Abstract: A method for cleaning a helical spring screen deep in a well while filtering liquid comprises (1) injecting a high pressure hydraulic surge pulse into the spring screen for expanding the coils, (2) forcing high pressure liquid between the coils of the helical spring screen simultaneously with expanding of the coils for washing the sand from between the coils, and (3) forcing the coils together following their expansion by expanding action of a second spring for crushing and dislodging any sand therebetween the coils for removal upon subsequent spreading of the coils. A second method is disclosed likewise. Thus the methods provide for the spring coils being cleaned for a multiplicity of times without having to shut the well in for workover, thus saving workover costs and lost production.

Abstract: A method for cleaning a helical spring screen deep in a well while filtering liquid comprises (1) injecting a high pressure hydraulic surge pulse into the spring screen for expanding the coils, (2) forcing high pressure liquid between the coils of the helical spring screen simultaneously with expanding of the coils for washing the sand from between the coils, and (3) forcing the coils together following their expansion by expanding action of a second spring for crushing and dislodging any sand therebetween the coils for removal upon subsequent spreading of the coils. A second method is disclosed likewise. Methods for forming a self-cleaning helical spring screen and two modifications of a helical spring screen are disclosed herein for being cleaned for a multiplicity of times without having to shut the well in for workover, thus saving workover costs and lost production.

Abstract: Hydrocarbons are recovered from a subterranean hydrocarbon-bearing reservoir by in-situ combustion with minimum formation of water of combustion by fracturing the reservoir with a combustible fracturing mixture, burning the fracturing mixture, and thereafter injecting fluidized carbon in an inert gas carrier while at the same time injecting an oxygen-containing gas so that the fluidized carbon is burned in the fractures for thermal stimulation of production of hydrocarbons from the reservoir.