ALBERT

Description: A depth migration is very sensitive to tl1e velocity model especially in the case of steeply dipping reflectors like the so-called SE reflectors at the KTB site. Velocity models derived from first breaks in vertical seismic profiling (YSP) experiments were used and compared with velocity data at the top of the crystalline refractor derived by short range measurements. Because of high picking errors, the possibility to compare seismic events with information of the upper part of the KTB HB hole allows only a very limited calibration of the velocity model. Based on the cutting profile, we assume that the reflectors SE-2 and SE--3 represent faults at 3600-3660 m depth and 5440-5560 m depth ( or a lithological contrast at 5540-5610 m depth). We suppose that the velocity of an average model starts at about 5.2 km/s at the surface, reaches a value of 6.0 km/s in about 2.5 km depth and remains approximately constant below. In that case, the reflector SE-1 will be hit at a depth of 7 .0 km. Because of the steep dip of reflector SE-1 which increases the size of the error range (from inaccurate velocity models and picking errors). the tolerance of about ±0.4 km is very high.

Description: The 3-D expanding spread experiment, performed within ISO 89 at the KTB site, has been evaluated under two aspects. The first aspect was the estimation of velocity-depth functions. Due to the limited reflection strength, estimating NMO velocities as a function of twoway traveltime was possible in east-west direction only. Thus the calculation of interval velocities, requiring the correction of 3D effects, was not possible. The second aspect was the directional dependency of the P-wave velocity at the top of the crystalline by evaluating the direct waves. After eliminating the effects of the lithology, a least-mean-squares anisotropy-velocity ellipse was fitted to the data with WSW as the direction of the maximum velocity and a velocity contrast of about 6%.

Description: A preliminary interpretation of the major 3-D reflectors is given by correlation with the surface geology and the drilled sections of the KTB Vorbohrung and the Hauptbohrung. Possible explanations for the reflections are discussed: lithological boundaries, cataclastic fault zones (partly filled with fluids) and other structural properties (e.g. foliation). Flat reflectors near the surface (MFl - 4) can be correlated with Permocarboniferous and Mesozoic sediments of the South German Platform. Special attention is drawn to a group of steeply NE-dipping reflectors (SEl, SE2, SE3) which are, obviously, produced by en-echelon fault structures of the Franconian Lineament. In the boreholes, SE2 can be identified as a bundle of faults near 3600 m. The calculated depth of the most prominent reflector SEl in the Hauptbohrung is between 6600 and 7100 m. It represents, probably, a deepreaching reverse fault zone which produces an offset of the reflections of the midcrustal "Erbendorf body" (B1 - B2/G4 - Gl).

Description: The determination of 3D-static corrections usually is possible only with the exact knowledge of thickness and velocity of the superficial layers. In order to determine these parameters extensive additional measurements are necessary, e.g. refraction seismics. These measurements can be reduced considerably if there is already a borehole in the survey area; the shots generated for the seismic survey can be recorded with a borehole geophone chain. The direct traveltimes determined from these records are lying on a 2nd-order plane (ideally a hyperboloid). If these traveltimes are influenced by e.g. differences in the elevations of the source location or velocity inhomogeneities, the first arrival traveltimes scatter around such a hyperboloid. The static corrections can be determined from the difference between the measured traveltime and the ideal hyperboloid. Further measurements are not required, because a precise knowledge of the parameters of the weathered layer is not necessary. In the following a method is presented (developed by Albrecht (1991) and Teichert (1991)) to determine the theoretical hyperboloid. Another method, described at the end of this report, is the determination of average velocities from picked and corrected first arrival traveltimes.

Description: A kinematic evaluation of first breaks of the direct P-wave in several VSPs, carried out at the KTB pilot hole in 1988 and 1989, is presented. After picking and correction to vertical traveltime, average and interval velocities were computed. The average velocity increases with depth caused by the successive closing of microcracks under increasing confining pressure. Tl1is average velocity-depth curve is the most accurate velocity information at the KTB site and can be used in migration and time-depth conversion problems in 2D- and 3D reflection surveys.

Description: The recordings of the wide-angle shots by 3-component geophones in the KTB pilot hole exhibit the effect of shear-wave splitting, that is the most diagnostic evidence of seismic anisotropy (Crampin, 1989). The possible reasons for seismic anisotropy will be discussed and the lateral extension of the anisotropic region will be estimated.

