CA2579245A1 - Method of intensification of natural gas production from coal beds - Google Patents

Abstract

A method of intensification of natural gas production from the coal beds, comprising exposure of the coal bed to pressure pulsing is disclosed. An embodiment comprises exposure of the coal bed to pressure pulsing in combination with hydraulic fracturing of the coal bed. Another embodiment comprises exposure of the coal bed to pressure pulsing in combination with creation of a cavity in the coal bed by cyclically increasing pressure of the fluid in the well and depressurizing rapidly the fluid.

Claims (15)

1. A method of intensification of natural gas production from the coal beds, comprising exposure of the coal bed to pressure pulsing and hydraulic fracturing of the coal bed.

2. The method of claim 1, wherein the pressure pulses are low frequency high-amplitude pressure pulses.

3. The method of claim 1, wherein the hydraulic fracture is created in the coal bed by the steps of injecting into the coal bed a fracture fluid at high flow rates and pressures to create the fracture, further injecting a proppant in the fracture fluid to prevent closing the fracture created, and finally injecting the fracture fluid without proppant for washing the well.

4. The method of claim 3, wherein the pressure pulsing is applied to the coal bed either before creating the fracture, or during injecting the fracture fluid to create the fracture, or during injecting a proppant in the fracture fluid, or during finally injecting the fracture fluid without proppant, or during some or all said steps.

5. The method according to claim 4, comprising, before starting the hydraulic fracturing of the coal bed, the following steps:

running a pressure pulse generator into the wellbore approximately at the level of treated interval;

loading the wellbore with an incompressible fluid in order to couple the coal bed to the pressure pulse generator;
adjusting the generator to create pressure pulses of required frequency and amplitude;

transmitting the pressure pulses created by the pressure pulse generator to the coal bed through the incompressible fluid;

injecting the fracture fluid to the coal bed.

6. A method of intensification of natural gas production from the coal beds, comprising exposure of the coal bed to pressure pulsing and hydraulic fracturing of the coal bed by injecting into the wellbore a fracture fluid without proppant at high flow rates and pressures.

7. A method of intensification of natural gas production from the coal beds, comprising exposure of the coal bed to pressure pulsing and creation of a cavity in the coal bed by cyclically increasing pressure of the fluid in the well and depressurizing rapidly the fluid.

8. The method of claim 7, wherein the pressure pulses are low frequency high-amplitude pressure pulses.

9. The method of claim 8, wherein the low frequency high-amplitude pressure pulses impact the coal bed during increasing the pressure of the fluid in the well.

10. The method of claim 8, further comprising the step of cleaning the well, wherein the fluid used for transferring pressure pulses is replaced by an efficient foamy cleaning medium.

11. The method of claim 10, wherein a fluid driven generator is used for creation of the pressure pulses and the foamy cleaning medium is pumped through said generator.

12. The method of claim 10, wherein a generator for creation of the pressure pulses is placed in a nearby well, and the pressure pulsing of the coal bed is simultaneously accompanied with injecting the foamy cleaning medium in the treated well.

13. A method of intensification of natural gas production from the coal beds, comprising exposure of the coal bed to pressure pulsing, creation of a cavity in the coal bed by cyclically increasing pressure of the fluid in the well and depressurizing rapidly the fluid, and well cleaning, comprising the steps of:

running a pressure pulse generator into the wellbore at the level of treated interval in the wellbore;

loading the wellbore with an incompressible fluid in order to couple the coal bed to the pressure pulse generator;
adjusting the generator to create pressure pulses of required frequency and amplitude and transmitting the pressure pulses created through said incompressible fluid to the coal bed;

creating a pressure gradient in the near wellbore zone by injecting fluid above the pressure of the coal bed;
depressurizing rapidly the fluid in the wellbore to cause breakdown of the coal bed and produce rubblized coal;

cleaning the well by circulating efficient foamy cleaning medium across the treated interval to aid fluidization and transport of the rubblized coal to the surface.

14. The method of claim 13, comprising using a fluid discharge pressure pulse generator without a resonator, so that a pulsing jet produces cutting action on the coal bed.

15. The method of claim 13, wherein said steps are repeated after refilling the wellbore with the incompressible fluid.