Method and apparatus for differential pressure measurement

A method for monitoring the flow rate of a fluid flowing through a wellbore, comprising the steps of:

• placing a differential pressure conduit in the wellbore, the differential pressure conduit defining an internal bore and adapted to create a differential pressure, the differential pressure conduit defining first and second pressure measuring stations axially spaced along the differential pressure conduit;
• measuring a first pressure at the first pressure measuring station using a first pressure sensor having a first Wheatstone bridge configured to include a first signal point and adapted to generate a first pressure measurement signal indicative of the first pressure measured by the first pressure sensor at the first signal point;
• measuring a second pressure at the second pressure measuring station using a second pressure sensor having a second Wheatstone bridge configured to include a second signal point and adapted to generate a second pressure measurement signal indicative of the second pressure measured by the second pressure sensor at the second signal point;
• and
• calculating the flow rate of a fluid flowing through the differential pressure conduit by determining the pressure differential between the first and second pressure measuring stations based on the first pressure measurement signal taken from the first signal point and the second pressure measurement signal taken from the second signal point, wherein the first and second signal points are symmetrical with respect to the first and second Wheatstone bridges.

A system for determining pressure differences of a fluid flowing through a differential pressure conduit positioned in a wellbore, the system comprising:

• a first pressure sensor positioned at a first pressure measuring station, the first pressure sensor having a first Wheatstone bridge adapted to generate a first pressure measurement signal indicative of a first pressure measured by the first pressure sensor at a first signal point;
• and
• a second pressure sensor positioned at a second pressure measuring station, the second pressure sensor having a second Wheatstone bridge adapted to generate a second pressure measurement signal indicative of a second pressure measured by the second pressure sensor at a second signal point;
• wherein the calculation of the pressure differential between the first and second pressure measuring stations is based on the first pressure measurement signal taken from the first signal point and the second pressure measurement signal taken from the second signal point, wherein the first and second signal points are symmetrical with respect to the first and second Wheatstone bridges.

A method comprising the steps of:

• placing, at a first pressure measuring station in a differential pressure conduit adapted to be positioned in a wellbore, a first pressure sensor having a first Wheatstone bridge adapted to generate a first pressure measurement signal indicative of a first pressure measured at the first pressure measuring station;
• and
• placing, at a second pressure measuring station in the differential pressure conduit, a second pressure sensor having a second Wheatstone bridge adapted to generate a second pressure measurement signal indicative of a second pressure measured at the second pressure measuring station, the differential pressure conduit defining an internal bore and adapted to create a differential pressure at the first and second pressure measuring stations, the first and second pressure measuring stations being axially spaced along the differential conduit;
• wherein the first Wheatstone bridge and the second Wheatstone bridge are homogeneous and have similar characteristics with respect to at least one of a temperature sensitivity, a pressure sensitivity, and a non-linearity, the similar characteristics being within a range of 0.01 percent to 10 percent.