Description: Based on the DEKORP ISO 89 borehole experiments, the question of the existence of "seismic anisotropy at the KTB deep drilling site" has to be answered unambiguously with "yes". The anisotropy could be quantified in situ for a gneiss packet where it is apparently influenced by both rock foliation and cracks. The values obtained in the direct vicinity of the KTB pilot hole, however, cannot be extrapo l ated into its surroundings without modification: While the general trend of anisotropy with high velocity values towards SE-ESE is conserved, the amount of anisotropy shows smaller average values. This seems to reflect the inhomogeneous distribution of metamorphic rocks and granite in the target area. The direction of high seismic velocities (ESE) coincides approximately with the postulated direction of maximum horizontal tectonic stress in the Oberpfalz region.

Description: The detection of permeable fractures is one of the research objectives of the KTB-project. Among seismic methods the tube wave survey is suggested for this purpose. Open permeable fractures intersecting the borehole may generate secondary tube waves which show up as V-shaped traveltime patterns (Chevron pattern) in sonograms. We investigated tube waves transmitted and recorded by the VAL-(Variable Acoustic Logging)-tool technique. The depths of tube wave generation were determined. 85 percent of them correlate with planar structures seen in acoustic borehole televiewer (BHTV) logs. BHTV data reveal many structures. One third of these coincide with tube wave events in the VAL data. To verify the hypothesis that the occurence of a structure in both, traveltime and amplitude displays of BHTV data indicates an open fracture, we compared this dataset with stronger tube wave events assuming that the latter can be correlated to open fractures. We found no evidence for the correctness of the hypothesis. We compared tube wave events with caliper logs, temperature and mud conductivity anomalies during hydraulic tests, temperature anomalies during heat exchange test, core sample observations and gas-geochemical anomalies The comparison between these various borehole data is not as satisfactory as to ensure the reliability of tube wave analysis to determine open fractures. Earlier investigations suggest that amplitudes of tube wave events are related to hydraulic permeabilities. Deficiencies of the present tube wave dataset (VAL) and missing fluid logging for calibration purposes prevents us from quantitative analysis.

Description: Dürbaum, H.-J.: Introduction. p. 1-2. Stiller, M.: Preliminary generation of a stacked data volume of the entire ISO'89-3D data set using an envelope technique. p. 3-29. Hluchy, P., Körbe, M., Thomas, R.: Preliminary Interpretation of the 3D-Seismic Survey at the KTB Location. p. 31-52. Stiller, M., Tormann, M.: Application of a simplified horizon migration process to the data of the 3D-seismics ISO'89. p. 53-65. Wiederhold, H.: Interpretation of envelope-stacked 3D seismic data and its migration - another approach. p. 67-113; Hannover. Körbe, M., Reichert, C.: On the character of "Steep Event SE-1" reflected energy, reflected refraction, diffraction or any artifact?. p. 115-131. Janik, M., Harjes, H. P.: Structural Interpretation of the MSP-Experiment. p. 133-148. DEKORP Research Group: Depth determination of prominent seismic structures beneath the KTB main drillhole KTB-HB. p. 149-160. Simon, M.: Structural images from 3D-isochron migration of wide-angle data in the surroundings of KTB. p. 161-168. Söllner, W., Lüschen, E., Li, X.-P., Hubral, P., Gut, T. W., Widmaier, M.: VSP - A Link between Reflection Seismic Profiling and Lithology. p. 169-199. Rühl, T., Hanitzsch, C.: Average and interval velocities derived from first breaks of vertical seismic profiles at the KTB pilot hole. p. 201-219. Bönnemann, C., Buttkus, B: Results of the 3-D expanding spread experiment. p. 221-232. Martini, N., Stiller, M.: Results of the ISO'89 experiment "Durchschallung": Recording of the vibrator sweeps of the 3D-seismics in the KTB borehole. p. 233-246. Lüschen, E., Werner, U.: Fluid/Gas indications in 8 km depth beneath the KTB and rock anisotropy from shear-wave reflection surveys. p. 247-274. Rabbel, W.: Seismic anisotropy at the KTB Deep Drilling Site. p. 275-289. Gut, T. W., Söllner, W., Lüschen, E., Edelmann, H. A. K.: More reliable shear-wave data from VSP by using CIPHER-technique. p. 291-295. Bopp, M: Shear-wave splitting observed by wide-angle measurement. p. 297-308. Hanitzsch, C., Rühl, T., Heinemann, B. B.: Detection of permeable fracture zones by tube waves in the KTB pilot hole. p. 309-332. Hanitzsch, C., Hubral, P., Rühl, T., Söllner, W.: Migration of steeply dipping reflectors at the KTB site: Depth errors caused by inaccurate velocity models. p. 333-341. Stettner, G.: Zur Korrelation des tektonischen Baues mit den seismischen Strukturen im Raum KTB-Oberpfalz - Münchberger Gneismasse. p. 343-349. Hirschmann, G.: On the Geological Interpretation of the 3-D Seismic Data with Special Regard to the Information from the KTB Boreholes. p. 351-373.

