Study On The Rock Physics Properties Of Clastic Formation

This dissertation investigated the rock physics properties of Paleogene clastic formation in Jiyang Sag and oils with dissolved gas, and studied the seismic characteristics of reservoirs with different facies, to provide basis for quantitative interpretation of seismic data. For this purpose, 1 carried out following researches using ultrasonic experiment as main tool.First, with 12 oil samples from Shengli and Tahe oilfields, I studied the relationship among ultrasonic velocity or density, pressure, and temperature on 12 dead oils (oils without dissolved gas) and 8 live oils (oils with dissolved gas). The live oil used in experiment is a mixed fluid. A modified model on velocity and density for live oils was presented to account for the errors resulted from existing model (Wang and Batzle model)Second, the effects of effective pressure and lithology on Biot's coefficient and rock elastic moduli were investigated. It is concluded that Biot's coefficient is a power function of normalized porosity, and the exponent is 2/3.Third, on the basis of measurements, 1 generalized Gardner's relation to the form ofρ=CVp~AVs~B, which links Vp, Vs and density, and provides an alternative for Vs estimation.Fourth, the link among sedimentologic properties (diagenesis, rock texture, clay content), reservoir properties (porosity), and rock physics properties (elastic wave velocities, modulus) was analyzed. It shows: (1) The cementing materials is the key factor that effects changes in velocity-porosity plane, (2) rock grain sorting (textural sorting) is the main factor that causes scattering of measurements in velocity- porosity plane, and (3) Clay content affects the velocities of rocks to certain content. The relationship among velocity, porosity and clay content was established.Fifth, the effects of pore fluid and its distribution on seismic properties were studied. According to the experimental data, the sensitivity of different seismic attributes and its combination to pore fluid changes was discussed, and criteria to discriminate oil reservoir were proposed, which provides basis for identification of fluid.Finally, I presented a reservoir prediction method using the seismic attributes optimized by forward modeling. That is, seismic responses to lithology and fluid are modeled by rock physics modeling, the sensitive attributes to lithology and fluid are selected and used to predict reservoir. This method was used to predict the turbidite sand reservoirs in Chenguanzhuang, Dongying Depression, and satisfactory geologic results have been reached.