Hydrocarbon Predictions Based On Rock Physical Research And Seismic Porosity Inversion

This dissertation deals with some oil and gas prediction problems related to seismic exploration technologies and petro‐physical theoretic and empirical results with emphasis on calculations of rock matrix and skeleton parameters and seismic inversions based on Biot‐Gassmann equation. The solution of these problems is quite important for applying rock physical empirical results to reduce fuzziness of seismic interpretation and inversion and to increase hydrocarbon prediction reliability. Several main research progresses and innovative methods in rock physics fundamental works and seismic porosity inversion for hydrocarbon prediction are acquired:(1) By petro‐physical modulus measurement and analysis of rock samples which were collected from outcrop rocks and drilling cores in carbonate layers，some basic mechanic and acoustic parameter characterizations and regularities varying with reservoir pressure and temperature of those carbonate samples are obtained. Combining those empirical and research results, we develop a set of technologies and methodologies for carbonate sample’s measurement and analysis that will promote to improve the carbonate reservoir predictions and to set up a new mechanic test software system for carbonate reservoir identifecation.(2) Due to the importance and complexity for calculating rock matrix modulus in fluid‐bearing porosity reservoir，a linear regression method (LRM) for computing this parameter is presented in this dissertation and the LRM relation is derived from reasonable simplifying the Biot‐Gassmann equation and adding a porosity shape parameter in the equation. Comparing with some conventional methods for computing the modulus, the LRM is simple and accurate.(3) Because the formulation of a rock skeleton model and derivation of a useful formula for calculating rock skeleton modulus are very important for wave propagation in two phase material and some existing rock skeleton models and their calculating relations are quite different from each other that will confuse us to apply them correctly, therefor a uniform expression of rock skeleton models and computing formula are requisite. A uniform expression with two adjusting parameters is acquired through analysis and comparison of conventional rock skeleton models and computing formula including Esheby‐Walsh， Pride，Geertsma，Nur， Keys‐Xu，Krief model and formula. By endowing the adjusting parameters with specific values, some unique rock skeleton models with specific physical meaning can be constructed That is an opportunity for us to select most suitable rock skeleton model from real geological and geophysical conditions and to do a reasonable seismic porosity inversion.(4) Based on the modified Biot‐Gassmann equation with a porosity shape parameter and the LRM method for calculating rock matrix modulus as well as the uniform rock skeleton model，a new seismic porosity inversion relation and it’s completion steps are presented. This seismic porosity inversion method is suitable especially for fluid‐bearing reservoir identification in area where distribution of hydrocarbon‐rich strata is controlled by reservoir porosities. The new seismic porosity inversion is also an example of the combination of rock physical research results and seismic inversions.(5) As an example of hydrocarbon prediction and fluid identification we apply seismic porosity inversion associated with rock physical measurement and analysis results to ZJ basin where the existence of an abundant hydrocarbon reservoir is dependent on a middle porosity range that means we can use the seismic porosity inversion’s results to identify oil reservoir and dry or water reservoirs. The seismic real data inversions show that it works quite well.