On demand annular pressure tool

A method comprising:

• drilling a well with a drill bit coupled to an on demand annular pressure tool and a drill string, the drill string coupled to a stand pipe, the on demand annular pressure tool initially in a deactivated mode;
• monitoring a fluid flow into the well and a fluid flow out of an annulus of the well;
• and
• activating the on demand annular pressure tool by sending a downlink signal from a surface of the well to the on demand annular pressure tool when the fluid flow out of the annulus drops below the fluid flow into the well, wherein the activating the on demand annular pressure tool comprises:
• closing a bore of the on demand annular pressure tool;
• pressurizing the drill string by flowing a fluid into the drill string;
• holding pressure in the drill string and the stand pipe;
• measuring annular pressure with an annular pressure sensor coupled to the on demand annular pressure tool;
• and
• sending a negative pressure pulse signal indicative of the annular pressure to a sensor in the stand pipe at the surface, the sending the negative pressure pulse signal comprising venting a volume of fluid from the bore of the on demand annular pressure tool to the annulus of the well.

A method comprising:

• drilling a well in a formation;
• determining fluid losses into the formation;
• activating an on demand annular pressure tool coupled to a bottom hole assembly of a drill string and closing a bore of the on demand annular pressure tool to trap fluid in the bore;
• increasing pressure in the bore to a first predetermined pressure by adding fluid into the drill string;
• pumping fluid into an annulus of the well to maintain an annular fluid level;
• determining an annular pressure in the well;
• venting fluid from the bore of the on demand annular pressure tool to the annulus to create a negative pressure pulse, the negative pressure pulse indicative of the annular pressure;
• and
• monitoring pressure in a stand pipe coupled to the drill string at a surface of the well and detecting the negative pressure pulse.