Hydrocarbon Sealing Potential of Faults
and Cap Rocks

Program Manager: Dr John Kaldi

The accurate evaluation of seals is a major part of the estimation of the efficiency of any petroleum system. In the past the general method of estimating the efficiency of the seal has been qualitative in nature and often arbitrary judgements have resulted in the wrongful estimate of risk associated with this part of the system. Recent developments in integrating geological, geochemical, geomechanical and petrophysical data has resulted in the ability to provide better risk evaluation. This program builds upon the multidisciplinary capabilities of the Centre and its APCRC partners to provide criteria to identify and quantify risks in top seals and faults. A significant development to the program in 2000 was the formation of an industry consortium comprising 9 companies contributing funds and data to the program: BHP, Chevron, OMV, Santos, Origin, Woodside, Esso-Mobil, Globex and JNOC. A very successful 2 day Technical Review (Tech-Fest) was held in the McLaren Vale region in November, where all researchers presented summaries of their work and had feedback from industry representatives.

Aims and Benefits of Program

  • Quantitative prediction of top and fault seal potential to improve estimation of prospect and play risk
  • Improved understanding of geological components contributing to seal potential of cap rocks
  • Improved understanding of criteria necessary to determine whether faults are seals or conduits in specific basins/petroleum systems
  • Improved understanding of the mechanics of fault reactivation, leading to improved estimation of seal vs. conduit behaviour
  • Improved prediction of fault breach risk from the relationship between fault and regional stress orientations

    Project 1: Evaluating the seal potential of regional cap rocks and intra formational barriers

    PhD Project: Regional Seal Evaluation: Vulcan/Browse Sub-basin, NW Shelf, Australia
    PhD Student: Tomasz Kivior (Commenced 1998)
    Supervisors: Dr. John Kaldi, Dr. Geoff O'Brien (AGSO)
    Funding: APCRC, AGSO

    MSc Project: Hydrocarbon Seal Evaluation: Nappamerri Group and Cuddapan
    Formation (Triassic), Cooper Basin, South Australia
    MSc Student: Rodica Dragomirescu (commenced 1999)
    Supervisors: Dr John Kaldi, Dr Nick Lemon, Elinor Alexander
    Funding: Primary Industries and Resources, South Australia (PIRSA)

    Project 2: Evaluating Seal Potential of Faults and Risk due to Fault Reactivation
    Research Personnel: Scott Mildren, Richard Hillis

    Richard Hillis gave a 3-day Petroleum Geomechanics course to JNOC at the invitation of Dr. Uko Suzuki, the JNOC representative on the seals program steering committee. Seals-related issues were a key component of the course which was set up at the Seals Techfest held in November 2000.

    Two manuscripts in the seals/faults seals area are being worked up by seals program researchers. These cover the fault seal risk cube and fault reactivation-related breach (FAST).

    Initial work on FAST by Scott Mildren, who joined the project as a research fellow in March, has involved specification of FAST analysis covering inputs and data formats. The next step is to work on integrating FAST into a single, stand-alone software package that can be supplied to consortium members for analysis of fault reactivation-related seal breach.

    Project 3: Geomechanical analysis
    Research Personnel: Richard Hillis, Dave Dewhurst (CSIRO)

    The aim of this part of the program is to elucidate the geomechanical properties of fault rocks that trap hydrocarbon columns. Cemented fault rocks, cataclasites and phyllosilicate fault rocks, and associated reservoir rocks, have all been tested in order to provide geomechanical data, including failure envelopes for FAST map fault seal prediction. Integrated microstructure and petrophysical studies of these fault rocks have also been undertaken.