US 5,489,740 AGranted

Subterranean disposal of wastes

AssigneeAtlantic Richfield Company

InventorPaul A. Fletcher

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Abstract

Toxic wastes including naturally occurring radioactive materials are disposed of into subterranean earth formation zones which are bounded both above and below by zones which have higher in situ compressive stresses. The materials are prepared in a slurry of finely ground solids and a carrier liquid and are injected into a fracture created in the disposal zone by a process which includes initiating and extending the fracture with a fracturing fluid having a filter cake building solids material entrained therein to build a sealant layer on the fracture faces, The fracture fluid is followed by injection of the waste material which is followed by injection of more fracture fluid and/or a clear liquid such as fresh water or seawater to remove all toxic material from the injection well and the vicinity thereof. The fracture is then allowed to close to confine the waste material therein.

Claims10

Dependent claims

A method for disposing of waste material in a subterranean earth formation comprising the steps of:

selecting a zone in said earth formation having an in situ horizontal compressive stress which is, over a predetermined height of said zone, less than the in situ horizontal compressive stress of said earth formation above and below said zone, respectively;
placing a wellbore in communication with said zone;
injecting a fracturing fluid into said zone to generate at least one substantially vertical fracture in said zone, at least a predetermined quantity of said fracturing fluid having a particulate solid sealant material therein for forming a filter cake on opposed surfaces of said fracture;
injecting waste material into said fracture after said fracturing fluid to occupy a predetermined volume of said fracture;
injecting a quantity of a fluid consisting of one of water and seawater into said zone after the injection of said waste material to displace said waste material away from said well and within said fracture;
injecting a quantity of fluid containing said sealant material into said fracture after the injection of said waste material and prior to the injection of said one of water and seawater;
and
allowing said fracture to close to confine said waste material therein.

5 more elements

Dependencies are inferred from the claim text.