Overview of wireline-logging analysis in the Aurora/JOGMEC/NRCan Mallik 2L-38 gas hydrate production research well

Abstract

In order to evaluate the productivity of gas hydrate by the depressurization method, Japan Oil, Gas and Metals National Corporation and Natural Resources Canada carried out a full-scale production test in the Mallik field, Mackenzie Delta in April 2007 and March 2008. An extensive wireline-logging program was conducted in 2007 to evaluate physical reservoir properties of gas-hydrate-bearing sediments, to determine production-test and water-injection intervals, to evaluate cement bonding, and to interpret gas hydrate-dissociation behaviour throughout the production test. New open-hole wireline-logging tools, such as the Magnetic Resonance ScannerTM, True Resistivity ScannerTM, Sonic ScannerTM, and other advanced logging tools, such as Elemental Capture SpectroscopyTM, were deployed to obtain precise data on the occurrence of gas hydrate, lithology, gas hydrate pore saturation, porosity, and permeability. Perforation interval of the production-test and water-injection zones was determined through a multidisciplinary approach, using geological-petrophysical analysis and interpretation of open-hole logging data, construction of layered reservoir models, quick reservoir numerical simulations for several perforation scenarios, and operational constraints. A gas-hydrate-bearing formation from 1093 to 1105 m KB was selected for the 2007-2008 production test, and three zones (1224-1230, 1238-1256, and 1270-1274 m KB) were selected for the injection of produced water. Cased-hole logging measurements with the Reservoir Saturation ToolTM, Accelerator Porosity SondeTM, and Sonic ScannerTM were also conducted to evaluate physical-property changes of the gas-hydrate-bearing intervals before and after the production test (time-lapse analysis). Analysis of these cased-hole logging data provided important knowledge about gas hydrate-dissociation behaviour.

Are Laboratory-Formed Hydrate-Bearing Systems Analogous to Those in Nature?

“…With further decreasing depth a gas phase would evolve and migrate with the water as two-phase flow (dot-dashed black arrow; the dot-dash signature represents two phase flow). Despite very high gas hydrate saturations of up to 90 % in sands just above the BGHS (1107 m), no free-gas-bearing sediment has been confirmed by well-log-analysis below the BGHS …”

“…Despite very high gas hydrate saturations of up to 90 % in sands just above the BGHS (1107 m), 16 no free-gasbearing sediment has been confirmed by well-log-analysis below the BGHS. 32 In the Ulleung Basin the variation of methane solubility with depth is much stronger because of the high geothermal gradient ( Figure 1B). It even has a local minimum below the BGHS at a depth of about 2700 m. As before, the left green dotted arrow marks the maximum CH 4 concentration which does not exceed the solubility limit before the water migrates into the BGHS.…”

Permeability of sediment cores from methane hydrate deposit in the Eastern Nankai Trough

“…Estimated initial effective permeability was in the range of 0.12e0.17 md. At the Mallik field on Mackenzie Delta, initial effective permeability in a highly hydrate-saturated sand layer was estimated to be lower than 1 md based on CMR logging (Fujii et al, 2012).…”

Analysis of Stratum Subsidence Induced by Depressurization at an Offshore Hydrate-Bearing Sediment

“…It is considered as a kind of high-quality clean energy in the 21st century . Since the 1990s, Canada, , the United States, Japan, and China − have successively carried out gas production tests from hydrate reservoirs in permafrost and the marine continental margin. In the latest production test, the gas production rate and duration time have been improved.…”