English Français Español Русский 中文 Deutsch Português عربي italiano 日本



         INTERGEO



 Home  Service  Software  Documentation  Contacts

Treating VSP

Solution of the following primary goals is envisioned:
- Learning of features of a wave seismic field with emphasis of attention to kinematic and dynamic features longitudinal a straight line and back waves – as basic type of beneficial waves;
-Studying of the high-speed performance of the cut-away, including definition of mean, sheet and interval rate of propagations in a vertical cut-away longitudinal and transverse waves;
- Constructing time and depth profiles VSP of SPEECHES on longitudinal and exchange back waves.

THE METHOD OF AStationLICATION OF TREATING OF MATERIALS VSP

3.1. Evaluation test of fundamental materials

The visual record analysis is put in an appraisal ground the basic – vertical reductants with near and removed Shot. It is noticed that on both seismograms below a conductor part (from depth ~ 250m) up to a stope back the forward longitudinal wave is continuously traced, and in the subsequent part of record (in the same spacing) lines of correlation of variety of reflexes, including from boundaries of target value are almost continuously correlated. From the noted follows that records Z-components from both Shots provide absolutely reliable solution of the primary goals of the geologic task:
- Learning of high-speed model of a cut-away;
- Conducting of a stratigraphic control of reflexes;
- Time section constructing on longitudinal waves.
The high extent of a contamination of record by surges-hindrances in a conductor part of the profile, linked to casing 'ring' will not prevent confident solution of the enumerated problems; their influencing will affect only insignificant reduction of length of a time section.
At the initial stage of treating record horizontal X-, Y- a reductant with ПВ1 and ПВ2 has been reproduced. On these not polarised records the forward cross SV-wave and cross components of exchange back waves are quite well dedicated and traced. Meliorating trace these surges will allow to make definition of high-speed arguments of transverse waves and time section constructing on exchange back waves.
On records of audit seismic detectors real times of a straight line and the longitudinal waves refracted from small boundaries are snapped quite.
The materials introduced on treating as a whole on quality merit a good appraisal.
The customer introduces indispensable materials for data interpretation VSP To them are referred: a time section on a profile driving through a hole, LOG data, stratum breakdowns. Claims to these materials are not present.

3.2. The method of application of treating of materials VSP

 All process of treating can be partitioned on four stages: pretreatment, the basic data processing longitudinal and not longitudinal VSP and special treating (fig. 3.1). In order to avoid bulkiness of an illustration of routines we are confined to reduction of a minimum of the drawings to the greatest degree directly related to the basic results of treating.                                       

PRELIMINARY PROCESSING
THE BASIC PROCESSING LONGITUDINAL VSP THE BASIC PROCESSING NOT LONGITUDINAL VSP
ADDITIONAL (SPECIAL) PROCESSING
Fig. 3.1 General scheme of stages of processing  

 


3.2.1. The count of pretreatment

The primary goal of a predesign stage – obtaining of summary seismograms from field records VSP, the greatest possible increase of the relation of a cue to a clutter, transforming of field seismograms to a format of handling system for performance of the further treating.
The count of pretreatment begins with input of field materials in a programmatic complex and definitions characteristics each trace (editing of traces). As at one record there are the traces filed from ground-level and borehole recipients, at a following stage of treating apply demultiplexing - separation of communal record into fields of audit geophones and single-component geophones with the subsequent obtaining of single-component seismograms VSP.

DATA INPUT
TRACES EDITING
DEMULTIPLEXING
CALCULATION OF STATIC CORRECTIONS
CORRELATION OF THE FIRST BREAKS
THE ESTIMATION OF DATA QUALITY
REMOVAL OF HINDRANCES MUTE, FILTERS
THE ESTIMATION OF DATA QUALITY
  The main feature of this calculation and input routines stat. correction VSP their attachment to number of detonating and, accordingly, only to a part of traces of communal record is. stat. correction are calculated under the formula: Δtst. = ti – t1, where ti – i-a trace of a primary arrival of an audit geophone (joint venture) from the maiden detonating, and t1 – the trace which has been taken over for bearing.
Fig. 3.2 Preliminary processing. Structure of procedures  

At correlation of primary arrivals of a forward longitudinal wave the extent of their stability on a recording format and tracing is instituted, and preconditions to correct conducting of some routines (a tentative estimation of a proportion a cue/noise, calculation of high-speed arguments etc.) are valued.
At a pre-award stage polarising treating in which one result record nondirectional on Shot horizontal a reductant and vertical reductants are translated in peephole reference system PRT [3] is carried out. PRT [3]. In this case the direction of fulcrums of responsiveness a reductant coincides with a total vector of oscillatings and records longitudinal, cross and alternating waves get the most expressed peak nature.
On fig. 3.3 and 3.4 seismograms before polarising treating are demonstrated. Results of last are resulted only for horizontal a reductant. On vertical a reductant this routine does not produce some substantial improvements.
3.2.2. The count of basic treating VSP

The count of the basic treating engages the routines demonstrated on fig. 3.5. The basic treating begins with treating of observations on a longitudinal profile. Two primary goals which one are routinely put before VSP thus dare: definition of high-speed arguments of environment and conducting of a stratigraphic control of back waves.

