Differences are compared with the smallest difference accepted and the other differences accepted with a probability (Metropolis Criterion). The model is perturbed and a new model is simulated, and the difference is again measured. Computes difference between seismic and convolutional model with applied wavelet. Simulated Annealing A global optimization technique based on crystal growth in a cooling volcanic melt. The number of traces inverted at once depends on the algorithm. Global More than one trace is inverted at the same time within a common objective function. L1 Norm Misfit measure that is the sum of the absolute data residuals. L2 Norm Most common measure of data misfit, a least squares difference (sum of the square of the data residuals). Objective Function A quantitative measure of the misfit between the observed data and the data predicted by inversion (L1 and L2 Norm). Stochastic (Probabilistic) Inversion A range of equally probable outputs are derived from the input (under controlled number of inputs). Deterministic Inversion A single output value is determined from the input. Absolute Impedance Actual acoustic impedance, contains low frequency trend. Inversion is the flip side of forward modeling.ĥ Common Inversion Terms Relative Impedance Relative changes in inversion, not real values. Inversions can be grouped into categories: pre-stack vs. The more advanced inversion methods attempt to discriminate specifically between lithology, porosity, and fluid effects. The most basic inversion calculates acoustic impedance (density X velocity) of layers from which predictions about lithology and porosity can be made. To determine elastic parameters, the reflectivity from AVO effects must be inverted. The objective of seismic inversion is to convert reflectivity data (interface properties) to layer properties. This overview attempts to summarize the most common terminology and inversion approaches described in the industry.ģ Seismic Inversion Outline Inversion Definition and Terms Required Data Types of Seismic Inversion Role of Inversion Realistic Expectation from Inversion Inversion and New SEC RegulationsĤ What is Inversion? Inversion transforms seismic reflection data into rock and fluid properties. There are numerous combinations, hybrids, and variations of these inversion methods. 1 DHI CONSORTIUM SEISMIC INVERSION OVERVIEW Rocky Roden September 2011Ģ NOTE: Terminology for inversion varies, depending on the different contractors and service providers, emphasis on certain approaches, and the goals to be accomplished.

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