Description: Dietrich, H.-G., Lauterjung, J., Wöhrl, Th.: Introduction. p. A1-A26. Lich, S., Duyster, J., Godizart, G., Keyssner, S., de Wall, H.: German Continental Deep Drilling Program (KTB) - Geological Survey of the Hauptbohrung 0 - 6000 m. p. B1-B42. de Wall, H., Lich, S.: Drilling Artifacts in Cuttings Samples. p. B43-B46. Hirschmann, G.: The Geological Section of the KTB Hauptbohrung - Correlation with the KTB Vorbohrung and preliminary structural interpretation. p. B47-B52. WGs Geology, Geochemistry, Geophysics: Cutting Profile. p. B53-B83. Figgemeier, Chr., Machon, L., Kamm, H., Hansmann, J., Gleiß, N., Umsonst, T., Zimmer, M.: KTB Hauptbohrung, Geoscientific Investigations in the KTB-Field- Laboratory, Depth interval 0 - 6000 m: Geochemistry/Mineralogy. p. C1-C38. Erzinger, J., Hansmann, J., Kamm, H., Heinschild, H.-J.: On-line Determination of 222-Radon in Drilling Fluids of the KTB Hauptbohrung. p. C39-C45. Pribnow, D., Bücker, Ch., Rauen, A., Spangenberg, E., Wienand, J., Soffel, H.C.: KTB Hauptbohrung, Geoscientific Investigations in the KTB-Field- Laboratory, Depth interval 0 - 6000 m: Geophysics. p. D1-42. Röckel, Th., Natau, O.: KTB Main Hole, Geoscientific Investigations in the KTB-Field- Laboratory, Depth interval 0 - 6000 m: Rock Mechanics. p. E1-E7. Röckel, Th., Natau, O., Dietrich, H.-G.: Core Reorientation by Comparison of Core Instabilities and Borehole Instabilities. p. F1-F17. Rischmüller, H., Chur, C., Engeser, B., Hoffers, B., Sperber, A., Tran Viet, T., Wohlgemuth, L.: Advanced Drilling Technology for the Continental Deep Drilling Program (KTB): Part of International Lithosphere Research. p. G1-G17.

