Method for in-situ analysis of formation parameters
AssigneeBaker Hughes Incorporated
InventorsSven Krueger, Eick Niemeyer, Matthias Meister
Life of this patent
Estimating the term…
Abstract
A method of performing a formation rate analysis from pressure and formation flow rate data. Pressure and flow rate data are measured as fluid is withdrawn from a formation. Variable system volume is accounted for. The pressure and flow rate data are correlated using a multiple linear regression technique. Time derivative terms related to pressure and flow rate are smoothed using a summation technique, thereby providing better correlations than using the time derivatives directly. Formation parameters comprising formation permeability, formation pressure, and fluid compressibility may be determined from the correlation.
Claims16
A method of determining at least one formation parameter of interest, comprising;
- a. sampling fluid from a formation using a tool having a sample chamber and a fluid sampling device;
- b. determining time dependent pressure in a corresponding time dependent tool volume;
- c. determining a corresponding draw rate of the formation fluid as a function of time;
- and
- d. using a sum of said tool volume pressure, a sum of a time derivative of said tool volume pressure, and a sum of said draw rate as input data for a regression analysis wherein, the output of the regression analysis represents the at least one formation parameter of interest.
A method for determining at least one parameter of interest of a formation surrounding a borehole, the method comprising:
- a. conveying a tool into a borehole, the borehole traversing a subterranean formation containing formation fluid under pressure;
- b. extending a probe from said tool to said formation establishing hydraulic communication between said formation and a volume of a chamber in said tool;
- c. withdrawing fluid from said formation by increasing the volume of the chamber in said tool with a volume control device;
- d. measuring a pressure of said fluid and the corresponding volume of said chamber as a function of time at a plurality of times generating a data set of pressure and volume at each of said plurality of times;
- e. calculating corresponding time derivatives of said measured pressure and said measured volume for each of said plurality of times;
- f. generating a set of equations comprising a multiple linear equation for each data set relating said measured pressure to a first term related to the time derivative of pressure and a second term related to the time derivative of volume, where, for each data set;
- said measured pressure comprises said corresponding measured pressure added to the sum of measured pressure of all preceding data sets;
- said first term comprises said corresponding time derivative of pressure added to the sum of time derivatives of pressure of all preceding data sets;
- and said second term comprises said corresponding time derivative of volume added to the sum of time derivatives of volume of all preceding data sets;
- and
- g. performing a multiple linear regression on said set of equations determining an intercept term, a first slope term associated with said first term, and a second slope term associated with said second term.
Dependencies are inferred from the claim text.