Annular pressure cap drilling method

1. A method for minimizing formation damage while drilling a reservoir section of an oil or gas well, comprising:

creating an Annular Pressure Control Diverter by adapting a commercial blowout preventer to be capable of being activated while a drill pipe is present and rotating and to have a top flange;

installing the Annular Pressure Control Diverter above a wellhead or casing head and below a conventional blowout preventer (BOP) equipment stack as a mechanical primary well pressure control mechanism;

drilling the well to the start of the reservoir section;

setting and cementing production casing and

drilling the reservoir section of the well using only a drilling fluid wherein the hydrostatic pressure exerted by the column of drilling fluid in the well is below the predicted pressure of fluids in the formation being drilled.

2. The method of claim 1 , the Annular Pressure Control Diverter further comprising at least one internal sealing element which does not rotate.

3. The method of claim 2 , further comprising at least one side door to enable changing the at least one internal sealing element of the Annular Pressure Control Diverter without removing the conventional BOP stack above the Annular Pressure Control Diverter.

4. A method for maximizing the capture of methane while drilling a reservoir section of an oil or gas well, comprising:

creating an Annular Pressure Control Diverter by adapting a commercial blowout preventer to be capable of being activated while a drill pipe is present and rotating and to have a top flange;

installing the Annular Pressure Control Diverter below a conventional blowout preventer (BOP) equipment stack and above a wellhead or casing head as a mechanical primary well pressure control mechanism;

drilling the well to the start of the reservoir section;

setting and cementing production casing;

using the Annular Pressure Control Diverter as a mechanical barrier to block a conventional inner annulus between the drill pipe and the production casing during drilling operations, and porting the production casing, thereby forcing drilling fluid and produced fluids to return up an outer annulus between the production casing and an intermediate casing concentric with and surrounding the production casing:

capturing all produced fluids, and

drilling the well using only a drilling fluid wherein the hydrostatic pressure exerted by the column of drilling fluid in the well is below the predicted pressure of fluids in the formation being drilled.

5. The method of claim 4 , having a return flow pattern where no drilling fluid returns up the conventional inner annulus between the drill pipe and the production casing and instead drilling fluid returns up the outer annulus between the production casing and the intermediate casing further comprising:

installing the intermediate casing attached to a casing head;

installing a flow line from the casing head to a separator;

installing the production casing concentric with and inside the intermediate casing and

installing drill pipe concentric with and inside the production casing, wherein the production casing is perforated above a lower extremity of the intermediate casing to enable the return flow of fluids from the inner annulus between the drill pipe and the production casing into the outer annulus between the production casing and the intermediate casing and hence via the casing head to the separator.

6. The method of claim 4 , the Annular Pressure Control Diverter further comprising at least one internal sealing element which does not rotate.

7. The method of claim 4 , further comprising at least one side door to enable changing the at least one internal sealing element of the Annular Pressure Control Diverter without removing the conventional BOP stack above the Annular Pressure Control Diverter.

8. A method for drilling a reservoir section of an oil or gas well employing a mechanical primary well pressure control mechanism comprising:

creating an Annular Pressure Control Diverter by adapting a commercial blowout preventer to be capable of being activated while a drill pipe is present and rotating and to have a top flange;

installing the Annular Pressure Control Diverter below a conventional blowout preventer (BOP) equipment stack and above a wellhead or casing head as the mechanical primary well pressure control mechanism

drilling the well to the start of the reservoir section;

setting and cementing production casing and

drilling the reservoir section of the well using only a drilling fluid wherein the hydrostatic pressure exerted by the column of drilling fluid in the well is below the predicted pressure of fluids in the formation being drilled.

9. The method of claim 8 , the Annular Pressure Control Diverter further comprising at least one internal sealing element which does not rotate.

10. The method of claim 8 , further comprising at least one side door to enable changing the at least one internal sealing element of the Annular Pressure Control Diverter without removing the conventional BOP stack above the Annular Pressure Control Diverter.

11. A method for drilling an oil or gas well wherein drilling fluid returns are flowed through a well head located below an all-inclusive blowout preventer stack to a drilling choke, comprising:

drilling the well to the start of a reservoir section;

installing an intermediate casing attached to a casing head;

setting and cementing production casing concentric with and inside the intermediate casing;

installing a flow line from a production casing head to a separator;

inserting an inner tubing string concentric with and inside the production casing, wherein the production casing is ported above a lower extremity of the intermediate casing to enable the return flow of fluids from an annulus between the inner tubing string and the production casing into an annulus between the production casing and the intermediate casing, to the production casing head, and hence to the drilling choke;

creating an Annular Pressure Control Diverter by adapting a commercial blowout preventer to be capable of being activated while the inner tubing string is present and rotating and to have a top flange;

installing the Annular Pressure Control Diverter as a mechanical primary pressure control mechanism below the blowout preventer stack, the Annular Pressure Control Diverter configured to selectively block the annulus between the inner tubing string and the production casing and

drilling the reservoir section of the well using only a drilling fluid wherein the hydrostatic pressure exerted by the column of drilling fluid in the well is below the predicted pressure of fluids in the formation being drilled.

12. The method of claim 11 , the Annular Pressure Control Diverter further comprising at least one internal sealing element which does not rotate.

13. The method of claim 11 , further comprising at least one side door to enable changing the at least one internal sealing element of the Annular Pressure Control Diverter without removing the blowout preventer stack above the Annular Pressure Control Diverter.