Downhole Gas-Oil Ratio Estimation via Chemometric Sound Speed Correlation
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Solution Overview
Problem
Current methods, such as the Batzle and Wang relations, are unable to algebraically solve for gas-oil ratios (GOR) downhole using measurable parameters like sound speed and live oil density due to their complexity, limiting practical utility in hydrocarbon exploration and production.
Innovation Solution
A chemometric approach is employed to derive correlation equations through a synthetic training set, using measurable downhole properties like sound speed, pressure, and temperature to estimate GOR, leveraging chemometric analysis and regression methods to approximate relationships between input and output parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Batzle and Wang relations are used to estimate GOR, then the theoretical framework is comprehensive, but the equations cannot be algebraically solved for GOR using measurable downhole parameters due to their complexity
Solution Approach 1:
The patent creates a simplified copy of the complex Batzle and Wang equations by developing a new correlation equation that replicates their predictive capability while being algebraically solvable. The new equation copies the essential relationships between GOR, sound speed, density, pressure, and temperature without inheriting the unsolvable complexity of the original system.
Solution Approach 2:
The patent replaces the mechanical algebraic solution approach with a chemometric methodology. Instead of attempting to algebraically manipulate the complex equations, the invention uses statistical correlation and regression analysis to establish a practical relationship between measurable parameters and GOR, substituting mathematical mechanics with statistical methods.
2Ease of operation
If traditional methods are used, then the theoretical models are available, but they cannot provide practical downhole GOR values due to requiring non-measurable parameters like stock tank oil density
Solution Approach 1:
The patent fundamentally changes the parameter set from theoretical to practical by replacing non-measurable parameters (stock tank oil density, formation volume factor) with measurable downhole parameters (sound speed, live oil density, pressure, temperature). This parameter transformation enables direct field application without requiring laboratory analysis or multiple sequential measurements.
Solution Approach 2:
The patent extracts and removes the problematic non-measurable parameters from the equation system. By eliminating stock tank oil density and formation volume factor from the final correlation, the invention creates a self-contained equation using only directly measurable downhole parameters, thereby improving practical utility.
3Ease of operation
If chemometric analysis is used to derive correlation equations, then GOR can be estimated using measurable parameters, but a synthetic training set and regression analysis are required
Solution Approach 1:
The patent performs preliminary chemometric analysis and regression modeling to establish the correlation equation before field application. By pre-processing the data and determining the optimal relationship between parameters during the development phase, the invention eliminates the need for complex real-time calculations during downhole operations, simplifying practical deployment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the estimation of GOR downhole using non-optical measurements, achieving high correlation coefficients and overcoming the limitations of existing techniques by providing a feasible methodology for characterizing fluid properties in hydrocarbon formations.
Implementation Method 1
receiving at least one input signal representing sound speed of a fluid downhole
Data Source
AI summary
A method for characterizing a desired property of a fluid downhole is described. In some non-limiting examples, the method comprises receiving an input signal representing sound speed of a fluid downhole, processing the input signal using a correlation equation expressing the desired property in terms of at least sound speed to produce an output signal representing the desired property, and outputting the output signal. In some examples, the correlation equation is derived through a chemometric analysis of a training data set, the training data set comprises a plurality of input values and a plurality of output values derived from said input values, between the desired fluid property and the first measured property, and the output values are calculated from the input values using a series of correlation equations. In at least one example, the desired property is gas oil ratio. In another example, the desired property is gas brine ratio. In a further example, the series of correlation equations comprises the Batzle and Wang relations. In another example, the receiving comprises receiving a plurality of input signals representing a plurality of measured properties of a fluid downhole and the processing comprises processing the plurality of input signals using the correlation equation expressing the desired property in terms of the plurality of measured properties.