XYZ before processing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R-component

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

STUDYING OF HIGH-SPEED CHARACTERISTICS OF ENVIRONMENT
STUDYING DYNAMIC
ALLOCATION OF THE FIELD OF TARGET WAVES
REDUCTION OF THE FIELD OF TARGET WAVES TO THE VERTICAL
ASSEMBLY DIAGRAM CONSTRUCTION
Definition of the high-speed arguments engaging mean Vmean, sheet Vsh., interval Vint. velocities is carried out on a first-arrival curve of a straight longitudinal wave; in case of slant well profiling the produced directional surveys are allowed.
Design values of velocities, and also functional link of times and depths on a first-arrival curve of a straight longitudinal wave are brought in tables for their subsequent use at data processing of ground-level seismotrial operations.  
Fig. 3.5 Basic processing longitudinal a VSP. Structure of procedures

Similar definitions are carried out for transverse waves which one phase hodograph is traced in later events. At use of its magnitude of high-speed arguments have relative nature, and for a finding of absolute values it is necessary to enter the correction into a phase hodograph for primary arrivals.
Indispensable analysis stage of seismograms VSP is learning of dynamic performances of target surges: forms of surges and their spectral properties. The first-arrival time is with that end in view set and curvilinear averaging of traces in the range of one-two wave periods is held. The problem of correct interpretation of a wave pattern most effectively dares with attraction of multidimensional spectral analysis.
All-important problem of the basic treating is the problem of separation of target surges from record, in a strong extent clogged with clutters of regular and irregular nature. Separation process leans against result of the analysis of dynamic and kinematic arguments and is reduced to application of the routines directed on repressing of surges-hindrances and surges auxiliary reductant. Various types of one-dimensional screens are referred to anti-aliasing routines: low frequency, notch, strip, harmonic, etc. At repressing of stirring (auxiliary) surges use routines of deduction and existential filtering.
At the heart of algorithms of subtraction the principle of learning kinematic and dynamic performances of stirring surges, modelling of their field and its subtraction from record of seismograms lies.
Methods of existential filtering use the information on distinction of frequency composition, and also apparent velocities of target and stirring surges. The complex of methods of the treating is applied to separation of beneficial surges, engaging kinematic transformings and various types of filterings.
At problem solving, «removal of multiple surges» and «increase of frequency response curves», is used predictive deconvolution (the operative is counted on an incidenting wave).
Results of application of the enumerated routines are introduced in the form of fields of ascending surges (fig. 3.6).
For problem solving of a stratigraphic control of reflexes, and also coordination of data ВСП, ГИС and a land seismics constructing of the composite schema is carried out. A key member of this schema is summary seismogram VSP with deduced on a vertical (or straightened) lines of correlation of back waves. Such transforming of records allows to meliorate conditions of a reflexion correlation and, the most important thing to erect exact locus of their index point.
The transforming essence consists in reduction of records of seismograms to conditions of vertical dip and passing of a dual path of run by it. For vertical reduction to routines of input of the spread corrections counted from the velocity law are used.
The maintenance and forming of the composite schema are esteemed in part 4.
Composition of routines of the count of the basic data processing not longitudinal VSP is demonstrated on fig. 3.7. A final and most relevant problem of all treating of materials VSP, in particular, is constructing of time sections VSP - the basic source of the information on a geological feature near-hole rooms.
Original routine of this count - specification of the high-speed law at the expense of use of primary arrivals of the forward surge filed with far Shot.
Routines of calculation of theoretical time-distance curves, calculation and input of spread corrections are similar to that at treating of ground-level unitary observations. Separation of a field of back waves is carried out the same as at treating of observations on a longitudinal profile.
Feature of definitive routine of constructing of a time section consists in forming from observed traces - a trass with the fixed abscisses of reflexion points (or a trass with the communal fixed dot).

P,P & R components

 

 

 

 

 

 

 

 

 

 

 

SPECIFICATION OF HIGH-SPEED CHARACTERISTICS OF ENVIRONMENT
CALCULATION OF THEORETICAL HODOGRAPHS
CALCULATION AND INPUT OF KINEMATIC AMENDMENTS
ALLOCATION OF THE FIELD OF THE REFLECTED WAVES
FORMATION OF THE TIME SECTION

Stage of treating in the present report we have engaged calculation of attenuation coefficients (occluding) αp a forward longitudinal wave. Definition αp is carried out on the basis of the analysis of variation of amplitudes of incidenting longitudinal waves in a band in width ΔТ=0.110  s, with, forward surge Р confined on the one hand to primary arrivals and the proximate to it one-two companions on the other hand. This routine is preceded by the account of a geometrical discrepancy.

a Fig. 3.7 Structure of procedures of data processing  

 

On a yield held treatings and data interpretations VSP are received following basic productive materials:
- Summary seismograms VAP with record of a wave field on X-, Y-, Z-components;
- The composite schema of a stratigraphic control of reflexes of longitudinal waves;
- Profiles of the resulted time-depth curves of straight lines incidenting longitudinal P- and cross SV-waves;
- Profiles of mean, sheet and interval velocities longitudinal and transverse waves and complex argument γ=Vs/Vp, functionally linked to a Poisson's ratio in the form of following expression [5, 7]:

γv==√(1-2σ)/2(1-σ)

- The table of functional link of times of run longitudinal and transverse waves with depth t0=f(H) (the tabular form of the resulted time-depth curves P- and SV-waves);
- Time and depth profiles VSP on longitudinal and exchange back waves on a line Hole-Shot2.
Except the enumerated materials, in the report amplitude curves and relative effective attenuation coefficients (occluding) of a forward incidenting longitudinal wave are introduced

The analysis of features of a wave seismic field