Asphaltene
deposition
is one of the major flow assurance problems
in upstream and downstream crude oil recovery operations. In order
to prevent potential loss and reduce downtime due to asphaltenes,
it is critical to understand the physics of asphaltene adsorption.
This study presents a preliminary investigation of asphaltene adsorption
from crude oils onto stainless-steel surfaces using the quartz crystal
microbalance with dissipation (QCM-D) technique and proposes a theoretical
interpretation of the deposition mechanism for asphaltene molecules.
The kinetics of deposition at different concentrations was examined,
and the sizes of the deposited asphaltene molecules were estimated
from the initial adsorption kinetics. Numerical analysis of the experimental
data using the theoretical two-step deposition model was attempted,
and the optimized adsorption parameters proved to be quite close to
those values obtained for some rock types in earlier adsorption studies.
Despite asphaltene precipitation increasing with increasing heptane
percentage, the deposition of asphaltenes was found to be maximum
at 70 vol% heptane content. The performance of a commercial inhibitor
was then assessed under different conditions using the developed experimental
metrics, and the inhibitor was found to be able to reduce the maximum
deposition amount at the solubility with 70 vol% heptane fraction,
which happens to be the same condition that generates the largest
amount of deposition. The information gained on the solubility effect
and inhibitor performance is essential to help the industry better
manage asphaltene-related flow assurance problems in crude oil recovery.
Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).
Subsea pipeline transportation of wet gas over signifi cant distances to an onshore or offshore facility for processing can be a key element in the development of large offshore gas resources. Full well stream carbon steel pipelines offer substantial cost advantages over alternatives such as offshore gas dehydration or pipelines clad with corrosion-resistant alloys. However, such well streams are typically highly corrosive to carbon steel and subject to complex and variable multiphase fl ow conditions. Realizing the twin objectives of optimum capital expenditure and long-term facility integrity, therefore, requires both a comprehensive fl ow assurance approach and a robust, highly effective corrosion control program.This design approach requires close integration of fl ow assurance and corrosion technologies. Specifi cally, accurate fl ow modeling is used to predict the nature of the produced fl uids in contact with the pipe wall as a function of the location in the pipe. Corrosion inhibitor qualifi cation testing is then conducted in fl uids that simulate the range of anticipated service conditions in terms of both chemistry and hydrodynamics. This paper describes the application of enhanced fl ow modeling and corrosion testing to more accurately simulate the local top of the line environment for large diameter, sour wet gas lines and to defi ne a comprehensive inhibitor qualifi cation plan and corrosion management program. Operational, facility design and technology lessons learned in implementing these advances in a major project are presented.
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