The geology of the Lauterbach Gasfield: Geologic modeling in a complex depozone

Martin Andreas Geissler

Research output: ThesisMaster's Thesis

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Abstract

The Lauterbach Gas Field is located in a wedge top deposition environment resulting in a complex architecture. Therefore, every well drilled delivered new insights and altered the perception of reservoir setting. Thus, the aim of the present master thesis is to build a geologic 3D model that reflects the complexity of the reservoir and fulfils the needs of a dynamic reservoir simulation. A dataset provided by Rohöl-Aufsuchungs AG consisting of 3D seismic data and well data forms the base for this study. The Lauterbach Basin is a piggyback basin that formed on top of the Molasse Imbrications and is located at the border of Salzburg and Upper Austria. The basin has an extension of approximately 5.5 x 3.5 km and is truncated in the south by the Alpine thrust system. Above the base, formed by a regional erosional event, five productive reservoir layers were deposited. Turbiditic sediments were shed into the basin from SSE directions. In some layers a second input direction from E is identifiable. The key elements in basin history are the synsedimentary stress from the underlying moving Molasse Imbrications that led to soft deformation of the sediments and a large number of erosive events that are represented in the sedimentary succession. Well log correlation and seismic interpretation in this setting are challenging, because bed thickness is often not much greater than seismic resolution. As a consequence, top and base of a reservoir layer cannot be mapped separately in seismic. According to synthetic seismograms, the reflectors were chosen to represent the top of the reservoir sections. The base of each reservoir successions was constructed using thickness maps that are based on amplitude variations along the seismic reflectors. Furthermore, pressure data from production tests formed a valuable assist in the identification of reservoir connectivity. To characterize the geology of the Lauterbach Basin, a facies model of the reservoir was built using an object based modeling technique. The definition and distribution of different facies groups within the reservoir is essential for the calculation of hydrocarbon volume in place, which was also carried out. The results showed an excellent fit with independent estimates derived from production pressure data.
Translated title of the contributionDie Geologie des Lauterbach Gasfeldes
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Sachsenhofer, Reinhard, Supervisor (internal)
Award date17 Dec 2010
Publication statusPublished - 2010

Bibliographical note

embargoed until 23-09-2015

Keywords

  • Molasse Basin (Austria)
  • Piggyback Basin
  • Turbidites
  • Geologic modeling

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