Application of logging-while-drilling spectroscopy to evaluate volume of clay, grain density, and porosity in a low porosity, high temperature environment—offshore Western Australia
Paolo Bartelucci A , Mauro Firinu A , Anthony Jones B and Ping Yan BA Eni Australia.
B Schlumberger.
The APPEA Journal 54(2) 533-533 https://doi.org/10.1071/AJ13106
Published: 2014
Abstract
Formation evaluation in low porosity, low salinity, and high temperature reservoirs poses many challenges. The environment is hostile to many logging tools due to their temperature limits and there is greater uncertainty related to petrophysical parameters compared with conventional formations. Additionally, in low porosity and low salinity reservoirs, resistivity contrast between hydrocarbon and water filled rocks is often missing. This extended abstract presents a case study from offshore WA where a petrophysical model has been created with logging while drilling measurements including spectroscopy data to improve estimation of mineralogy, clay volume, and porosity, thereby reducing saturation evaluation uncertainty. Spectroscopy measurements can be analysed to derive dry weight elemental concentrations of various elements such as silicon, calcium, iron, and sulfur. These concentrations have been subsequently used as input to compute a multi-mineral petrophysical model using a least squares inversion technique. We demonstrate that spectroscopy can be used independently to obtain an accurate volume of clay instead of gamma ray, spontaneous potential, or porosity logs. Moreover, matrix properties such as grain density, which enhance the accuracy of porosity estimation derived from bulk density, are also derived from spectroscopy dataset. Good agreement with core validates the petrophysical model. Also demonstrated is how the petrophysical model reduces the uncertainty in clay volume and porosity, from which more accurate water saturation can be derived in these tight reservoirs. Calibrating the spectroscopy information to core data allows the mineralogical and geological model to be extended to the intervals where core data are not available.
Paolo joined Eni in Milan HQ in 2008 as a Junior Petrophysicist, where he had intensive training in both the reservoir and exploration disciplines. There he was also involved in reservoir characterisation research and development projects, supporting explorative and development projects. In 2010 Paolo moved to Algeria following rig and rigless activities on field. Then in 2011 he moved to the Eni Operational District in Ravenna as part of the petrophysical team, where he gained further experience in clastic and carbonatic reservoirs. Finally in February 2013 he moved to Eni Australia in Perth as a Senior Petrophysicist for the Exploration and Operation Departments. |
With more than 25 years of experience in oil and gas industry, Mauro served operation geology and petrophysical activities for Eni in several projects, numbers of countries (Europe, North and West Africa, Asia, US) and in different positions (Well Site Geologist, Petrophysicist, Operation Geology Coordinator, and Subsurface Geology Manager). Author of several technical papers and lectures in Formation Evaluation, he was recently awarded for a distinguished contribution to Petroleum Engineering in Formation Evaluation by SPE South Central and East European Region in June 2013. He’s currently Head of Operation Geology and Petrophysical activities for Eni Australia in Perth. |
Anthony Jones is a Schlumberger PetroTechnical Services (PTS) Petrophysicist. He holds BE/BSc (2002) and PhD (2008) degrees from the Australian National University (ANU) in Canberra. He joined Schlumberger in 2009 and has two years’ experience as a field engineer in the Middle East, Russia, and Australasia. He is currently working on interpretation and support of logging while drilling and wireline acquisition. |
Ping Yan is a Schlumberger PetroTechnical Services (PTS) Petrophysicist based in Perth, Australia. She received Bachelor (2004) and Master (2007) degrees from China University of Petroleum (CUP) in Shandong Province. She joined Schlumberger in 2007 and worked in Beijing for 5 years and 8 months as a Petrophysicist. She transferred to Perth in May 2013. She is currently working on interpretation and support of logging while drilling and wireline acquisition. |
References
Cadman, S.J., and Temple, P.R., 2003—Bonaparte Basin, NT, WA, AC & JPDA. Australian Petroleum Accumulations Report 5, 2nd Edition. Canberra: Geoscience Australia.Herron, S.L., and Herron, M.M., 2000—Application of Nuclear Spectroscopy Logs to the Derivation of Formation Matrix Density. Society of Petrophysicists and Well-Log Analysts.
Neville, T.J., Weller, G., Faivre, O., and Sun, H., 2007—A New-Generation LWD Tool With Colocated Sensors Opens New Opportunities for Formation Evaluation. Society of Petroleum Engineers, https://doi.org/10.2118/97224-PA.
