Pressure reading tool

An apparatus for measuring formation pressure, comprising:

• a housing having an interior chamber and an orifice extending from said chamber to an exterior of said housing such that fluids may pass into and out of said chamber in said orifice;
• a member within said chamber to induce a modulation of fluids within said chamber;
• and
• a pressure reader in hydraulic communication with said chamber.

An apparatus mounted on drill string for removing mudcake from the wall of a borehole having drilling fluid, comprising:

• a housing having a chamber with a volume, and an orifice extending from said chamber to an exterior of said housing;
• a magnetostrictive ring disposed within said chamber;
• an excitation source associated with said magnetostrictive ring and cooperating with said magnetostrictive ring to modulate said chamber volume;
• a sheathing encapsulating said magnetostrictive ring;
• and
• a pressure reader mounted on said housing and at least partially exposed to said chamber.

An apparatus connected to an external activating source for creating a pressure wave in fluid, comprising:

• a housing defining a chamber having a volume capable of receiving a fluid, said housing having an outer wall with an orifice disposed therethrough, and an inner wall having at least one access hole therethrough;
• a screen disposed within said chamber proximate said orifice;
• a magnetostrictive ring disposed within said chamber which radially expands and contracts to alternately increase and decrease said chamber volume;
• windings associated with said magnetostrictive ring and connected to said external actuating source through said access hole;
• a sheathing encapsulating said magnetostrictive ring and forming a substantially impermeable membrane between the fluid and said magnetostrictive ring, said sheathing being sufficiently elastic so as to allow unimpeded expansion and contraction of said magnetostrictive ring;
• a dampening element at least partially interposed between said magnetostrictive ring and said housing;
• and
• a pressure transducer positioned within said inner wall and at least partially exposed to said chamber.

A method of removing an impermeable membrane from the wall of a borehole, comprising:

• providing a tool having a housing defining a chamber, the housing including an orifice providing fluid communication with the chamber;
• placing the tool in the borehole adjacent the wall such that the orifice is directed toward the impermeable membrane;
• creating a pressure frequency in the fluids within the chamber;
• and
• directing pressure waves in the fluids through the orifice and against the wall to remove the impermeable membrane.

A method for determining formation pressure at a point in a borehole wall, during drilling using drilling fluids, comprising:

• (a) positioning a pressure transducer along the drill string in the vicinity of the drill bit;
• (b) flushing the borehole wall clean of mudcake using an agitated stream of drilling fluid;
• (c) receiving a formation pressure reading at the pressure transducer;
• and
• (d) transmitting the pressure reading to the surface;