3-D seismic and offset VSP data for delineation of a horizontal well trajectory: Bloque IV, Lake Maracaibo

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · AAPG Bulletin

OSTI ID:421041

Barrientos, C; Johnston, S ^[1]; Leon, K ^[2]; Stewart, L; Bryant, I D ^[3]

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1. Schlumberger Surenco, Caracas (Venezuela)
2. Maraven S.A., Caracas (Venezuela)
3. Schlumberger-Doll Research, Ridgefield, Connecticut (United States)

3-D seismic data were combined with well data to provide the broad structural framework necessary to define a horizontal infill well location in the Lower Lagunillas reservoir of Bloque IV; however, the low vertical resolution of the data precluded detailed interpretation of the thin (c. 30 ft) target horizon. Horizon slices through the 3-D volume indicated lineations that might represent faults or flexures that are below resolution of the data. An offset VSP was recorded in the pilot well with a source location positioned so as to illuminate the planned well path. The frequency content of the VSP (up to 50 Hz) was much higher the dominant frequency of the surface seismic (10 Hz). The VSP provided indications of good reservoir continuity and possible improvement in reservoir quality downdip. The dip of the formation in the plane of the well path, a critical parameter for steering the well, was confirmed as close to 3 degrees. The well subsequently confirmed these indications. it appears that offset VSPs offer the potential to significantly reduce drilling risks associated with horizontal wells in Lake Maracaibo, even when 3-D surface seismic is already available.

• OSTI ID: 421041
• Report Number(s): CONF-9609255--
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 8 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
DIRECTIONAL DRILLING
OIL FIELDS
PETROLEUM DEPOSITS
RESERVOIR ENGINEERING
SEISMIC SURVEYS
VENEZUELA