Assessment of Local Productivity in Hydrocarbon Reservoirs by Recording Seismic Background Noise: Statistical Straggling and Reliability Improvement

The author resolves the problem connected with reliability improvement of full-scale investigation data by the method of remote productivity assessment in a hydrocarbon reservoir using records of seismic background noise on ground surface. The complication is a high-amplitude broadband interference covering half a service band. On the basis of a polyspectrum analysis, a remote oil content assessment, different from the earlier proposed method, is proposed. The procedures of statistical straggling and averaging in multi-point recording are discussed. A good agreement of the results of two independent methods increases reliability of total thickness estimates in productive intervals under a recording point. This elevates robustness of oil and gas exploration and facilitates selection of promising drilling sites. In a general case, it is possible to use half-sums of estimates of the two methods. In the areas without wells drilled, productivity maps are calculated in arbitrary units; when the thickness of productive intervals is measured in a number of wells, using a coefficient of linear regression facilitates transition from arbitrary units to units of length.