Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
2003-03-31
2004-11-09
McElheny, Jr., Donald (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
Reexamination Certificate
active
06816787
ABSTRACT:
BACKGROUND OF THE INVENTION
The subject matter of the present invention relates to a method and apparatus for generating and displaying a virtual core analogous to a sample of a portion of the Earth formation which might be retrieved from a formation during the drilling of a wellbore (called a core), for generating and displaying a virtual plug analogous to a sample (called a plug) obtained from the core that might be retrieved from the formation during the drilling of the wellbore, and for saving/archiving one or more interactions which may be performed in connection with the virtual core.
A core is a cylindrical piece of rock that is acquired during the drilling of the wellbore. This core will be referenced as the solid core to distinguish it from the virtual core. Several measurements are made on the core which address the evaluation of the formation, and information from those measurements are incorporated into the studies of various discipline groups. Oil companies also acquire measurements, known as well logging measurements, in the wellbore of the rock formations surrounding the wellbore. If these same measurements (such as well logging measurements) could be used to describe the rock and present the rock in the form of a virtual core, data from the previous measurements (such as well logging measurements) could be translated into a form analogous to measurements performed on a solid core. Recall that the client or customer might already obtain measurements on a solid core. Therefore, if the customer has a virtual core, that customer could immediately compare any received virtual core information (which has been given to him by the subject company and represents well logging measurements) with his own measurements on the solid core and then utilize the results of that comparison to validate/calibrate the characterization of the reservoir or Earth formation located adjacent to the solid core. Therefore, the virtual core is a way of characterizing the reservoir in terms with which the customer is already familiar. The solid core permits characterization of the formation on the scale of a few centimeters. To be comparable, use of the log information is needed to describe the formation as a virtual core to similar resolution. Today, some measurements can be made on the formation at the borehole wall and placed in the form of an image that provides a spatial resolution in the order of centimeters. Other measurements can be made on the formation and recorded in the form of a log. These, typically, provide an average value at each depth in the borehole and have a spatial resolution from a few centimeters to several feet. If all such measurements can be combined, it may be possible to describe the rock on a scale similar to those on the solid core. However, such a description will be in a continuous, digital form. By using the virtual core, all aspects of the rock are available in response to the touch of a button.
In addition, some present day systems make measurements on an earth formation utilizing a well-logging tool to generate a well-log and then determine certain rock parameters from the obtained well-log, such as porosity, permeability, oil space, saturation. The log, which is a measurement of the earth formation extending outwardly from the borehole wall, can be used to create a virtual core, which is a description of the Earth formation disposed at the surface of the borehole wall. In addition, the customer extracts a piece, called a plug, from the formation rock in the solid core and he makes the same measurements on the plug, which is, typically, about one-inch diameter by one-inch long. Petrophysical properties (such as porosity, for example) measured from the plug are routinely compared to that measured from the log. Without cutting the entire one and one half feet of rock into several plugs and then averaging the measurements, incomplete and sometimes inaccurate comparisons are made. Having the aforementioned digital continuous description of a virtual core, if software could be utilized to select a corresponding point on the virtual core, then average the properties over an inch, both cylindrically and longitudinally, around the selected point, in effect, an estimate is made of the petrophysical property over similar volumes. If it is known in which direction a solid plug is taken, or the depth at which the solid plug is sampled, and if a virtual plug of the virtual core is made at the same depth and the same direction, an accurate comparison can be made.
With the solid core, information can be extracted over only one short piece of the entire length of the wellbore. Therefore, assuming possession of only one short piece of a solid core, if it is confirmed that the short piece of solid core matches a corresponding short piece of the virtual core, then a higher confidence exists that all other short pieces of solid core, if obtained, along the entire length of the wellbore would also match all other corresponding short pieces of the virtual core.
Having the formation properties captured in the form of a Virtual Core in digital format enables several computations to be interactively performed by the customer to simulate different scenarios. For example, an average of certain properties over specified formation intervals may be determined. This enables computation of the volumes of several fluids that are present in a reservoir thereby enabling an improved evaluation of the reservoir's commercial value. In addition, simulations may be made of several different completion and production scenarios. From these simulations, a preferred scenario may be selected for a specific implementation that best matches the objectives for the well. The results of any or all of the above such interactions needs to be captured and the virtual core provides for a digital means to do this. Hence, the Virtual Core remains a current archive of our knowledge of the formation properties at a well and of our use of such knowledge in the shaping of reservoir management decisions.
SUMMARY OF THE INVENTION
An aspect of the present invention includes a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine, to perform method steps for generating a compilation of formation property data as a function of depth and azimuth in a wellbore, the method steps comprising: creating, in response to an integrated formation evaluation which includes one or more physical measurements as functions of depth in a wellbore and one or more formation properties as functions of depth in a wellbore and a facies log measurement as a function of depth in the wellbore and an image as a function of depth and azimuth in the wellbore of a physical measurement, a representation of the physical measurements and formation properties as functions of depth and azimuth in the wellbore on the condition that the each of the physical measurements and each of the formation properties as a function of depth in the wellbore can be related to the physical measurement in the image; and combining the physical measurement image as a function of depth and azimuth in the wellbore with the facies log measurement as a function of depth in the wellbore thereby generating a facies image as a function of depth and azimuth in the wellbore and determining a representation of any formation property as a function of depth and azimuth in the wellbore corresponding to the facies image on the condition that the formation property cannot be related to the physical measurement image.
A further aspect of the present invention includes a method of generating a compilation of formation property data as a function of depth and azimuth in a wellbore, the method comprising: creating, in response to an integrated formation evaluation which includes one or more physical measurements as functions of depth in a wellbore and one or more formation properties as functions of depth in a wellbore and a facies log measurement as a function of depth in the wellbore and an image as a function of depth an
Essawi Amr
Gibson William Dean
Ramamoorthy Raghu
Srivastava Ashok
Echols Brigitte L.
McElheny Jr. Donald
McEnaney Kevin P.
Ryberg John J.
Schlumberger Technology Corporation
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