On The Application Of Earth Q-absorption In Seismic Exploration

High-resolution and high-fidelity seismic data and strata attributes to delineate exploration targets are highly demanded in nowadays petroleum exploration. Compared with conventional resolution-enhancement processing techniques, Q-absorption has characteristics such as much looser assumptions on input data etc. and thus possesses advantages in resolution-enhancement and signal-preservation. For this reason,“Application of Earth Q-absorption in Seismic Exploration”was chosen as the main subject of this study and seismic data Q-absorption compensation was mainly focused on.The relevant existing works on earth Q-absorption was first outlined and the key concepts of relevant disciplines, the main contents and research lines of, and the ways to deduce the theories on earth Q-absorption were also done to make the necessary concepts and basic theories ready for this study.Since the current issues in the application of earth Q-absorption in seismic exploration fall approximately in three categories,‘techniques’,‘insights or understanding’and‘strategies’, this study was oriented accordingly. Through field experiments, laboratory experiments and in-house data processing and intensive analysis, this study obtained the following main results.On techniques:①a Q-estimation technique called‘Spectrum-Constrained Q-estimation’was developed to reduce the affects of reflectivity.②a method to estimate dispersion-caused time delays was put forward.③a gain-control method for amplitude compensation was proposed that better suits the frequency-variant S/N ratio property of input data.④a suite of techniques including‘Q-estimation’,‘earth Q-model building’, and‘Q-compensation’were developed in a large seismic software system and good application results were obtained. On insights:①the major affect of weathering layer on seismic data is not Q-absorption, rather source coupling or receiver coupling difference or LWL-related noise contamination.②source coupling and receiver coupling caused data differences are generally the main disturbances to near-surface Q-estimation, and they are easy, and thus often, to be mistaken for Q-absorption effects.③wet sands have stronger Q-absorption effects than dry ones on seismic waves and the existing Q-absorption model is probably improper for describing loose near-surface materials.④a detailed criteria and procedure for compensation result evaluation and a detailed application processing flow were presented to obtain optimal Q-compensation application results.On strategies:①a strategy to use surface reflections for near-face Q-estimation was proposed to avoid coupling disturbances and its ability was approved through application.②a strategy for compensation parameter or compensation result evaluation was brought forward.