Hydrodynamic Forces due to Oblique Wave and Current Loading on Untrenched Subsea Pipelines

2014 ◽  
Author(s):  
Johnathan Green ◽  
Terry Griffiths ◽  
Chris Craddock
Keyword(s):  
Oil And Gas ◽  
Standard Procedure ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Hydrodynamic Forces ◽  
Wave Flow ◽  
Limited Information ◽  
Independence Principle ◽  
Current Loading ◽  
The University

A number of oil and gas projects encounter significant costs to achieve subsea pipeline stabilization using present methods. The standard procedure to estimate pipeline stability is to consider the worst combination of amplitude and direction of the current and waves that the pipe will undergo during its operational lifetime. To calculate the hydrodynamic forces a common approach is to consider only the component of the fluid velocity perpendicular to the pipe axis according to the independence principle. The hydrodynamic coefficients are then taken from a case where the fluid flow is perpendicular to the pipe for similar flow characteristics. A substantial amount of research has been carried out to assess the hydrodynamic forces on pipelines with the current and wave directions collinear and perpendicular to the pipe. However, only limited information is available on pipeline hydrodynamic forces for highly oblique current and wave flow. A Computational Fluid Dynamics (CFD) analysis was carried out to investigate the effect on pipeline hydrodynamic forces for highly oblique collinear and non-collinear current and wave directions. The work was carried out as part of the STABLEpipe JIP (1) (with participation by Woodside, Chevron, The University of Western Australia, and Wood Group Kenny) which aims to achieve a step-change improvement in the approaches to stability design, especially on mobile or erodible sea beds.

Hydrodynamic Forces Acting on Objects in a Moonpool

2014 ◽  
Author(s):  
Leiv Aspelund ◽  
Bjørnar Pettersen ◽  
Jan Visscher ◽  
Tor-Bjørn Idsøe Næss
Keyword(s):  
Cross Sections ◽  
Traditional Approach ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Hydrodynamic Forces ◽  
Flow Conditions ◽  
Piv Measurements ◽  
Wave Elevation ◽  
Linear Damping ◽  
Heave Motion

Traditionally, it has often been assumed that the flow conditions in a moonpool are only moderately altered when an object is introduced therein. Moreover, the hydrodynamic forces acting on the object has typically been estimated by Morison’s equation for small volume structures, using the fluid kinematics of the empty moonpool as a basis and applying correction factors for the confined flow conditions, as for an object in a tube or a channel. To investigate the validity of the traditional approach, an experimental study on the forces acting on objects in a moonpool was performed at NTNU/MARINTEK in Trondheim, Norway in 2013. The experiments were done using a simplified 2-dimensional moonpool model which was given a forced heave motion. Two objects, both with square cross sections but of different sizes, were put inside the moonpool one at the time. The resulting wave elevations inside the moonpool and the forces acting on the objects were recorded and analyzed. To get a deeper understanding of the flow characteristics in the moonpool, PIV measurements were used to obtain the fluid velocity fields. The experiments revealed that even moderately sized objects (relative to the size of the moonpool) change the fluid motions in the moonpool to a large extent; the overall wave elevation amplitude is strongly reduced and the resonance period is altered. A consequence of this is that there is a large discrepancy between the hydrodynamic forces acting on the objects measured in the experiments and the forces calculated using the traditional approach. The PIV results showed the formation of vortices at the inlet of the moonpool and at the edges of the objects, which is the main source of non-linear damping of the wave elevation inside a moonpool.

scholarly journals HYDRODYNAMIC FORCES ON A CIRCULAR CYLINDER DUE TO COMBINED WAVE AND CURRENT LOADING

1984 ◽  
Vol 1 (19) ◽  
pp. 191
Author(s):  
Yuichi Iwagaki ◽  
Toshiyuki Asano
Keyword(s):  
Circular Cylinder ◽  
Lift Force ◽  
Hydrodynamic Force ◽  
Flow Characteristics ◽  
Hydrodynamic Forces ◽  
Transverse Force ◽  
Particle Movement ◽  
Mass Coefficient ◽  
Line Force ◽  
Current Loading

The hydrodynamic force acting on a circular cylinder in a wavecurrent co-existing field and its generating mechanism are discussed. This study focuses on the asymmetries of both the water particle movement and the resultant vortex property with respect to the cylinder, which produce inherent characteristics in the hydrodynamic forces in the wave-current co-existing field. First of all, the vortex property around a circular cylinder in the wave-adverse current co-existing field has been examined by flow visualization tests. It has been found that the vortex property depends on the flow characteristics around the trough phase when the wave-current composite velocity becomes maximum and can be represented with a newly proposed K.C. number for the co-existing field. Secondly, the characteristics of the in-line force has been made clear by evaluating the drag coefficient and the mass coefficient in the expanded Morison's equation for the co-existing field. These coefficients can be well arranged by (/CC. )•$, which is one of the newly proposed K.C. numbers, and their characteristics coincide with the existing results in the wave only field. The in-line hydrodynamic force in the co-existing field can be explained sufficiently by considering the vortex property in the same manner as clarified in the wave only field. Thirdly, the characteristics of the transverse force (lift force) are discussed in connection with the vortex properties. It has also been found that the fluctuating frequency of the lift force is synchronized with the loading wave frequency.