Description: Hirschmann, G.: Vorläufige strukturelle Interpretation von KTB-Vor- und Hauptbohrung. p. 3-6. Schalkwijk, G., Stöckhert, B.: Metabasites in the pilot borehole of the KTB, structures and fabrics. p. 7-13. Pieper, U., Stöckhert, B.: Quantitative analysis of reaction fabrics in the KTB-pilot-borehole. p. 15-22. Heinisch, H.,Kohl, J.,Sprenger, W.,Zadow, A.: Kinematische Analyse von Porphyroklasten-Systemen in Gneisen der KTB-VB auf der Basis kontinuierlicher Kernaufnahme. p. 23-41. Heinicke, F.,de Wall, H.: Gefügeuntersuchungen an Paragneisen aus der KTB-Vorbohrung. p. 43-66. Vollbrecht, A.,Weber, K.: Mikrorisse und Quarz-Deformationslamellen in Paragneisen der KTB-Vorbohrung: Indikatoren für Paläospannungsrichtungen. p. 67-83. de Wall, H.,Huenges, E.,Weber, K.: Untersuchungen zur Richtungsabhängigkeit der Wärmeleitfähigkeit an Paragneisen der KTB-Vorbohrung. p. 85-99. Weber, K.: Die tektonische Position der KTB-Lokation. p. 103-132. Stein, E.,Kleemann, U.: Evidence for Late Variscan emplacement of the ZEV. p. 133-146. Bernbach, W.,Stein, E.: Die Tektonik im zentralen Teil der Zone Erbendorf-Vohenstrauss (ZEV). p. 147-159. Rohrmüller, J.,Höll, R.,Stettner, G.: Deformationsmerkmale im Umfeld der Kontinentalen Tiefbohrung (KTB) Windischeschenbach/Opf. p. 161-169. Stettner, G. (1992): Zu den tektonischen Beziehungen zwischen der Neustädter Scholle (ZEV), der Erbendorfer Grünschiefereinheit und dem Moldanubikum. p. 171-179. Röhr, C.,Zulauf, G.: Zur tektonometamorphen Entwicklung der Erbendorfer Grünschieferzone - abgeleitet aus petrologischen, geothermobarometrischen und strukturgeologischen Untersuchungen. p. 181-212. Franke, W.,Prössl, K. F.,Schwarz, J.: Devonische Grauwacken im Erbendorfer Paläozoikum - Alter, tektonische Stellung und geotektonische Bedeutung. p. 213-223. Franke, W.,Behrmann, J.,Moehrmann, H.: Zur Deformationsgeschichte des Kristallins im Münchberger Deckenstapel p. 225-240. Lapp, M.,Weber, K.: Postkinematische Alteration von Metagrauwacken und Phylliten der Bohrung Neualbenreuth p. 241-250. Stein, E.: Die Alterstellung der Arzberger Serie, abgeleitet aus der tektonischen Entwicklung des S' Saxothuringikums p. 251-260. Skrotzki, W.,Weber, K.,Müller, W. F.: Gefügekundliche Untersuchungen im KTB mittels TEM. p. 261-276. Maier, M.,Stöckhert, B.: Conditions of crystallization and deformation of the Falkenberg Granite/Eastern Bavaria, Germany. p. 277-286. Schröder, B.: Post-Hercynican fault block activities in the basement area near KTB - drilling site. p. 287-294. Franzke,H.-J.: Bruchentwicklung und hydrothermale Gangmineralisation an der Flossbergstörung bei Ilmenau/Thüringer Wald. p. 295-315. Teufel,S.,Ahrendt,H.,Hansen,B.T.: U-Pb-Isotopensystematik von Monaziten aus metamorphen Gesteinen der Oberpfalz. p. 319-331. Grauert, B.,Blümel, P.,Lork, A.: Hinweise auf prädevone und karbone Metamorphosen in Gneisen der KTB-Vorbohrung: Ergebnisse aus Rb-Sr-Kleinbereichsanalysen. p. 333-347. Wemmer, K.,Ahrendt, H.: Geochronologische Erfassung von retrograden Prozessen in Gesteinen der KTB-Vorbohrung mit Hilfe der K/Ar-Methode. p. 349-372. Welzel, B.,Ahrendt, H.,Behr, H.-J.,Schröder, B.,Weber, K.: Die Bedeutung von K/Ar-Datierungen an detritischen Muskoviten fr die Rekonstruktion tektonometamorpher Einheiten im erweiterten KTB-Lokationsgebiet. p. 373-397. Welzel, B.,Ahrendt, H.,Behr, H.-J.,Schröder, B.,Weber, K.: Alter und Intensität der postsedimentären Überprägung im erweiterten KTB-Lokationsgebiet (Ostteil der Süddeutschen Scholle). p. 399-415.

Description: Behr, H.-J., Gerler, J., Große, S., Heinrichs, T., Löffler, T., Reutel, Chr., Schmidt-Mumm, A., Welzel, B.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation. p. 3-85. Gerler, J., Schmidt-Mumm, A., Behr, H.-J.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 1.4.2 Thermische Schallemissionsanalyse. p. 13-17. Behr, H.-J., West, M.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 1.4.3 Röntgen-Tomographie an Bohrkernen. p. 17. Behr, H.-J., Große, S., Heinrichs, T.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 2.0 Störungstektonik und Schwerefeld am Westrand der Böhmischen Masse. p. 17-19. Löffler, T.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 6.1 Sedimentologisch-fazielle Profilaufnahme der Thermalwasser-Bohrung Weiden. p. 47-52. Welzel, B.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 6.2 K/Ar- Datierungen an detritischen Muskoviten aus dem Permokarbon der Bohrung Weiden. p.52-55. Behr, H.-J., Reutel, Chr.: Lineare Krustenstrukturen im Umfeld der KTB-Lokation: 8.0 Krustenstruktur und Krustenfluide. p. 58-61. Hirschmann, G. : Das Bruchstörungsmuster im KTB-Umfeld. p. 85-124. Lich, S., Hirschmann, G.: Petrographische Bearbeitung der Weitwinkel-Schußbohrungen ISO 89. p. 127-164. Dahlheim, H.-A., Gebrande, H., Schmedes, E., Soffel, H.C.: The KTB Seismological Network. p. 167-204. Günzel, F., Soffel, H. C.: Feldmagnetische Bodenmessungen im Bereich des Amphibolitkörpers der KTB-Bohrung und ihre Interpretation. p. 207-228. Soffel, H. C., Harzer, F.: Palaeomagnetic Investigations on Permo-Carboniferous Rocks in the Area of the KTB Drill Site. p. 231-245. Worm, H.-U.: Die Anisotropie der magnetischen Suszeptibilität in der KTB-Oberpfalz VB. p. 249-261.

