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AssigneeSchlumberger Technology Corporation
InventorAlberto Malinverno
Estimating the term…
A method of predicting values of formation parameters (e.g., compressional velocity, density, pore pressure, and fracture pressure) as a function of depth includes generating an initial prediction of a profile of the formation parameters and uncertainties associated therewith using information available regarding the formation, obtaining information related to the formation parameters during drilling, and updating the uncertainties as a function of the first prediction and the information obtained in a recursive fashion. Known equations are used for finding initial values, and uncertainties associated therewith are quantified by using probability density functions (PDFs). A Bayesian approach is utilized where “prior PDFs” describe uncertainty prior to obtaining additional information, and “posterior PDFs” account for the additional information acquired. As additional information is acquired while drilling, the posterior PDFs are redefined. Uncertainty in the formation parameters is quantified by sampling posterior PDFs given all the data with a Markov Chain Monte Carlo algorithm which generates numerous formation parameter profiles consistent with the data and the computed Bayesian uncertainties. Histograms of the numerous formation parameter profiles may be plotted to visualize the uncertainty in the formation parameters.
A method of generating information regarding formation parameters as a function of depth, comprising:
An apparatus for generating information regarding a subsurface formation, comprising:
A method for making a decision related to the drilling of a hole in a formation, comprising:
Dependencies are inferred from the claim text.