Rudy E. Rogers

Surfactant effects on gas hydrate formation

Abstract Micellar solutions were found to increase gas hydrate formation rate and alter formation mechanism for ethane and natural gas hydrates. A critical micellar concentration (CMC) of sodium dodecyl sulfate water solution was found to be 242 ppm at hydrate-forming conditions, where CMC was best determined by hydrate induction time. At surfactant concentrations above the CMC, hydrate formation rates in a quiescent system increased by a factor greater than 700. Above the CMC, hydrates initiated subsurface around the micelle-solubilized hydrocarbon gas. Developing hydrate particles migrated and adsorbed on the water-wet cell walls at the water–gas interface, where interstitial water–surfactant solution of the packed hydrate particles continued to react at the high rate. The development overcomes major limitations of future hydrate use in an industrial-scale natural gas storage process.

Hydrocarbon gas hydrates in sediments of the Mississippi Canyon area, Northern Gulf of Mexico

Abstract The Gulf of Mexico Hydrates Research Consortium has begun installing a seafloor observatory to monitor gas hydrate outcrops and the hydrate stability zone in Mississippi Canyon Area Lease Block 118. Relevant background information concerning the Mississippi Canyon Area and gas hydrate occurrences in the northern Gulf of Mexico is presented. Microbial influences and possible scenarios of hydrate accumulation are considered. The design of the observatory was based on field data recorded in the Mississippi Canyon Area, principally lease block 118 (MC118) and the vicinity of lease block 798 (MC798). Swath bathymetry by autonomous underwater vehicle played a large part, as did seismic imaging within the hydrate stability zone and core sampling. These data and the results of their analyses are discussed in detail. Discussion and interim conclusions are presented.

Can Fractures in Soft Sediments Host Significant Quantities of Gas Hydrates

The Gulf of Mexico Hydrate Research Consortium has collected several types of data in and around Mississippi Canyon Lease Block 798 (MC798), an area of the northern Gulf of Mexico where fine-grained sediment occurs at the sea floor and where hydrates have been sampled. Swath bathymetry, heat-flow measurements, core samples, and subbottom profiles were collected. Hydrate was grown in the laboratory in sediments subsampled from the cores to demonstrate that the surficial sediments in MC798 are conducive to hydrate formation. Herein, data are presented and results discussed. It is postulated that significant quantities of hydrate could form in fine-grained sediments by filling fracture porosity produced by polygonal faulting. Analyses of cores combined with laboratory experiments indicate that conditions in MC798 are conducive to the formation of polygonal faults. Heat-flow measurements indicate that the hydrate stability zone is about 400 m (1312 ft) thick. Its upper 100 ms or so appears on two-dimensional (2-D) subbottom profiles to be fine grained. Small, near-vertical fractures indicated by features called brooms are common there. Thus, it is possible that a polygonal fault system exists in the upper 100 ms (75 m [246 ft] at 1500 m/s [4921 ft/s]). It is acknowledged that 2-D profiles cannot demonstrate this conclusively. Conclusive proof would require a three-dimensional (3-D) data set with sufficient resolution to demonstrate interconnectivity among the small faults. If polygonal faulting exists, gas and water could circulate through the fractures and be exposed to smectite-rich clays, a situation favorable to hydrate formation. X-ray images of pressure cores have documented hydrate accumulation within small, nearly vertical fractures in fine-grained sediments. Thus, it is possible that polygonal fault systems could host significant accumulations of hydrate in the Gulf of Mexico.

The MSU Micellar-Solution Gas Hydrate Storage Process for Natural Gas

Gas hydrates are clathrates where the guest gas molecules are occluded in a lattice of host water molecules. With all cavities of Type I structure occupied by methane molecules, the volume ratio of gas (at standard temperature and pressure) to water can be as high as 185 [1]. In 1942 Benesh first proposed using this unique hydrate property to store natural gas [2]. To store natural gas in gas hydrates, conceptual investigations have been carried out during the past five decades [2; 3; 4]. Even though these investigations proved the concept of storing natural gas in hydrates technically feasible, applications stayed in the laboratory stage due to complexities of the process, slow hydrate formation rates, and costs.

Resource assessment and profitability from discovering rate forecasting

ABSTRACT A partially explored basin can in trying economic times such as the present, experience a slowdown in activity, leaving the state, industry, and all concerned questioning whether undiscovered fields remain in the basin of sufficient size and quantity to justify further exploration. Questions that need to be answered concern the finding costs, development costs, and ultimate profitability associated with potential discoveries. A discovery-process model was used to answer these questions by analyzing the Black Warrior basin of Mississippi for the number and size distribution of undiscovered natural gas fields. An economic analysis then detailed costs and ultimate profitability of their development. Extensive historical data from the basin was analyzed and the log-normal distribution of fields was categorized into nine class-sizes. The Drew\Schuenemeyer discovery-process model predicted 43 undiscovered fields in class-sizes with economical potential for development having 150 BCF of gas reserves. The model predicted 300 exploratory wells could be drilled in the basin with expectations of attractive profitabilities from field discoveries. Rates of return were calculated for four gas price scenarios, and the conditions for profitable development of the undiscovered fields were determined. By using the method in any partially explored basin, one can foresee the economic justification for further exploratory drilling and foresee economic benefits from eventual production of the potential fields. This method is the most thorough and informative technique that can be applied to a basin having the potential of additional gas field discoveries. As exploration becomes more selective, this technique could become a valuable tool to many exploration programs.

Pipe viscometer study of fracturing fluid rheology

A coiled-pipe viscometer, recently developed and used for accurately evaluating the flow properties of crosslinked fracturing fluids (gels), is described, and gel responses, as determined by the pipe viscometer, to various temperature and shear histories during preparation and testing are presented. Results are presented that give insight into the mechanism of gel formation and deterioration, gel stability at high temperatures, and the possible occurrence of slip flow in the fracture. Potential is shown for the coiled-pipe viscometer to simulate fluid preparation and flow in the fracturing process. 8 refs.

Potential Mississippi oil recovery and economic impact from CO2 miscible flooding

Maturing of Mississippi oil reservoirs has resulted in a steady decline in crude oil production in the state. This paper reports that, to evaluate the potential of enhanced recovery processes, particularly in the use of the states large CO{sub 2} reserves, for arresting this trend, the subject study was performed. A computer data base of over 1315 Mississippi reservoirs was established. All reservoirs were screened for applicability of the carbon dioxide miscible process. With models developed by the National Petroleum Council and DOE, incremental oil that could be produced from the carbon dioxide miscible process was calculated. Under selected economic conditions, carbon dioxide miscible flooding with utilization of carbon dioxide from the states Norphlet formation (3-7 tcf reserves of high-purity CO{sub 2}) could produce 120 million barrels of incremental oil in Mississippi. Incremental state revenues as a consequence of this production were calculated to be

Surfactant process for promoting gas hydrate formation and application of the same

45 million of severance taxes,

Ultra-stability of gas hydrates at 1 atm and 268.2 K

50 million of corporate income taxes, and

Investigations into surfactant/gas hydrate relationship

60 million of royalty payments, expressed as present values.