Browsing by Subject "gulf of mexico"
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Item An Experimental Setup to Study the Settling Behavior of Epoxy Based Fluids(2012-07-16) El-Mallawany, Ibrahim IsmailThis thesis is part of a project funded by the Minerals Management Service (MMS) (now Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE)) to study the use of epoxy to plug hurricane damaged wells. Some of the wells destroyed by hurricanes are damaged to an extent that vertical intervention from the original wellhead is not possible. These wells have to be plugged to prevent future flows through the well to protect the environment. Cement is usually the preferred plugging material because it is very cheap compared to other materials like epoxy. However, cement can easily get contaminated by sea water or brines present in wells as completion fluids. Therefore, to be able to use cement it has to be placed at the bottom of the well by drilling an offset well all the way to the bottom of the original well. Epoxy, on the other hand, being much more chemically stable can be placed at the very top of the well and let to settle by gravity without fearing contamination. Therefore, in wells described above, epoxy can be much more economical than cement. Placing epoxy at the top of a well and letting it settle by gravity can also be more economical than using cement in other situations such as in a leaking annulus of a well where circulation in that annulus is not possible, or if a well that has been previously plugged starts leaking again after the rig has been removed. Placing epoxy in the manner described can be achieved without using a rig and therefore, would be much more economical than cement. One of the most important factors in this process is to be able to predict the settling velocity of the epoxy to be able to determine the required setting time of the epoxy so that the epoxy does not set prematurely. In addition, it is important to evaluate whether the epoxy can successfully settle to the bottom and how much of it will adhere to the pipe walls while freefalling. This thesis aims to design, build and run an experimental setup that would help study the settling velocity of epoxy. Some experiments were conducted to assess the effect of different parameters that might affect the settling velocity of the epoxy such as the epoxy?s density, the annulus size and the inclination angle. The results show that the settling velocity was proportional to the epoxy?s density. Also the settling speed was almost double in experiments done at an angle compared to experiments done at vertical position. The annulus size did not have any clear effect on the settling speed. The adhesion to the pipe walls was found to be proportional to the epoxy?s viscosity and angle of inclination and was inversely proportional to the annulus size.Item Salt Control on Sedimentary Processes in Early Pleistocene: Ship Shoal South Addition Blocks 349-358, Gulf of Mexico.(Texas A&M University, 2004-09-30) Syarif, MunjiThe interpretation of 3D seismic data from Ship Shoal South Addition Blocks 349-358, Gulf of Mexico shows a complex interaction between salt, faults, and sedimentary strata. Reconstruction of the geometry of early Pliestocene (about 3.65 Ma) through recent salt and associated sediments reveals the evolution of a supralobal basin in the study area. The basin depocenter shifted from the northeastern part to the center of the study area through time. A small, bulb-shaped, salt-stock structure occurs in the northwest, and a salt sheet structure is present in the southeastern part of the study area. Those structures are part of a pennant-shaped structure bounded by counter regional faults trending northeastward. Salt movements created instability and triggered extensive faulting of the overlying strata. Three-dimensional reconstruction suggests that salt blocked the sediment during the early Pleistocene. The sediment was diverted around the salt high on both east and west sides of the salt body to the southwest and southeast. Stratigraphic interpretation of the interval between 1.35 Ma and 1.95 Ma led to the identification of a highstand systems tract (HST), a transgressive systems tract(TST), and two lowstand systems tracts (LST). The strata are developed normally in the depocenter area, whereas the strata at the basin margin were deformed by salt movement and faulting. Each systems tract is uniquely associated with a certain seismic facies. Three seismic facies were identified associated with LST, TST, and HST. Additionally, seismic sections reveal channel geometries in the LST. Seismic attribute analysis elucidates facies distribution in the systems tracts. Because of its ability to move, to divert sediment, to create instability, and to block sediment transport pathways, salt exercises the main control on the sedimentary processes in the study area.Item Seasonal and interannual differences in surface chlorophyll stocks and integrated water column chlorophyll stocks in the northeastern Gulf of Mexico(Texas A&M University, 2005-11-01) Fletcher, William WallerichDuring the Northeastern Gulf of Mexico Chemical and Hydrography study (NEGOM-COH), nine oceanographic cruises were fielded during the spring, summer and fall seasons from November 1997 to August 2000. Surface chlorophyll-? fluorescence, salinity, and temperature data were logged once a minute from the R/V Gyre and subsurface chlorophyll-? fluorescence, salinity, temperature, and nutrients were profiled when the ship stopped to make stations. Each cruise occupied 94-98 stations, partitioned among 11 cross-margin transects of water depths between 10 m to 1000 m. Overall chlorophyll-? abundance within the study area is forced by the amount of freshwater discharge. Seasonal and interannual differences are largely determined by the monthly mean streamflow for the major rivers within the NEGOM area, particularly the Mississippi River. However, an important forcing function for transport of river water to the outer continental shelf and slope is the periodic presence of anticyclonic slope eddies. Especially when these slope eddies were centered south and east of the Mississippi River delta, they entrained and so redistributed low salinity green water to a wider area within the NEGOM region than could be predicted by mean monthly streamflow alone. The mean surface chlorophyll-? concentrations, and in particular the distribution of relatively high surface chlorophyll-? concentrations off-shelf, were strongly dependent upon entrainment of freshwater by these slope eddies, especially during the three summer cruises. Interannual variability in the summertime entrainment of low salinity green water was driven by summer-to-summer differences in sea surface height (SSH) of the slope eddy(s), and in how far they extended on margin. Satellite observations of ocean color showed that freshwater entrainment by anticyclonic eddies persisted for a temporal scale of several weeks each summer. Satellite-derived surface chlorophyll-? concentrations were positively correlated with in situ measurements of surface chlorophyll-?, with greatest agreement between satellite and ship measurements of surface chlorophyll-? at concentrations <1.5 mg/m3. Because subsurface chlorophyll-? concentrations were often elevated at depths greater than the first optical depth, satellite measurements of chlorophyll-? concentration generally underestimated integrated chlorophyll-? standing stocks within the euphotic zone.