Description: For several reasons the IS0'89 3D-seismic data are at hand not as conventional, phase-consistent stack so far but as 'envelope stack' only. Therefore, the common wave-field migration procedures cannot be applied to attain information on the spatially correct position of the particular reflector elements. To cope with this problem a simplified 3D-horizon migration program was developed at the DEKORP Processing Center Clausthal. It allows to migrate not the sejsmic traces of the IS0'89-3D survey themselves but the traveltime values for specific horizons derived by interactive picking with a 3D-seismic interpretation system on the basis of an envelope stack. The motivation, the basic assumptions and the principles of this procedure are outlined as well as the mathematical background and the particular processing steps. The migration results of some selected key horizons in the area of the KTB are depicted by isochrone maps and 3D-views. By this, a preliminary geological interpretation based upon the true position and shape of several detected seismic surfaces is enabled although the final processing, i. e. a phase-consistent stack of the entire JO-dataset (and its subsequent wave-field migration), has not been finished yet.

Description: A preliminar)' interpretation ha, been done on an envelope tack of the three-dimen ional eismic nrW)' of the ISO 89 experiment. This kind of~ tack is interpretable as well a a normal stack with ome re tri tion . but all major elements are detectable. The major tructural elemPnt , which haw been the targPt of the interpretation in thi special case. can be diYided into five groups. The three most important groups are a bundle of steeply northeast dipping reflections with outcrops in the area of the outcrop of the Franconian Line. a zone of high refl.ectiYity with five reflections named Erbendorf body and two curved interfaces at the time range 3.5 to 4.5 s TWT. The results of this interpretation are in good correspondence to the former interpretations done on the two-dimensional seismic lines in the survey area.

Description: The heart of the Integrated Seisrnics Oberpfalz 1989 experiment (ISO89) is a 3D seismic survey with a subsurface covered area of 19.1 km* 17.85 km and the KTB borehole at its centre. The brute processing by the DEKORP Processing Center (DPC) at Clausthal resulted in an envelope-stacked data set that is used for a preliminary interpretation. Several strong reflections are addressed and mapped in 3D. The results are presented in form of time contour maps. For the depth conversion several velocity models are discussed and compared. The depth _ conversion itself is realized by a map migration of the interpreted horizons (SATTLEGGER 1986). The true 3D geometry for several horizons is presented as well as the depth they will be encountered in the KTB borehole.

Description: A reflection survey using shear-wave sources and 3-component receivers bas been performed on two orthogonal lines across the KTB-deep dril1ing site in the Oberpfa]z area (Bohemian crysta11ine Massif). A combination of surfaceconsistent statics and automatic residual statics proved to be of crucial importance to obtain good coherency and a good signal/noise ratio for deep crustal shear-wave reflections after CMP-stacking. Direct comparisons with previously processed standard P-wave CMP stack sections exhibit deep structures ('Erbendorf-body', 10-12 km depth) which reflect equally strong in P- and S-waves indicating normal lithological variations. In contrast to this, in 8 km depth a bright reflection is seen only on the P-wave section. It is absent on the S-wave section. This behaviour can be explained by two alternative geological models. The first one is an accumulation of fluid or gas under sti11 unknown reservoir condHions. The aJtemative, purely compositional model is a crystalline body with an anomalously low Vp!Ys-ratio. A rock mass with a high amount of quartz could also produce impedance contrasts for P-waves but not for S-waves. Pronounced S-wave splitting, observed for the 'Erbendorf-reflections, indicates that the symmetry system of the rock anisotropy is rotated by 90 degrees below 3 km against the one which was detected above 3 km by S-wave vertical seismic profiles.