Engineers have struggled to produce natural gas from marine hydrates through drilling wells in the past two decades. The producing process has not been successful due to technical complications associated with hydrate decomposition such as wellbore collapse and sand production. Industry consensus is that commercial-scale gas production remains years away due to unsolved technical and environmental issues. A new thermal method called Moving Riser Method (MRM) is proposed in this work for producing natural gas from subsea gas hydrates and its feasibility is investigated. An analytical feasibility study was conducted in this project focusing on 1) achievable temperature of injected water at the seabed hydrate reservoir, 2) achievable gas production rate under given hot water injection conditions, and 3) production system design for environmental safety. This study concludes that with today’s pipe insulation technology water temperature drops only a few degrees from sea surface level to the seafloor level in an insulated 800 m deep vertical pipe. The injected water at seafloor level will be hot enough to dissociate gas hydrate at a commercial rate with an affordable energy consumption rate. The energy production to consumption ratio (PCR) is greater than 4. It is possible to use a gas collector of reasonable size (e.g., 2m in diameter) to gather all dissociated gas from the hydrate reservoir. Result of this investigation shows that producing natural gas from gas hydrate reservoir at seabed with the MRM is technically viable, economically feasible, and environmentally safe.

The petroleum reservoirs constitute one of the most complex systems in nature that involve multiple interfaces coexisting and interacting with one another at elevated pressures and temperatures. Each of the four phases in the reservoir (solid rock, crude oil, associated gas and the brine) comprise multiple components, adding to the complexity of interfacial interactions. Furthermore, in order to recover the hydrocarbon resource, we impose processes involving the injection of water, chemicals and gases on these reservoirs, wherein the role of the interfacial interactions on multiphase flow through porous reservoir rocks becomes important. The tension at the various interfaces separating these phases of matter is a unique property in that it can reveal to us a great deal of information about the phases in contact including the direction and extent of mass transfer of components, their proximity to equilibrium, the nature of fluids distribution relative to one another, the contact angle and the spreading and adhesion behavior of liquids on solid surfaces. In this presentation we will examine, with supporting experimental data and literature findings, the multitude of roles played by interfacial tension in establishing (1) the phase behavior characteristics of solubility, miscibility, and the associated mass transfer mechanisms in multicomponent fluid systems, (2) the nature of fluids distribution in gas-oil-water in porous reservoir rocks at elevated pressures and temperatures, and (3) the spreading and adhesion characteristics in rock-oil-water-gas systems through dynamic contact angle measurements.

With the increased global demands on oil and gas, operators strive to maximize production by conducting more advanced drilling operations, such as extended reach, horizontal and high-pressure/high-temperature (HP-HT) drilling and are expanding globally into drilling unconventional resources. Unconventional gas resources offer significant gas production growth potential in the coming years, currently accounting for more than 43% of the US gas production. Tight Gas Sands (TGS) represents approximately 70% of the unconventional production and significant reserves are yet to be developed.Hydraulic fracturing of the deviated wells was the method of choice, in the late 80’s, for developing tight gas reservoirs worldwide. In the 90’s horizontal drilling became common practice as new drilling technology developed and proved to be very successful in many tight gas fields. However, conventional drilling operations caused reservoir formation damage that prevented the identification the gas production potential and resulted in missing some of the gas reservoirs. Underbalanced drilling (UBD) technology was introduced in the 90’s to minimize and prevent drilling problems associated with total losses into tight reservoirs. As a result, significant productivity gains were observed and this became a key driver to apply UBD technology in tight gas reservoir drilling. This paper provides a technical overview of the state of the art UBD technology used to develop unconventional tight gas reservoirs.