Plan view flow visualization experiments were conducted in the atmospheric surface layer that flows over the Great Salt Lake Desert at the U.S. Army Dugway Proving Ground, Dugway, Utah. Measurements were acquired on a nonconductive, polyethylene platform made flush with the desert floor. Surface conditions upstream of the measurement site were flat, devoid of vegetation, and because of the dried mud/clay/salt composition, essentially dust free. Local surface variations ranged between 1 and 3 mm, which corresponded to three to ten viscous units during the experiments. Flow visualizations were accomplished by continuously injecting theatrical fog through a tangential slit covering a smoke reservoir buried under the platform. During the visualizations, the atmospheric surface layer flow was near neutral thermal stability. Flow velocities at 2.0 m above the surface maintained directional constancy, with a magnitude of about 1.5 m/s. A single element hot-wire probe positioned near y+=3.4 was used to measure the wall shear. Visualization results indicate the existence of the pocket and streak motions seen at much lower Reynolds number. The average inner normalized streak spacing was found to be λ+=93.1, with a positively skewed, nearly lognormal distribution. The average maximum inner normalized pocket width was found to be w+=127.2, with a positively skewed distribution. The average time between pockets was determined to be T+=36.6. Comparisons are made with existing low Reynolds number results, and a brief discussion is provided regarding the physics underlying the present observations.

The increase in deepwater production in the Gulf of Mexico and other locationsaround the world has brought a corresponding increase in the use of subseamultiphase flow meters. The placement of subsea multiphase flow meters near thewells provide improved reservoir management, well diagnosis, allocation, aswell as oversight for safety. However, to realize their full potential, multiphase flow meters require timely and accurate fluid properties at meterconditions. Subsea architectures with long flow lines and risers have led tothe realization that well tests and topside samples cannot meet the needs ofthis new measurement technology. A method for ROV-deployed subsea sampling has been developed in conjunctionwith several major operators to provide a means to capture representative fluidsamples at the multiphase meter or other locations, at various times throughoutthe life of the well. The system has been tested in a high-pressure flowlaboratory, as well as in a tank, to simulate ROV deployment in deepwaterconditions. A significant feature of this sampling system is its proposal of astandardized interface. Making such an interface between the sampling systemand the process fluid available to manufacturers will relieve them from thecosts and complications of developing proprietary systems, with varied designsand procedures. Furthermore, users will have more choices of both equipment andROV vendors, since these components should be interchangeable. This paper willpresent an overview of this sampling system development and some of itsperformance characteristics. Introduction The increase in deepwater production in the Gulf of Mexico and other locationsaround the world has brought a corresponding increase in the use of subseamultiphase flowmeters. The placement of subsea multiphase flowmeters near thewell provides improved reservoir management, well diagnostics, and allocation. However, multiphase flowmeters require timely, accurate fluid properties, atmeter conditions, to realize their full potential. Subsea architectures withlong flow lines and risers have led to the realization that well tests andtopside samples cannot meet the needs of this new measurement technology. A method for a remotely operated vehicle (ROV)-operated subsea sampling systemhas been developed to provide a means to capture representative fluid samplesat the multiphase meter and other locations at various times throughout thelife of the well. The system has been tested in a laboratory and a tank tosimulate ROV deployment in subsea conditions. One attractive feature of the sampling system is the proposed standardizedinterface. A standardized interface between the sampling system and the processfluid will relieve users and manufacturers from the costs and complications ofproprietary systems with varied designs and procedures. The standardizedinterface will be made available to interested parties. This paper presents anoverview of the sampling system development and testing.

Flow rate measurement uncertainty analysis is a key methodology for addressing production allocation, reservoir performance optimization, operational questions, and regulatory issues. Until now, no unique collection of procedures has been available to estimate the total system uncertainty associated with multiphase flow meters, well test separator systems, and the pipelines connecting them, especially for commingled flow configurations. A tool to do this would assist industry stakeholders in understanding the uncertainty associated with fiscal allocation of production, reservoir management, and forecasting processing facility operations.With this need in mind, and the support of several offshore operators and DOE through the RPSEA program, the team developed a software tool with a user-friendly interface for predicting total network uncertainties for systems with subsea multiphase flow meters (MPFMs). The tool accounts for meter operating conditions, in-situ pressure -volume -temperature (PVT) properties, system configurations, and flowline/riser effects. It is anticipated that this tool will be attractive to all industry stakeholders, in order to more equitably allocate production and optimize reservoir performance. The background of the tool's development, an overview of use cases, and lessons learned from the effort will be presented.

The increase in deepwater field development in the Gulf of Mexico and other locations has brought an increase in the use of subsea multiphase flow meters (MPFMs) for individual well flow rate monitoring at or near the wellhead. Their justification usually is to obtain improved well and reservoir management, or a more verifiable allocation of production between wells, such as where the ownership or royalty rate differs amongst the wells producing to the same platform. The two most common inadequacies of subsea MPFM installations has been the insufficiency with which one can characterize the produced fluids – for measurement accuracy, and the unavailability of any supplemental measurements, even if only temporary – for measurement verification. Without these, MPFM measurements can be inaccurate, and there may be no means to verify them. Unverifiable and questionable measurements will likely go unused, and the value originally sought with the installation of the MPFM goes out of reach. Although experience with MPFMs on land and topsides, where they are accessible, has demonstrated the importance of characterizing the fluid properties from analyzed fluid samples, and having alternative means to measure flow to validate the MPFMs, subsea multiphase meter installations rarely have any facility for fluid sampling or supplemental measurement. Until recently, the development of sampling techniques has been limited and there have been no systems developed which could deploy a variety of other sensors near the MPFM for the purposes of verification. For subsea MPFMs to fulfill their original purpose of providing long-term reliable subsea wellhead measurement, MPFM installations need to have the facilities for subsea fluid sampling and subsea sensor insertion/removal, which would provide timely and accurate fluid properties at meter conditions, and a means to verify MPFM performance. Topside well tests and samples of commingled well streams cannot meet these needs. This paper describes two technology developments which address these issues: 1) a remotely operated underwater vehicle (ROV) deployed subsea sampling system, which provides a means to capture fluid samples for the purposes of fluid property determination at the multiphase meter or other locations at any time in the life of the well, and 2) an ROV-operated subsea sensor installation/removal system that enables the placement of a variety of sensors in direct contact with process fluids, and extends the flexibility and range of subsea wellhead and subsea process measurement.

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