Occidental Oil Shale, Inc.

Occidental Petroleum

William J Bartel

Chang Y Cha

Robert S Burton, Iii

Richard D Ridley

Gordon B French

A processing zone advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. The fragmented mass has layers of formation particles of differing composition, such as kerogen content, corresponding to strata of differing composition in the formation. The processing zone advances in a direction substantially perpendicular to such layers in the fragmented mass. Kerogen in oil shale is decomposed to produce gaseous and liquid products including shale oil, and shale oil is withdrawn from the retort. At least one characteristic of the shale oil withdrawn from the retort varies in response to differences in composition of such layers of formation particles through which the processing zone advances. Such a characteristic can be a physical property of the shale oil such as viscosity or specific gravity, or a chemical property such as sulfur content or trace metal content. To determine the locus of the processing zone with respect to such layers in the fragmented mass, formation is analyzed for defining the locus of at least one such layer in the fragmented mass before retorting, and shale oil withdrawn from the retort is monitored for variation of such a characteristic corresponding to advancement of the processing zone through such a layer in the fragmented mass.

Determining the locus of a processing zone in an in situ oil shale retort

A retorting zone advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. The fragmented mass comprises layers of formation particles of differing kerogen content corresponding to strata of differing kerogen content in the subterranean formation. The retorting zone advances in a direction substantially perpendicular to such layers in the fragmented mass. Kerogen in oil shale in the retorting zone is decomposed to produce gaseous and liquid products including shale oil, and shale oil is withdrawn from the fragmented mass. The rate of shale oil production in the retort depends upon th kerogen content of such a layer in such a fragmented mass through which the retorting zone advances. To determine the locus of the retorting zone with respect to such layers in the fragmented mass, formation is assayed for kerogen content for defining the locus of at least one such layer in the fragmented mass before retorting, and the rate of shale oil production from the retort is monitored. The locus of the combustion zone can be estimated from the locus of the retorting zone so determined.

Determining the locus of a retorting zone in an oil shale retort by rate

A method for retorting oil shale in an in situ oil shale retort includes the steps of excavating a void in a subterranean formation containing oil shale and placing combustible material in the void adjacent an ignition situs. Formation is then explosively expanded toward the void to form a retort containing a fragmented permeable mass of formation particles containing oil shale, the top layer of the fragmented mass adjacent an ignition situs containing such combustible material. The combustible material is then ignited for establishing a combustion zone in the retort.

Method for establishing a combustion zone in an in situ oil shale retort

Values are recovered from a subterranean in situ oil shale retort containing a fragmented permeable mass of formation particles by passing a measuring gas through the retort to determine the presence of a blockage in the fragmented mass. If there is such a blockage, only a portion of the fragmented mass is processed and the portion of the fragmented mass having the blockage is left unprocessed. This is effected by introducing a processing gas to the retort at an intermediate location between opposing ends of the fragmented mass and withdrawing gaseous and liquid products of processing at an end of the fragmented mass remote from such blockage.

In situ oil shale retorting process using introduction of gas at an

A method of processing oil shale in which an in situ oil shale retort comprising an elongated cavity containing a fragmented permeable mass of formation particles containing oil shale is formed in a subterranean formation containing oil shale to recover liquid and gaseous products. Access to the cavity is by a drift or conduit at each end of the cavity and through a drift at an intermediate position. A processing zone is established in the fragmented mass at one end of the cavity and processing gas is introduced at that end of the retort and heating of the fragmented mass of formation particles is conducted from that end towards the other end. Initially, off gas is withdrawn at the intermediate drift. When the processing zone passes the intermediate drift, processing gas is introduced through the intermediate drift and off gas including gaseous products is withdrawn by way of the drift at the other end. As the processing zone passes the intermediate drift, processing gas is introduced at one end and off gas is withdrawn from the other end of the retort.

Multi-stage method of operating an in situ oil shale retort

An in situ oil shale retort is ignited by directing a combustible inlet gas mixture into an ignition zone extending across the top of the in situ retort and igniting the combustible mixture to create a combustion zone in the in situ retort. The ignition zone has a sufficient volume of interconnected open spaces for the movement of inlet gas through the ignition zone with minimal pressure loss, and the in situ retort below the ignition zone has sufficient void volume that inlet gas can be introduced into the ignition zone and moved downwardly through the in situ retort to the bottom. After ignition of the combustible mixture, additional quantities of a combustible mixture are directed into the ignition zone to maintain the combustion zone. Flue gases generated in the combustion zone are moved from the combustion zone toward the bottom of the in situ oil shale retort to establish a retorting zone on the advancing side of the combustion zone. When a self-sustaining combustion zone is established, introduction of combustible mixture can be terminated and an oxygen supplying gas introduced.

Method for igniting the top surface of oil shale in an in situ retort

An underground room in substantially undisturbed shale is filled with fragmented oil shale particles for in situ retorting. A comprehensive system is provided for feeding air to the top of the retort and recovering oil and flue gas from the bottom of the retort. The oil is separated from admixed water and both are recovered. Flue gas is withdrawn from the bottom of the retort, scrubbed clean and a portion may be recycled through the retort while another portion is vented or burned in a turbine. Means are also provided for passing scrubbed gas through a second spent shale retort prior to venting, burning or recycle.

Growing community of inventors

Grand Junction, CO, United States of America

William J Bartel