The given invention refers to the area of the exploration geophysical methods, in particular, the seismic survey of the oil-and-gas deposits on the basis of the complex of waves of the different types. The invention is intended for diagnostics of the reservoir and fluid-saturated properties of the rocks, situated in the vicinity of the borehole. Further diagnostics include the reception of the quantitative estimates of the significant oil-field parameters for the identification of the image of the oil-and-gas deposit, and the subsequent effective baring of the productive layers in the time of exploration and development drilling of the boreholes as well as for the usage of the obtained data for the calculation of the oil and gas reserves.
The method is especially effective for diagnostics of the fissured reservoir (limestones, sandstones) because it allows the measurement of such parameters of the fissured rock as the average length and linear density of fractures, fissured porosity and permeability, fissured residual water saturation and fluid saturation, while the majority of the last cannot be determined with the use of the standard complex of the well logging methods. Besides, the method can be used for the investigation of the lithological and petrophysical parameters of the rocks in situ.
The method of the vibroseism exploration of the oil-and-gas deposits (Ru, U.S. Pat. No. 2,045,079 GO 1V 1/00, 1995) is known, according to which they generate the seismic oscillations with the frequency of (2-20) Hz, register the seismic responses of the earth before and after the excitation of oscillations on three components not less than two geophones simultaneously, and on sharp magnification of the extreme of the received amplitude-frequency characteristics of the seismic response at the frequencies of (2-6) Hz make the decision about the presence of the oil-and-gas deposit. The method allows the detection of the presence of the oil-and-gas deposit in some cases, though its efficiency is not high as far as the amplitude extreme is the parameter depending on the different factors. In particular, the amplitude values essentially depend on the conditions of the excitation and registration, the absence of data about which can give the false information about the presence of the oil-and-gas deposit.
Therefore, for the identification of installation on such the parameter as the amplitude extreme it is necessary to install the level of amplitude discrimination (or threshold), and for the correct choice of the threshold magnitude the additional information on the statistical properties of useful signal and noise is required together with the distribution of probabilities of the amplitudes excess of the useful signal and noise of various levels. The method does not envisage the control over the change of the conditions of the wave generation, and also demands the major expenditures of the time at the usage of additional devices, as existing vibrators cannot generate the seismic waves in the infrasonic range with the required frequency of the oscillations excitations.
The method of the investigation of hydrocarbon deposits on the basis of the effects of their nonideal elasticity is known (Rapoport M. B., Ryzhkov V. I. 1992-2000. Scientific Reports at Intemational Geophysical Conferences of SEG, IGRC, EAGE etc). In the above-mentioned method the experimental fact is used, that the hydrocarbon-saturated porous medium has tall absorption properties. It is supposed, that the effects of seismic nonelasticity of the rocks are shown by means of frequency - dependent absorption and dispersion of the phase velocities of the seismic waves, the values of which are calculated according to the data of the surface and borehole seismic survey. On the basis of method offered by the authors, the investigations of seismic absorbtion according to the surface-seismic survey data (of 2D/3D) were implemented, moreover for the analysis of the absorption parameters the nonstacking seismic data and traceability of the seismic reflections on the time cross sections were used. The received values of the absorption parameters are used as the indicators of the hydrocarbon presence in the surface seismic survey. The vertical seismic profiling (VSP) data in the productive boreholes are regarded as parametric at the analysis of seismic nonelasticity and are applied for the separation of the productive thicknesses skipped in the time of well logging, while the borehole observations of VSP, the abnormality absorption parameters and velocity dispersions received by the surface seismic survey, are immediately connected with the oil-and-gas deposits. For the definition of the threshold level, which corresponds to the outline of the deposit, the values of the indicator parameters are calibrated permanently over the results of the tests of the productive boreholes. The usage of the given method allows to define the most perspective in the oil-and-gas-bearing relations of the investigated area, and at the presence of the boreholes also allows to delineate the productive sections.
However, the above-mentioned method uses as calculated of the surface seismic survey data and includes the condition of the mandatory adapting of the investigation results with the well logging data. Because of lapses in the time of parametric measurement and in the presence only the effective attenuations estimates of the amplitudes method can give the erroneous prognosis concerning the discovery of layers promising in the oil-and-gas-bearing relation.
