we can define a method which connects the higher temperature to the lower stress field, we would have the solution for one side of the equation, and then we could model the pressure (stress principles) at the designated depth and lithology. Since the stress is so dependent on temperature, the temperature variation must be accurately predicted to properly design the fluid and eliminate excessive time spent waiting on cement. In addition, a post-job analysis is necessary to ascertain zonal isolation and avoid unnecessary remedial work.

Experimental Measurements of Mechanical Parameters of Class G Cement

The new quest of unconventional resources is the achievement of well integrity which is highlighted by the inadequacy of conventional cementing procedures to provide zonal isolation. High temperatures and pressures or even post-cementing stresses imposed on the cement sheath as a result of casing pressure testing and formation integrity tests set in motion events which could compromise the long term integrity of the cement sheath due to fatigue. Knowledge of the mechanism of fatigue in cement and factors that affect it such as the magnitude of the load, strength and composition of the cement, mechanical properties of the cement and pattern of load cycles are important to achieve a realistic design of a cement system that will be subjected to fatigue loading. Such a design will go a long way to ensure the long term integrity of a well operating under downhole conditions. Finite element investigations help engineers to assess the stress magnitude and evolution for a given well configuration, but when structural calculations for casing-cement system are required, missing input parameters reduce the quality of the results. In order to have reliable data we performed an extensive experimental work using Class G cement in order to measure the principal parameters for mechanical structural calculations: compressive and tensile strength, Young modulus, Poison Ratio. The data was measured under room conditions and elevated temperature and pressure. The results were also extrapolated for a time period for more than 300 days. The paper will provide an excellent data inventory for class G cement that can be used when mechanical studies on cement, like finite element studies, are required.

Near infrared frequency comb vernier spectrometer for broadband trace gas detection.

We perform femtosecond frequency comb vernier spectroscopy in the near infrared with a femtosecond Er doped fiber laser, a scanning high-finesse cavity and an InGaAs camera. By utilizing the properties of a frequency comb and a scanning high-finesse cavity such spectroscopy provides broad spectral bandwidth, high spectral resolution, and high detection sensitivity on a short time scale. We achieved an absorption sensitivity of ~8E-8 cm-1Hz-1/2 corresponding to a detection limit of ~70 ppbv for acetylene, with a resolution of ~1.1 GHz in single images taken in 0.5 seconds and covering a frequency range of ~5 THz. These measurements have broad applications for sensing other greenhouse gases in this fingerprint near IR region with a simple apparatus.We present a femtosecond frequency comb vernier spectrometer in the near infrared with a femtosecond Er doped fiber laser, a scanning high-finesse cavity and an InGaAs camera. By utilizing the properties of a frequency comb and a scanning high-finesse cavity such a spectrometer provides broad spectral bandwidth, high spectral resolution, and high detection sensitivity on a short time scale. We achieved an absorption sensitivity of ~8 × 10(-8) cm(-1)Hz(-1/2), corresponding to a detection limit of ~70 ppbv for acetylene, with a resolution of ~1.1 GHz in single images taken in 0.5 seconds and covering a frequency range of ~5 THz. Such measurements have broad applications for sensing greenhouse gases in this fingerprint near infrared region with a simple apparatus.

An Overview of Methods to Mitigate Condensate Banking in Retrograde Gas Reservoirs

Condensate blockage is one of the major problems that have been addressed in the industry for many decades. When the reservoir fluid pressure drops below the dew point pressure during the production process, the liquid drops out of the gas phase and forms condensate in the formation. There are two scenarios that can result in a pressure drop. The first one is the pressure drop due to the flow of the reservoir fluid. The reservoir fluid flows from a high pressure of the reservoir to a lower pressure of the separators at the surface. The second scenario is the drop in reservoir pressure due to pressure depletion. During the production of gas and condensate, the reservoir pressure will decrease with time and when it drops below the dew point pressure, condensate forms everywhere inside the reservoir. The condensate dramatically reduces the gas permeability. Hence, it decreases the gas productivity. Several methods have been suggested to solve this problem such as gas injection, CO 2 Huff-n-Puff, wettability alteration, interfacial tension reduction, hydraulic fracturing, and nonconventional wells. Some of these methods have been implemented in the field and showed positive results, but each method has its own advantages and disadvantages that need to be studied further in order to improve its efficiency. This paper will give a general review of all these methods and their effectiveness in mitigating condensate banking. The decision of using a proper treatment of condensate banking can then be made based on different scenarios that are described in this paper. Key words: Mitigate condensate banking; Retrograde gas reservoirs; CO 2 Huff-n-Puff

Extension of filament propagation in water with Bessel-Gaussian beams

We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.

Rheological and wall-slip behaviors of polymer based drilling foams

This paper present experimental study conducted on rheology of hydroxyethyl cellulose (polymer) based foams. The effects of foam quality, wall-slip, and polymer concentration on foam rheology have been experimentally investigated using a circulating flow loop. Foam quality and flow rate were varied from 50 to 80 percent and 1 to 52 L/min, respectively. To identify the existence of wall-slip, tests were performed using different diameter (13.4, 19.6 and 31.8 mm ID) pipe viscometers.Experimental results show expected trends; pressure loss increased with increasing flow rate and reduced with increasing pipe diameter. Slight wall-slip was observed in the small diameter viscometer. However, the measurements obtained from other viscometers do not indicate wall-slip. All tested foams exhibited strong non-Newtonian behavior, which increases with foam quality and polymer concentration. The rheology of foams best fits the power-law fluid model. Applying regression analysis, new correlations have been developed to predict rheology of polymer-based foams.Copyright

Control of femtosecond filamentation by revivals of nonadiabatic molecular alignment

We realized control of filamentation and white light generation by using the laser induced nonadiabatic molecular alignment, as a means for transient modification of the ionizing medium. In the pump-probe experimental setup [1], the pump pulse induces periodical rotational revivals due to quantum-mechanical discreteness of the rotational eigenfrequencies of the molecules; then the delayed probe pulse experiences a propagating wake of index modification created by the pump pulse. This results in the modification of the filamentation process and the white-light signal.

Sensing methane in air with a mid-infrared frequency comb source

We exploited a mid-infrared frequency comb source as a high brightness laser source for trace gas detection in air with different path lengths. The MIR frequency comb source (Menlo Systems, Mid-IR Comb) was based on difference frequency generation with fiber lasers [1]. We employed flip mirrors to reroute the mid-infrared beam for different path lengths, including a homebuilt multipass cell of ∼584 m path length and open air paths of up to ∼40 m. The transmission spectra were recorded with an optical spectrum analyser (Yokogawa, AQ6376).