scholarly journals Tablet Disintegration and Dispersion under In Vivo-like Hydrodynamic Conditions

Pharmaceutics ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 208
Author(s):  
Jan Lenz ◽  
Frederik Fuest ◽  
Jan Henrik Finke ◽  
Heike Bunjes ◽  
Arno Kwade ◽  
...  
Keyword(s):  
Fluid Velocity ◽  
Hydrodynamic Forces ◽  
Surface Erosion ◽  
Strong Impact ◽  
The Novel ◽  
Limited Information ◽  
Hydrodynamic Conditions ◽  
Tablet Disintegration ◽  
Novel Method

Disintegration and dispersion are functional properties of tablets relevant for the desired API release. The standard disintegration test (SDT) described in different pharmacopoeias provides only limited information on these complex processes. It is considered not to be comparable to the biorelevant conditions due to the frequent occurrence of high hydrodynamic forces, among other reasons. In this study, 3D tomographic laser-induced fluorescence imaging (3D Tomo-LIF) is applied to analyse tablet disintegration and dispersion. Disintegration time (DT) and time-resolved particle size distribution in close proximity to the tablet are determined in a continuously operated flow channel, adjustable to very low fluid velocities. A case study on tablets of different porosity, which are composed of pharmaceutical polymers labelled with a fluorescent dye, a filler, and disintegrants, is presented to demonstrate the functionality and precision of the novel method. DT results from 3D Tomo-LIF are compared with results from the SDT, confirming the analytical limitations of the pharmacopoeial disintegration test. Results from the 3D Tomo-LIF method proved a strong impact of fluid velocity on disintegration and dispersion. Generally, shorter DTs were determined when cross-linked sodium carboxymethly cellulose (NaCMCXL) was used as disintegrant compared to polyvinyl polypyrrolidone (PVPP). Tablets containing Kollidon VA64 were found to disintegrate by surface erosion. The novel method provides an in-depth understanding of the functional behaviour of the tablet material, composition and structural properties under in vivo-like hydrodynamic forces regarding disintegration and the temporal progress of dispersion. We consider the 3D Tomo-LIF in vitro method to be of improved biorelevance in terms of hydrodynamic conditions in the human stomach.

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

A New Technical Standard Procedure to Measure Stimulation and Gravel-pack Fluid Leak-off under Dynamic Conditions

2015 ◽  
Author(s):  
Mahmoud Asadi ◽  
Brain Ainley ◽  
David Archacki ◽  
Eric Aubry ◽  
Harold Brannon ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Standard Procedure ◽  
Oil And Gas Industry ◽  
Testing Procedure ◽  
Technical Standard ◽  
Gas Wells ◽  
Dynamic Conditions ◽  
Oil And Gas Wells ◽  
Static Conditions ◽  
Gravel Pack

Abstract Historically, leak-off analyses of stimulation fluids have been performed using in-house laboratory procedures. The lack of industry standard procedures to perform leak-off and wall building coefficient analyses of stimulation fluids has introduced inconsistency in both results and reporting for many years. A technical standard adopted in 2006 by both API and ISO for static conditions has provided the oil and gas industry with the first standardized procedure to measure and report leak-off1. However, the more complex testing under dynamic conditions was not addressed. As a result, a group of industry experts have compiled their years of experiences in developing a new technical standard to measure the leak-off characteristics of stimulation and gravel-pack fluids under dynamic flow conditions. Stimulation and gravel-pack fluids are defined, for the purpose of this technical standard, as fluids used to enhance production from oil and gas wells by fracturing and fluids used to place filtration media to control formation sand production from oil and gas wells. Leak-off is the amount of fluid lost to porous media during these operations. The leak-off procedure was developed through the colaberation of several industry companies by evaluating numerous in-house laboratory techniques and conducting round robin testing to ensure that any modifications to these procedures were reliable and repeatable. The new standard provides a step-by-step procedure that includes fluid preparation, experimental equipment design, testing procedure and data analyses for fluids exhibiting viscosity controlled leak-off or wall building characteristics. Example calculations are reviewed within this paper.

Dissolution of Sulfates and Sulfides Field Scales by Developed Scale Dissolver

2021 ◽  
Author(s):  
Hany Gamal ◽  
Salaheldin Elkatatny ◽  
Dhafer Al Shehri ◽  
Mohamed Bahgat
Keyword(s):  
Oil And Gas ◽  
Flow Characteristics ◽  
Compositional Analysis ◽  
Oil And Gas Industry ◽  
Acid System ◽  
Gas Industry ◽  
Petroleum Production ◽  
Study Results ◽  
Temperature Levels ◽  
Dissolution Efficiency

