Such concerns would only increase if the hydrate accumulations are themselves the target of development operations. The primary concern is that warm fluids rising in a wellbore from deeper reservoirs may cause gas hydrate in the neighborhood of a well or pipeline to dissociate, reducing the stability of the supporting sediments and placing significant investments at risk. Adapted from McIver (1982).Īs a result of this potential for submarine sediment dislocation, the placement of wells and seafloor-grounded platforms associated with oil and gas production is strongly influenced by the presence of gas hydrate on the sea floor or within the sediment lithology. Diagram showing the effects of gas hydrate dissociation on oceanic hillslope failures and gas release.
Failure would be accompanied by the release of methane gas, but a portion of the methane is likely to be oxidized unless the gas release is catastrophic. Submarine slope failure can follow, giving rise to debris flows, slumps, slides, and collapse depressions such as described by Dillon, et al. The hydrates in any of these cases may be a part of the solid skeleton that supports overlying sediments, which in turn support the platforms and pipelines needed for producing conventional oil and gas resources, as well as natural gas from hydrates (when this becomes economically and technically possible).Īccordingly, the potential instability of HBS is a subject of critical importance, and past researchers have described the conditions under which hydrate dissociation in HBS produces an enhanced fluidized layer at the base of the gas-hydrate zone. Each of these hydrate accumulations may affect the seafloor stability differently. Gas hydrates exist in many configurations below the sea floor, including massive (thick solid zones), continuous layers, nodules, and as widely disseminated interstitial material. Interagency Working Group Initial Report.FECM Extramural R&D Final Technical Reports.Solicitations and Funding Opportunities.Strategic Systems Analysis and Engineering.Materials Engineering and Manufacturing.
TheTeredolite bearing horizons also occurs with abundant belemnites Neohibolithes ewaldi, which is considered to be index fossil for the Early Aptian sediments. Three ichnofabrics recognized within the Ukra Hill Member are inferred to represent near shore high energy conditions (Psilonichnus ichnofabric), transgressive condition with subsequent erosion (Teredolites Ichnofabric) and shelf environment (Gyrolithes-Rhizocorallium Ichnofabric). These Teredolite bearing horizons are underlain by coarse grained cross bedded sediment with monodominant Psilonichnus tubiformis, while abundant Gyrolithes cycloides along with Rhizocorallium irregulare, R. The present study documents abundance of trace fossil Teredolite, occurring as driftwood and bedload log ground as well as re-worked log ground from the basal part of the Ukra Hill Member. The Ukra Hill Member exposed only in Western part of Kachchh basin comprises of fossiliferous shales, limestones and glauconitic sandstones in between thick unfossiliferous sandstone. Ichnological analysis of transgressive marine tongue in prograding deltaic system: Evidences from Ukra Hill Member, Western Kachchh, India Ichnological analysis of transgressive marine tongue in prograding deltaic system: Evidences from.