Two-pass method for developing a system of in situ oil shale retorts
US4397502A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 9, 1981 |
| Grant date | Aug 9, 1983 |
| Priority date | — |
| Expiry date | Feb 9, 2001 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/305
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A two-pass in situ oil shale retorting system uses two separate gas levels for withdrawing off gas from producing in situ oil shale retorts. During a first pass of retorting through an oil shale tract, spaced apart groups of in situ oil shale retorts are formed, leaving intervening barrier pillars of unfragmented formation between adjacent groups of retorts. During retorting, off gas from the retorts formed in the first pass is withdrawn to a first gas level drift system. Thereafter, during a second pass of retorting, intervening groups of in situ oil shale retorts are formed in the intervening barrier pillars between the groups of in situ retorts formed in the first pass. During retorting in the retorts formed in the second pass, off gas is withdrawn to a second gas level drift system that is formed at a different level and isolated from the first gas level drift system so that gas flow between the two gas levels is avoided. This permits both passes of retorting operations to progress across the oil shale tract at the same time with the second pass operations being only a few years behind the first pass.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.