Method and apparatus for estimating of fluid contamination downhole
AssigneeBaker Hughes Incorporated
InventorsRocco DiFoggio, Bernardo Pohl
Life of this patent
Estimating the term…
Abstract
The present invention provides method and apparatus for quantifying sample clean up in real time by providing curve-fitting measurements of optical or other physical properties of fluid downhole. Fluid is extracted from the formation surrounding a borehole. As fluid continues to be extracted the composition of the extracted fluid changes, altering the measured values of optical and physical properties of the fluid. Measurements are made of optical or physical properties of the sampled fluid, analysis is performed on the acquired measured data points.
Claims19
A method for estimating a parameter of formation fluid downhole, comprising:
- extracting the fluid from a formation;
- making a plurality of measurements for a property, A, of the fluid;
- fitting a non-asymptotic curve to the plurality of measurements;
- taking a first derivative of the fitted curve;
- and
- selecting a terminal value of the property, A0, that produces a best fit between y and x, wherein y=A at time t minus the terminal value, A0, and x=t(dA/dt) at time, t;
- and
- estimating the parameter of the formation fluid using the best fit between y and x.
An apparatus for use downhole, comprising:
- a probe for receiving a fluid from a formation;
- an optical sensor that makes a plurality of measurements of an optical property, A, of the fluid;
- and
- a processor configured to (i) fit the plurality of measurements of the optical property of the fluid to a non-asymptotic curve;
- (ii) take a first derivative of the fitted curve, and (iii) use one or more values of a terminal value of the optical property A0, to produce a best fit between y and x, where y=the optical property, A, at time t, minus the terminal value, A0, and x=t(dA/dt), at time t, and (iv) estimate a parameter of the formation fluid using the best fit between y and x.
A computer-readable-medium containing instructions that when executed by a computer perform a method for estimating formation fluid contamination downhole, comprising:
- extracting the fluid from a formation;
- making a plurality of measurements for a property, A, of the fluid over time;
- and
- fitting a non-asymptotic curve to the plurality of measurements of the property of the fluid;
- taking a first derivative of the fitted curve;
- using a terminal value of the property, Ao, to produce a best fit between y and x, wherein y=A, at time t, minus the terminal value, A0, and x=t(dA/dt), and t=time;
- and
- estimating the formation fluid contamination at time, t, from the best fit between y and x.
Dependencies are inferred from the claim text.