P. CRISTEA, V. MANJ, C. NITICA
(REZUMAT)
Aplicatiile seismicii de refractie necesita prelucrarea performanta a datelor
de teren, îndeosebi procedee bazate pe tehnologie computerizata dedicata.
Ca urmare a acestei cerinte, a fost dezvoltat un program soft complex cu ajutorul
mediului de programare Borland Delphi orientat pe obiecte.
Bazat pe conceptul metodei undei transmise, software-ul, denumit REFRACTPROCESS,
opereaza cu date achizitionate atât în tehnica liniei seismice
de refractie, cât si în cea seismografica. Ultima tehnica, diversificata
pentru cele doua configuratii sursa-receptor, adica sisteme de observatie sonda-suprafata
si sonda-sonda, are capacitatea de a permite abordarea de sectiuni transversale
caracterizate prin viteze constante si, de asemenea, cazuri în care mediul
acoperitor este particularizat prin cresterea liniara a vitezei cu adâncimea.
Programul numeric ce ruleaza ofera doua feluri de sectiuni seismice: una cu
fragmente de tautocrone (curbe loc-timp), înfasuratoarea lor descriind
orizontul de refractie si o alta, cu variatia gradata a valorilor unghiului
de înclinare a partilor potential refractante, situate de-a lungul fiecarei
tautocrone. Deoarece acest ultim tip de informatie este un atribut nou ce poate
fi obtinut din datele de refractie initiale, relatiile analitice ce definesc
secventele programului soft specific sunt prezentate in extenso.
Deoarece metoda de refractie seismica este de obicei folosita în domeniul
explorarii minerale, tehnica de prelucrare realizata a fost experimentata pe
câteva linii seismice localizate pe depozitul de sare din zona Cacica
(judetul Suceava). Sectiunile efectuate au dovedit capacitati de prelucrare
pentru a obtine rezultate precise în conditii atât de suprafata
topografica neregulata cât si de morfologie ne-uniforma a limitei de
refractie.
Î
n sfârsit, este de notat ca atât acuratetea, cât si eficienta
fiecarei secvente a programului soft, completata de imaginile cromatice cuprinzatoare
ale sectiunilor seismice sunt proprietatile deosebite ale tehnicii de prelucrare
propuse.
Mots clés- Sismique réfraction, onde conique, onde transmise,
courbe tautochrone, angle dinclinaison de discontinuité de réfraction,
gisement de sel gemme de Cacica.
Abstract.-The actual seismic refraction applications require performant field
data processing, especially procedures built on computerized technology. Consensually
to this exigency, a complex soft-program has been developed by means of the
Borland Delphi visual objects programming medium.
Based on the transmitted wave method concept, the software, called REFRACTPROCESS,
operates with data acquired by both seismic refraction line and seismography
techniques. The last technique; diversified for its two shotpoint-receiver
configurations, i.e., well-to–surface and well-to-well observation systems,
has the ability to approach cross-sections characterized by constant velocities
and also cases in which the overlaying medium is particularized by linear increase
of velocity with depth.The numerical program running exhibits two kind of seismic
sections : one with fragments of tautochrones (loci-time curves), their envelop
describing the refracting horizon, and another with gradual variation of the
dip angle values of the potential refractor parts, situated along each tautochrone:
As the last kind of information is a new attribute obtainable from initial
refraction data, the analytic relations which define the specific soft- program
sequences are presented in extenso .
Due to the fact the seismic refraction method is usually applied in the mineral – exploration
field, the accomplished processing technique has been experimented on a few
seismic lines located on the salt deposit in the Cacica area (Suceava county).
The performed sections proved the proceeding capabilities to obtain accurate
results in conditions of both irregular topographic surface and un-uniform
morfology of the refracting boundary.
Finally, to be note that both accuracy and efficiency of each soft-program
sequence, completed by the comprehensive chromatic images of the seismic sections
are the preeminent properties of the proposed processing technique.
Key words.- Seismic refraction, critically refracted wave, transmitted wave, refracting boundary dip, Cacica salt deposit