The Use of Real-Time and Time-Lapse Logging-While-Drilling Images for Geosteering and Formation Evaluation in the Breitbrunn Field, Bavaria, Germany (2001)

The Use of Real-Time and Time-Lapse Logging-While-Drilling Images for Geosteering and Formation Evaluation in the Breitbrunn Field, Bavaria, Germany Hendrik Rohler; Hendrik Rohler RWE-DEA AG Search for other works by this author on: This Site Google Scholar Ted Bornemann; Ted Bornemann Schlumberger Search for other works by this author on: This Site Google Scholar Alexis Darquin; Alexis Darquin Schlumberger Search for other works by this author on: This Site Google Scholar John Rasmus John Rasmus Schlumberger Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 2001. Paper Number: SPE-71733-MS https://doi.org/10.2118/71733-MS Published: September 30 2001 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Rohler, Hendrik, Bornemann, Ted, Darquin, Alexis, and John Rasmus. "The Use of Real-Time and Time-Lapse Logging-While-Drilling Images for Geosteering and Formation Evaluation in the Breitbrunn Field, Bavaria, Germany." Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 2001. doi: https://doi.org/10.2118/71733-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractSix horizontal wells were drilled into the Tertiary Chatt Sand reservoir of the Breitbrunn gas field in Bavaria, Germany. The purpose of this campaign was to develop part of the depleted reservoir into a gas storage sand. A detailed geological and petrophysical study was prepared prior to drilling and resulted in the identification of high quality reservoir layers that were targeted by the horizontal wells. Despite the simple anticline structure of the field, geometric drilling was ruled out due to remaining geological and directional uncertainties. The geosteering approach adopted relies on real-time GeoVision Resistivity (GVR*) resistivity images, which were used for the first time ever during this drilling campaign. The image data are compressed downhole and transmitted to the acquisition computer on the rig where they are decompressed and analyzed. The images allow the precise placement of the borehole relative to the geology, which "keeps the bit in the sand". Layer heterogeneity like tight streaks, concretions or patchy porosity can be identified as such, and are not interpreted as a different layer entered by the hole, which would lead to a wrong geosteering decision. Logging-While-Drilling (LWD) azimuthal data are acquired during drilling and also during wash-down passes which follow a bit change. A comparison of these time-lapse data sets can provide invasion profiles through time and around the borehole.IntroductionThe Breitbrunn/Eggstatt gas field was discovered in 1975 in southern Bavaria, Germany (Fig.1). The NE-SW striking anticlinal structure covers about 30 square kilometers and consists, from top to bottom, of sands A through H with sands A through D being the original gas producers. The lower sands are wet. The individual reservoir layers range in thickness from about 5 to 15 meters and are separated by impermeable calcareous shales. The immature sands were deposited immediately north of the rising Alpine orogen during the Tertiary. Mineralogically they consist of carbonate sand, principally dolomite, quartz and micas. The sands were deposited in a fluvial/deltaic setting.Initial production was by vertical wells drilled on the top of the structure. After depletion of the reservoir, layers A and B were converted into a gas storage reservoir with layer B being the storage sand while layer A functions as monitoring unit for gas leak detection. The demand of natural gas during winter months in the region led to the drilling campaign discussed here with the aim of increasing the storage capacity of the reservoir. The remaining original gas sands C and D were targeted for storage development as it was known that they possess sufficient porosity and permeability although with greater geological and petrophysical heterogeneity than the upper two sands. Reservoir quality in this field deteriorates from the top sand downward.The drilling phase of sands C and D was preceded by geological, petrophysical and geomechanical studies.The goal of the geological study was to achieve a structural accuracy of 0.1%, which translates into a depth inaccuracy of maximal 1.5 meters. This was achieved by re-surveying well locations and using directional surveys from casing runs for adjusting all log-derived marker picks to a common baseline. The vertical pilot well and the subsequent horizontal development wells confirmed that this depth accuracy was achieved. Keywords: well logging, saturation, breitbrunn field, logging-while-drilling image, reservoir characterization, strength, upstream oil & gas, rock strength, bavaria, time-lapse logging-while-drilling image Subjects: Reservoir Characterization, Formation Evaluation & Management, Open hole/cased hole log analysis This content is only available via PDF. 2001. 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