Valve for communication of a measurement while drilling system

A valve for communication of a measurement while drilling system, the valve comprising:

• a first structure having a central portion and one or more elongate portions radially extending from the central portion;
• and
• a second structure having one or more portions which substantially bound a single unitary orifice region comprising a central orifice region and one or more elongate orifice regions radially extending from the central orifice region, wherein the central portion has a maximum inscribed circle encircling a rotation axis and having a first radius and the central orifice region has a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius,
• wherein at least one of the first structure and the second structure is configured to be rotated about the rotation axis to produce a relative rotation between the first structure and the second structure such that a flow path through which mud can flow is defined by and bounded at least in part by the first structure and the second structure and varies as the at least one of the first structure and the second structure rotates about the rotation axis, the flow path varying between a first configuration when the first and second structures are in a maximally closed position and a second configuration when the first and second structures are in a maximally open position, wherein mud flowing through the flow path in the first configuration experiences a first pressure difference and mud flowing through the flow path in the second configuration experiences a second pressure difference which is less than the first pressure difference.

A valve for communication of a measurement while drilling system, the valve comprising:

• a first structure comprising a central portion and one or more elongate portions radially extending from the central portion, the central portion comprising a hub and the one or more elongate portions comprising a plurality of blades radially extending from the hub;
• and
• a second structure comprising one or more portions which substantially bound a central orifice region and one or more elongate orifice regions radially extending from the central orifice region, the one or more portions comprising an outer ring and a plurality of portions radially extending from the outer ring towards a center region of the second structure, the central portion having a maximum inscribed circle encircling a rotation axis and having a first radius and the central orifice region having a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius,
• wherein at least one of the first structure and the second structure is configured to be controllably rotated about the rotation axis to produce a relative rotation between the first structure and the second structure such that the first structure and the second structure define a flow path through which mud can flow and which varies as the at least one of the first structure and the second structure rotates about the rotation axis, the flow path having a flow area projected in a plane substantially perpendicular to the rotation axis and varying between a minimum flow area when the first and second structures are in a maximally closed position and a maximum flow area when the first and second structures are in a maximally open position, the maximum flow area radially extending a maximum first distance between the hub and the outer ring and the minimum flow area radially extending a maximum second distance between the hub and the one or more portions, wherein the maximum second distance is between 10% and 90% of the maximum first distance.

A method of fabricating a valve for communication of a measurement while drilling system, the method comprising:

• providing a first structure having a central portion and one or more elongate portions radially extending from the central portion;
• and
• providing a second structure having one or more elongate portions which substantially bound a central orifice region and one or more elongate orifice regions radially extending from the central orifice region, wherein the central portion has a maximum inscribed circle encircling a rotation axis and having a first radius and the central orifice region has a maximum inscribed circle encircling the rotation axis and having a second radius greater than the first radius, wherein at least one of the first structure and the second structure is configured to be rotated about the rotation axis to produce a relative rotation between the first structure and the second structure such that a flow path through which mud can flow varies as the at least one of the first structure and the second structure rotates about the rotation axis, the flow path varying between a first configuration when the valve is in a maximally closed position and a second configuration when the valve is in a maximally open position, the flow path defined at least by the first structure and the second structure, the valve having a maximum differential pressure across the valve when in the maximally closed position and having a minimum differential pressure across the valve when in the maximally open position;
• selecting a first angular width of the one or more elongate portions about the rotation axis and a second angular width of the one or more elongate orifice regions about the rotation axis;
• and
• after selecting the first and second angular widths, selecting a first radial extent of the central portion of the first structure and a second radial extent of the one or more elongate portions of the second structure.