Analysis of a Production Well Through Sediments Containing Gas Hydrates

by R. J. Wittebolle, Univ of Alberta, Dep of Civil, Engineering, Edmonton, Alberta, Canada,
D. C. Sego, Univ of Alberta, Dep of Civil, Engineering, Edmonton, Alberta, Canada,



Document Type: Proceeding Paper

Part of: Civil Engineering in the Arctic Offshore

Abstract:

In some of the petroleum reservoirs recently discovered north of the Arctic Circle, production wells extend through thick permafrost. Several authors have reported zones of gas hydrate associated with those areas. A potential problem exists when warm oil from deep producing formations flows up the producing well, losing heat as it passes through the hydrate zones. The resulting radial thaw decomposition of the solid gas hydrate in turn may initiate settlement in the surrounding soil and/or may generate loads on the well casing due to the insitu gas pressure build up. A finite element study using the ADINAT program has produced a temperature distribution with time for a producing oil well through a layered stratigraphy of frozen sand, sand with hydrate, and shale layers. The analysis shows that the pressure buildup due to hydrate decomposition does not appear to be a serious technical problem.

Subject Headings: Wells (oil and gas) | Hydration | Temperature distribution | Soil gas | Finite element method | Soil settlement | Soil pressure | Arctic

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