US 5,377,756 AGranted

Method for producing low permeability reservoirs using a single well

AssigneeMobil Oil Corporation

InventorsPaul S. Northrop, James L. Wilson

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Abstract

A method for recovering connate fluids (e.g. oil) from a low permeability subterranean reservoir (e.g. diatomite) through a single wellbore. Upper and lower intervals are fractured from the wellbore that the fractured intervals only partially overlap, thereby leaving a partial, natural barrier formed of random-spaced, low permeable areas along the interface between the fractured intervals. This partial barrier improves the sweep efficiency of a drive fluid (e.g. water) which is injected into the lower fractured interval by forcing it to spread outward into the reservoir before it is flows through the upper fractured interval. The drive fluid is injected at approximately the same rate as that at which the fluids are produced so that displacement of oil occurs primarily due to imbibition.

Claims10

Dependent claims

A method for recovering connate fluids from a low permeability subterranean reservoir, said method comprising:

completing a wellbore into said reservoir;
fracturing said reservoir from a first position within said wellbore to create a first vertical fracture system within said reservoir;
fracturing said reservoir from a second position within said wellbore to create a second vertical fracture system within said reservoir;
said second position being spaced from said first position within said wellbore whereby there will be only some of the fracture(s) in said first vertical fracture system overlap some of the fracture(s) in said second vertical fracture system whereby a natural, partial barrier to flow is formed between said fracture systems;
and
injecting a drive fluid into one of said first or second fracture systems and producing said connate fluids through the other of said first or second fracture systems.

3 more elements

Dependencies are inferred from the claim text.