A new searching technology of retained oil, not covered with a drainage in oil deposits, during their development using any waterflood system, by a method of various amplitudes crosswell seismology of productive formations in the crosswell space, on late and closing stages of development is proposed and services for production works, processing and interpreting of the received data with producing of determinations and recommendations are offered.
The technology provides a prediction and geological commercial evaluation of retained oil with applicable determination integrity of the following exploration field problems:
- Indication of retained oil and mapping it along the horizontal deposit;
- Calculation of recoverable residual oil reserves from the retained oil deposits;
- Design of additional producting wells, including control horizontal wells with a lateral kickoff;
- Operational supervision of oil fields on the late and closing stages of development.
The technology is realized by using a hardware and methodical complex that includes AMC-VSP-3-48 bore-hole multi-module digital three-component seismic equipment, downhole blasting seismic source on the basis of an explosive detonating cord of DShTV type with explosive weight from 10 to 100 g and a set of programs for processing of the obtained results. At the same time for the choice and verification of a seismogeological model of interhole space data of the standard well logging complex, laboratory petrophysical researches of core and field data about permeability and fluid content of producing formations and oil viscosity are used.
The surface equipment includes an onboard personal computer (PC) with controller of digital telemetry communication line, providing control over operating regime of seismic probes and information acquisition along logging cable. The second lift is used for run blasting seismic source in a nearby well. The suggested technology allows the use of non-blasting downhole seismic sources with a changeable energy in pulse of 5 ÷ 25 kJ.
Economic benefit of the technology is achieved due to involvement in the development of immovable oil in solid in the interwell space, which isn’t covered by oil extraction. These current reserves can reach up to 20% of the estimated oil reserves on the oil fields in a closing stage of development. The offered technology can be also effectively used for process monitoring of oil fields at the late and closing stages of their development.
Lithological and acoustic section of crosswell shooting No.2446 and No.2466 wells of Tuimazy field
P-wave seismic data set from detonation of explosive material with weight 41, 58, 76 and 93 gr. in the reservoirs: a)compact limestone; b)oil-saturated; c)sandstone
Spectra of longitudinal waves depending on weight of explosive material in the reservoirs: a)watered sandstone; b) oil-saturated sandstone; c)compact limestone
Velocity decrement diagrams of longitudinal waves ΔVp1, ΔVp2 and ΔVp3 in case of increase the weight of explosive material in the reservoir according to a compact limestone, oil-saturated and watered sandstone