FEDOROVSKY YU.F.1, KUTYCHKIN B.K.2, MIRZOYAN YU.D.3, KUROCHKIN A.G.3
1Sintezneftegaz LLC, Russia, 2Arcticshelfneftegaz LLC, Russia, 3Ingeovector, Russia

The company «Ingeovector» exists on the market of geophysical services about 10 years and is specialized on carrying out of the borehole observations by the polarized method of vertical seismic profiling (PM VSP).

It offers solutions for wide range of tasks from standard observations of VSP along the vertical stem to the expanded configuration of the observations on nonlongitudinal and level profiles with the object of study of the borehole environment in near field from the stem of investigated well. With the transition from the stem of on well to the whole area of studied object we involve 2D – 3D MCDP materials. We also use the latest prediction technology for the geological cross-section and its oil-and-gas saturation (“Petroseis”).

It is based on the solution of the elastic inversion of seismic transformed data in ?-p region to the characteristics of model as well as absorption and the entropic analysis.

The latest technologies are used for the borehole seismic observations, which allow to get observations in wells with depth to 6m and more:
- digital multi-channel sondes with four-component devices of Galperin construction with twenty four-bits ADC;
- with the temperature in the borehole up to 200 degrees centigrade and the pressure up to 120 atm.

The record of the overall wave field structure is done during the observations PM VSP, it provides the expanded parameterization in the composition:
1) the polarized characteristics of the seismic record structure:

longitudinal (Ap, fp, Vp, Vpm);
transverse (As, fs, Vs, Vsm) and
converted (Aps, fps, Vps, Vpsm) waves;
as well as the polarized characteristics of the cross-section;

2) the elastic constants of the model environment:

K – the bulk modules;
? – the shear modules;
E – the Yong’s modules and others;

3) the complex parameters: ?=Vs/Vp the ratio,

? - the Poisson’s ratio.
The production of the given expanded parameterization allows solving not only the traditional problems of VSP around the borehole environment:
- strati-graphic connection of the seismic boundaries;
- studies of the velocity model of the environment for longitudinal waves;
- stratigraphic connection of the other types of the waves;
- the determination of the velocity model of the medium for transverse and converted waves;
- understanding of the sediment conditions at different stages of the sedimentary cross-section generation on basis of the complex parameters ? – ? in the context of the elastic model;
- selection of the collectors and the determination theirs filtration – capacitive properties taking into account the complex usage of the data of GIH, MTI and the analysis of the core;
- discovering zones of oil-and-gas saturation in the cross-section of the wells and the borehole environment based on the complex of the parameters that have different nature and the realization technology;
- understanding different pressure and stress parameters in the cross-section (not only geostatic, hydrostatic and affective, but also mining pressure, the lateral stress, AHBP, the pressures of the hydrobreak of the bed and others);
- finding mining parameters – Young’s modulus, Poisson’s ratio.

The processing of the 2D – MCDP profiles based on “Petroseis” technology, the entropic analysis and the absorption allows getting space variation of the above parameters within the inspected object. It also gives the possibility to use of suggested complex/analysis for the whole object based on the standard methodology of used parameters and the decision criterions for generated problems.

During the work we carry out the following actions:

1. The complex observations of PM VSP is connected with the data 2D-3D MCDP.
- by vertical profiles;
- by non-longitudinal profiles;
- by level profiles.
The complex of the PM VSP data within an investigated object allows carrying out the space coordinated observation system in internal points of the environment. It provides solutions for the above problems within a borehole environment and within the whole investigated object using MCDP data.

2. The stratigraphic connection of seismic boundaries within investigated environment, not only for longitudinal but also for the other wave types.

3. Studies of the velocity model for the environment, in representing mean and bed velocities as the longitudinal waves and transverse waves.

4. Expanded parameterization of elastic model of the environment based on the full structure of the wave field. It allows determining the relationship between seismic parameters with the properties of petrophysical model of the environment with the usage results from GIH generalization and the obtained multiple regression equations.

5. Evaluation of the stress state of the model in the zone of target depositions to determine the nature of stress distribution, selection of potential collector and the primary trends of migration relative to ascertained catches of different nature. The relation of the oil-and-gas saturation zones with the stress state of the object it is clearly illustrated by the designs of Poisson’s ration distribution – as an indicator of the nature collector saturation of Ovinparm horizon of the bottom Devonian, based on the structure Medinskoe sea 2 and the mining pressure distribution.

6. Differential evaluation of the collector properties within investigated region of the accumulation for different reflection intervals and taking into account their paleosediment conditions during accumulation stage and the following stages of the reconstruction and the diagenetic modifications.

7. Selection of oil-and-gas saturation zones for different stratigraphic cross-section levels and recommended optimal points for well location for best exploration, supplementary exploration and exploitation of the selected accumulation.
The company has carried out many surveys based on a wide range of different function objects from island Sakhalin to the Barents Sea. In both sea and land conditions it has provided qualitative new information about possible oil/gas accumulations.

OIL AND GAS OF ARCTIC SHELF 2008