Abstract Oil and gas industry deals with fluid streams with different ions and concentrations that might cause scale precipitation. The scale precipitation, will thereafter, affect the fluid flow characteristics. Many problems will be raised by the scale deposition that affects the overall petroleum production. This paper aims to develop a non-corrosive acid system with high dissolution efficiency for field complex scales that have sulfates and sulfides minerals. The paper provided a series of lab analysis that covers the compositional analysis for the collected scale sample, and evaluating the developed acid system for compatible and stable properties, dissolution efficiency, and the corrosive impact. A field scale sample that has a composite chemical composition of paraffin, asphaltene, sulfides and sulfates compounds with different weight percentages by employing the diffraction of X-ray technology. Developing the new scale dissolver was achieved by specific compositional study for the organic acids to achieve high dissolution efficiency and low corrosive impact for the field treatment operations. The study results showed the successful scale removal for the developed dissolver at low temperature of 95 and 113 °F for surface treatment jobs. The dissolution efficiency recorded 62 and 71 % for 17 hours at the temperature levels respectively. The fluid showed a stable and compatible performance and has a pH of 12. The corrosion test was conducted without any scale inhibitors and the results showed the low corrosion effect by 0.0028 lbm/ft2. The obtained successful results will help to dissolve such complex field scales, maintain the well equipment, and maintain the petroleum production from scale issues.

Dynamic Response Interaction of Vibrating Offshore Pipeline on Moving Seabed

2006 ◽  
Vol 129 (2) ◽  
pp. 107-119 ◽  
Author(s):  
Vincent O. S. Olunloyo ◽  
Charles A. Osheku ◽  
Ayo A. Oyediran
Keyword(s):  
Dynamic Response ◽  
Oil And Gas ◽  
Fluid Velocity ◽  
Gas Industry ◽  
Offshore Pipeline ◽  
Internal Fluid ◽  
Geomechanical Property ◽  
Sediment Cover ◽  
The Subject ◽  
Oil Gas

The dynamic response interaction of a vibrating offshore pipeline on a moving seabed is herein investigated where the pipeline is idealized as a beam vibrating on an elastic foundation. This problem is of relevance in offshore exploration where pipelines are laid either on or buried in the seabed. When such pipes carry oil and gas, the undulating topography of the sea floor and the internal motion of the fluid subject the entire structure to vibration due to bending forces and form the subject of our study. Our analysis revealed that in general, the seabed acts either as a damper or as a spring and in particular when we have sedimentation, the seabed geology permits the geomechanical property of the sediment cover to act only as a damper. As expected, external excitation will increase the response of these pipes for which an amplification factor has been derived. For soft beds, high transverse vibrations were dampened by increasing the internal fluid velocity whereas they became amplified for hard beds. These results are of contemporary interest in the oil/gas industry where deep sea exploration is now receiving significant attention.

Intellectual Property Ownership in a University Setting

2022 ◽  
pp. 251512742110572
Author(s):  
Lizhu Y. Davis ◽  
Lynn M. Forsythe ◽  
John M. Mueller
Keyword(s):  
Intellectual Property ◽  
Graduate Student ◽  
Oil And Gas ◽  
Hard Rock ◽  
Property Ownership ◽  
The University ◽  
A Company ◽  
University Setting

Drilling through hard rock to explore for underground oil and gas is especially complicated in geographic areas where the sub-layer is full of dense and impenetrable rock. Charlie Scent, an Engineering Professor working at a university, undertook research to solve this dilemma and developed a solution after approximately 20 years of effort. To commercialize the technology, Scent collaborated with one of his PhD students and formed a company. Through the commercialization process, friction developed among the participants—Scent, the graduate student, and the university. This discord brought to light several important questions regarding intellectual property that is created in a university setting. This case is about who owns intellectual property and decreasing the probability that there will be friction between the individuals who are at the heart of an invention.

Fluid Power in Large Downhole Seismic Sensor Arrays

2000 ◽  
Author(s):  
Jack H. Cole
Keyword(s):  
Oil And Gas ◽  
Sensor Arrays ◽  
Fluid Power ◽  
University Of Arkansas ◽  
Enabling Technology ◽  
Successful Development ◽  
Deep Well ◽  
Petroleum Companies ◽  
Receiver Arrays ◽  
The University

Abstract High-resolution subsurface seismic imaging that places sources and receivers in wellbores is an emerging exploration technology that can help petroleum companies find and recover more oil and gas. Successful commercialization of this enabling technology requires the development of receiver arrays that can couple fifty or more three-component sensor modules to the wellbore in a reliable manner. Although electrical clamping systems have been successfully used in small arrays, hydraulic clamping is required for more than ten modules. Both inflatable-bladder and cylinder-actuated clamp arrays have been designed However, when arrays must operate in 200° C environments, elastomer bladders become unsuitable. Research at the University of Arkansas has produced a failsafe fluid power system design makes feasible the successful development of large seismic sensor arrays that can operate in deep well bores.

Simulation of flow characteristics for leak detection in oil and gas pipeline network

2021 ◽  
Author(s):  
B. Manshoor ◽  
A. Khalid ◽  
I. Zaman ◽  
D. Hissein Didane ◽  
N. F. F. Zulkefli
Keyword(s):  
Oil And Gas ◽  
Flow Characteristics ◽  
Leak Detection ◽  
Gas Pipeline ◽  
Pipeline Network
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