Reservoir Seismic Responses Based On Experimental Rockphysics

With the increasing complexity of the exploration targets and exploration technologyadvances, more and more oil fields are going to explorate and develop subtle reservoir. Tolearn more about the seismic response of subtle reservoirs and to make reservoir parametersas well as seismic parameters more closely, using rockphysics as a link is necessary, in whichthe wave velocity is a very important parameter. In this paper, some rockphysics expermentstested the wave velocity on88samples under dry and saturated conditions. The experimentalrelationship is reasearched in the paper, which is between pressure, porosity, elastic modulusand wave velocity, and the difference between static and dynamic modulus of those rocksamples.Shear wave velocity is a parameter that geophysicists always want to obtain and isessential in AVO forward modelling. For this, the method of calculating shear velocity basedon experimental rockphysics is developed. Firstly, using the relation between wave velocityand the moduli of rock constituents, rockphysics model is bulit. Then, the bulk and shearmoduli of minerals are inversed by simulated annealing algorithm to calculate shear velocity.Practical application shows that the inversion result is reliable and the error is small. On thisbasis, the replacement of reservoir fluid and the AVO forward modeling are achieved. Aboveachievements offer some basic data to predict the properties of rock and fluid, which canefficiently reduce the uncertainty and ambiguity of seismic interpretation.At the complex surface and tectonic region, the seismic forward technology can get morecomplete seismic wave field, which can be compare with the mechanism of the wave as wellas the kinematics and dynamics characteristics of seismic records. For reservoirs, theseismic forward technology can get the post-stack and before-stack seismic wave field whichhaven’t be polluted by noise. So it can provide theoretical evidence for the reservoirinterpretation. Because of the deep-seated Donghe sandstone is very thin, the seismicresponse of Donghe sandstone is unclear as well as it’s pinchout and trap are difficult toidentify. In the paper, the wave equation finite-difference variable grid numerical simulationwhich realized the unity of the accuracy and efficiency is used to study the seismic responsecharacteristics of Donghe sandstone in the Tarim Basin.Before using the forward modeling technique in the study of Donghe sandstone, it must firstly master the seismic reflectance signatures and the distributing rules.Through theanalysis of geological information, seismic and well log data, the15simple theoretical andpractical forward models of single well have been built. In the peper the seismic responsecharacteristics are comprehensively analysed, of which Donghe sandstone by combining theresult of forward modeling and their snapshots. Subsequently, by the research of geologicalinformation, the5actual well seismic profiles are used to built macro-model which havedifferent blocks and lithology. Then, in the paper the seismic response forward characteristicsare analysed, of which the Donghe sandstone pinchout basing on the result of forwardmodeling, and summarizes some propagation rules which have some theoretical sense. At last,solid theory basis for the deep-seated reservoirs prediction is provided in the peper.