METHOD PREDICTING DEVELOPMENT ZONES OF SECONDARY FRACTURE-TYPE RESERVOIRS IN SEDIMENTARY SECTION

摘要

FIELD: physics; geophysics.;SUBSTANCE: invention relates to geology and can be used to predict development zones of secondary fracture-type reservoirs in a sedimentary section. The method involves detecting reflected seismic waves associated with a selected system of deposits; performing lithologic-petrophysical investigation of rock samples to determine the most probable genesis of secondary reservoirs; selecting lithotypes on which secondary fracture-type reservoirs are formed; drilling a well in anticline structures and determining the depth of occurrence of fold hinges, morphologic parameters of the structures, including maximum seam contortion, width, length, area and intensity of folding; using downhole logging results to determine secondary porosity; measuring formation pressure in test intervals; establishing a critical value of secondary porosity Kpvt^cr; establishing a multidimensional correlation relationship of the secondary porosity Kpvt=f(i, gradp, J, Kpob, H), where i is the maximum seam contortion; gradp is the gradient of formation pressure; J=i/S is folding intensity; S is the surface area of the structure; Kpob is the overall porosity; H is the depth of occurrence of fold hinge; performing detailed field seismic survey on unstudied areas of the territory with a dense seismic grid through not more than 100 m; processing field seismic materials; detecting presence of anticline structures and deep faults; constructing seismic-geologic profiles along and across the detected structures; determining the depth of occurrence of vfold hinges and morphologic parameters of the structures; using the established relationship Kpob=f(H) to determine overall porosity at the depth of occurrence of the bedrock on newly detected structures; determining the predicted gradient of formation pressure; using the established multidimensional correlation relationship of secondary porosity Kpvt=f(i, gradp, J, Kpob, H) to predict the value of Kpvt; comparing Kpvt with the lower limit of Kpvt^cr for the "reservoir-nonreservoir" boundary, which is then used to predict the probability of development of secondary fracture-type reservoirs, the expediency of drilling on said structures and the well drilling procedure. If Kpvt/Kpvt^cr1.2, it is expedient to drill on a profile of three dependent wells; if Kpvt/Kpvt^cr=(0.7-1.2), drilling only one well in the crest of the structure is expedient.;EFFECT: high efficiency of prediction.;1 dwg, 5 tbl