Geophysical Investigations in Wells Braced with Pipes in the Study of Sections of Oil and Gas Fields

摘要

In geophysical investigations in wells braced with pipes the results are strongly affected by the casing string and the cement ring, which degrades the signal-to-noise ratio. In a number of methods the interference is so strong that no reliable information on sections can be obtained. In view of this, a complex of methods whose application can be useful for obtaining information on geophysical parameters of the formations is considered from the standpoint of shielding the signals from the interfering influence of the casing and the cement ring. In the initial and intermediate phases of the field-exploration stage, repeated investigations, as the most effective way of establishing the positions of gas-oil-water contacts, should necessarily be made in one or more wells. On the basis of such investigations it is also necessary to establish the criteria for finding these contacts from the results of large-scale geophysical work. In the final phase of the exploration stage repeated investigations in unperforated intervals can be carried out to determine the fluid mobilities in individual types of the productive formations whose gas content has been demonstrated by sampling in wells investigated earlier. These investigations may ensure a certain reduction in the volume of sampling work, but the possibility of such a reduction should first be established at a preceding phase in the study of the field. (ERA citation 03:049535)