US 6,142,229 AGranted

Method and system for producing fluids from low permeability formations

AssigneeAtlantic Richfield Company

InventorsAubrey G. Branson, Jr., Michael Patrick Kelly, Robert S. Swain

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Abstract

A method and system for producing hydrocarbons from a low permeability formation through a well wherein the formation is first fractured with steam. The pressure of the produced fluids is measured at timed intervals and signals representative of these measurements are inputted into a computer which, in turn, calculates the rate of change in the pressure and compares this rate to a preferred limit of rate change. When the limit is exceeded, the computer outputs a signal to adjust a control value in the production line to keep the rate of pressure decrease within the preferred limit. When production drops below a certain level, the control valve is fully opened to "bump" the well and allow the pressure to increase to a new maximum. This new maximum pressure is then used to set a new preferred limit of pressure rate change.

Claims11

Dependent claims

A method for recovering hydrocarbons from a low permeability formation through a well to a conduit and into a production line by an operating cycle comprising a fracturing operation and a production operation, said method comprising the steps of:

(a) stimulating a formation containing hydrocarbons by injecting a heated fluid through the conduit, the well, and into the formation adjacent the well during the fracturing operation;
(b) producing hydrocarbons from said formation through the same well and conduit during said production operation and including the steps of:
(1) monitoring pressure as the hydrocarbons are passing through the well and the conduit, and transmitting signals from a pressure sensor to a computer;
(2) calculating a rate of change in the pressure based on said signals transmitted from the pressure sensor to the computer;
(3) comparing the rate of change in the pressure to an upper limit for a decreasing rate of change in the pressure, which upper limit is input into the computer;
(4) generating an output signal from the computer to a control valve when the rate of change in the pressure exceeds the upper limit;
(5) adjusting the positioning of the control valve to maintain the rate of pressure change within the upper limit;
(6) opening the control valve for a period of time to bump the pressure at the sensor;
and
(7) repeating steps (b)(1)-(b)(6) for at least one additional production cycle.

7 more elements

Dependencies are inferred from the claim text.