Most close according to the technical essence to the declared invention is “A method of the determination of the theological properties of solid-liquid mediums by means of the multiwave borehole seismic survey” (UA, patent No 718 C1 G O1 V 1/40, G 01 V 1/00. 15.12.93. Bull. No 2), implementing the principles of borehole seismic survey (prototype). The essence of the invention consists in the following. In the vicinity of the borehole the plane longitudinal wave is formed by means of the seismic oscillations excitation by the near-surface sources. By means of the three-component geophones of the displacements (or stresses) the dynamical characteristics of the direct seismic waves in the investigated borehole are recorded, at the same time one of the geophones is oriented along the normal line to the plane wavefront of the longitudinal wave. Then, according to the received kinematic characteristics of the longitudinal and shear (or converted) waves the numeral processing of the dynamical characteristics of the direct longitudinal wave is fulfilled. For this purpose they execute the separation of the monotype time signals for the registered borehole components of displacements (or stresses) by pointwise deduction out of the axial component (z-component component) and the tangential component (x,y-components) of the displacements (or stresses) with the obtaining of the significant parametric estimates of the separate signals in the future.
After that according to the known analytical relationships the kinematic and dynamical parameters are transformed in respect to the bedded values with the further determination of the theological parameters of the rocks, as well as the absorption parameters of the longitudinal wave for each observation point along the depth of the borehole. The known method of the borehole seismic survey allows over the dynamical characteristics of the direct (downgoing) seismic waves to define the theological and absorption parameters in porous - fissured layers, which are opened by means of the exploration borehole, and in view of the essential differentiation of the oil-and-gas deposits over rheological properties the reliable information about the physico-mechanical parameters of the rocks in the vicinity of the borehole is received.
However, the above-mentioned method ignores the conditions changes at the multiple excitation of the oscillations by the near-surface sources and the influence of the specified changes on the dynamical parameters of longitudinal wave. The method also does not envisage the statistical processing of the amplitude values of the monotype time signals for the receiving of the coefficients of attenuation and energy dispersion of longitudinal wave. The ultimate aim of the known method does not allow to receive the bedded values of the oil-field parameters for the exact identification of the oil-and-gas deposits images.
The kernel of the problem which advantaged the creation of the present invention, consists in the following. The features of the existing technology of the deep borehole drilling with the considerable differentiation of bedded pressures in the rocks along depth of the borehole is demanded in order the above-mentioned drilling mud heavers will be applied under the specified conditions for the prevention of emergencies, therefore, there is the peening of the part of perspective in the oil-and-gas-bearing relation layers. By the appearance of the drilling mud in last considerable invaded zones qualitative diagnostics of the productive layers by means of the standard methods of the well logging becomes ineffective, and the time of the deposit development leads to the skip of the average-and-low-permeable oil-and-gas-bearing layers and decreases the potential productivity of the boreholes in (1.2-1.5) times.
The task, set at making the given invention, is to receive the method of wave diagnostics of the oil-and-gas deposit which by means of the seismic insonification of the vicinity of the borehole will allow over the recording of the displacement vector data in the investigated borehole by means of the three-component seismic profiling to receive the oil-field information on the values of the absorption coefficients, characterizing the type of the fluid saturation; the coefficients of fissuring, granular and fissured permeability, residual water saturation and fluid saturation of the rocks, including the layers with the considerable invaded zone of the drilling mud.
The existing problem of transition from the observable values of the parameters to their bedded values can be solved by the data special processing, introducing the corrections to the dynamical parameters of the borehole and check data, taking into account the changes of the conditions of the wave excitation and the filtrational effect of the covering thickness of the rocks for each observation point along depth of the investigated borehole.
Last allows first to calculate the dynamical parameters of the impulse responses of the layers, and then to transform their corresponding petrophysical and oil-field parameters and simultaneously provides the reception of the reliable information about the effective thickness of the productive layers and about sites of the gas-oil-water contacts, and also enables to estimate the quality of the cap rocks and to establish the presence of the tectonic dislocations of the investigated borehole of crossing.