Patent ID: 11946370
Assignee: SCHLUMBERGER TECHNOLOGY CORPORATION
Field: Measurement (Instruments)
Classification: CPC E  G | IPC E  G

Claim 0:
1. A method for determining asphaltene onset pressure of a formation fluid, the method comprising:
a. transmitting an optical signal through a sample of the formation fluid;
b. detecting the optical signal transmitted through the formation fluid sample;
c. decreasing a pressure of the formation fluid sample at a first controlled depressurization rate while monitoring the optical signal transmitted through the formation fluid sample;
d. using results from (c), determining a first pressure at which a change in the optical signal from asphaltene flocculation occurs;
e. repressurizing the formation fluid sample to, or introducing another sample of the formation fluid at a pressure above the first pressure determined at (d);
f. repeating (a) to (d) at least once using at least a second, different depressurization rate to determine a second pressure at which the change in the optical signal from the asphaltene flocculation occurs;
g. fitting at least the determined first and second pressures as a function of the first and second depressurization rates to a curve;
h. determining the asphaltene onset pressure of the formation fluid sample from the curve.