DigiFract: A software and data model implementation for flexible acquisition and processing of fracture data from outcrops

This paper presents the development and use of our new DigiFract software designed for acquiring fracture data from outcrops more efficiently and more completely than done with other methods. Fracture surveys often aim at measuring spatial information (such as spacing) directly in the field. Instead, DigiFract focuses on collecting geometries and attributes and derives spatial information through subsequent analyses. Our primary development goal was to support field acquisition in a systematic digital format and optimized for a varied range of (spatial) analyses. DigiFract is developed using the programming interface of the Quantum Geographic Information System (GIS) with versatile functionality for spatial raster and vector data handling. Among other features, this includes spatial referencing of outcrop photos, and tools for digitizing geometries and assigning attribute information through a graphical user interface. While a GIS typically operates in map-view, DigiFract collects features on a surface of arbitrary orientation in 3D space. This surface is overlain with an outcrop photo and serves as reference frame for digitizing geologic features. Data is managed through a data model and stored in shapefiles or in a spatial database system. Fracture attributes, such as spacing or length, is intrinsic information of the digitized geometry and becomes explicit through follow-up data processing. Orientation statistics, scan-line or scan-window analyses can be performed from the graphical user interface or can be obtained through flexible Python scripts that directly access the fractdatamodel and analysisLib core modules of DigiFract. This workflow has been applied in various studies and enabled a faster collection of larger and more accurate fracture datasets. The studies delivered a better characterization of fractured reservoirs analogues in terms of fracture orientation and intensity distributions. Furthermore, the data organisation and analyses provided more independent constraints on the bed-confined or through-going nature of fractures relative to the stratigraphic layering.

[1]  Samarpan Dey,et al.  GRDM - A digital field-mapping tool for management and analysis of field geological data , 2008, Comput. Geosci..

[2]  Diana M. Allen,et al.  Regional evaluation of hydraulic properties in variably fractured rock using a hydrostructural domain approach , 2008 .

[3]  N. Fisher,et al.  Statistical Analysis of Circular Data , 1993 .

[4]  Alex K. Manda,et al.  Comparison of three fracture sampling methods for layered rocks , 2010 .

[5]  S. D. Priest,et al.  Determination of Discontinuity Size Distributions from Scanline Data , 2004 .

[6]  Robert W. Wilson,et al.  Digital geological mapping with tablet PC and PDA: A comparison , 2006, Comput. Geosci..

[7]  Graham J. Borradaile,et al.  Statistics of Earth Science Data , 2003 .

[8]  Boyan Brodaric,et al.  The design of GSC FieldLog: ontology-based software for computer aided geological field mapping , 2004, Comput. Geosci..

[9]  W. Dershowitz,et al.  Interpretation of fracture spacing and intensity , 1992 .

[10]  Konrad Hinsen,et al.  Numerical Python , 1996 .

[11]  Jean-Luc Mari,et al.  Feature Line Extraction on Meshes through Vertex Marking and 2D Topological Operators , 2011, Int. J. Image Graph..

[12]  E M Schetselaar,et al.  Computerized field-data capture and GIS analysis for generation of cross sections in 3-D perspective views , 1995 .

[13]  Doug Stead,et al.  Regional deterministic characterization of fracture networks and its application to GIS-based rock fall risk assessment , 2007 .

[14]  L. Király.  Statistical analysis of fractures (Orientation and density) , 1969 .

[15]  Emmanuel Gringarten,et al.  3-D geometric description of fractured reservoirs , 1996 .

[16]  Richard A. Schultz,et al.  Terminology for structural discontinuities , 2008 .

[17]  R. Nelson,et al.  Fractured Reservoirs: Turning Knowledge into Practice , 1987 .

[18]  G. Baecher.  Statistical analysis of rock mass fracturing , 1983 .

[19]  Terry L. Pavlis,et al.  Computer-based data acquisition and visualization systems in field geology: Results from 12 years of experimentation and future potential , 2010 .

[20]  Giovanni Bertotti,et al.  Distributed fracturing affecting isolated carbonate platforms, the Latemar Platform Natural Laboratory (Dolomites, North Italy) , 2013 .

[21]  David D. Pollard,et al.  Digital mapping of three-dimensional structures of the Chimney Rock fault system, central Utah , 2001 .

[22]  N. Odling,et al.  Scaling of fracture systems in geological media , 2001 .

[23]  Diana M. Allen,et al.  Regional fracture network permeability using outcrop scale measurements , 2009 .

[24]  S. Mitra,et al.  Structural controls of fracture orientations, intensity, and connectivity, Teton anticline, Sawtooth Range, Montana , 2009 .

[25]  N. P. Christensen,et al.  Variations in fracture system geometry and their implications for fluid flow in fractures hydrocarbon reservoirs , 1999, Petroleum Geoscience.

[26]  Mark Lutz,et al.  Learning Python , 1999 .

[27]  R. D. Terzaghi.  Sources of Error in Joint Surveys , 1965 .

[28]  Jay A. Kreibich.  Using SQLite , 2010 .

[29]  Stefan M. Luthi,et al.  Toward a quantitative definition of mechanical units: New techniques and results from an outcropping deep-water turbidite succession (Tanqua-Karoo Basin, South Africa) , 2007 .

[30]  F. Reiter,et al.  Easy handling of tectonic data: the programs TectonicVB for Mac and TectonicsFP for Windows , 2002 .

[31]  T. V. Loudon,et al.  Geoscience after IT. Part B.: benefits for geoscience form information technology, and an example from geological mapping of the need for a broad view , 2000 .

[32]  Terry Engelder,et al.  Joint development during fluctuation of the regional stress field in southern Israel , 2001 .

[33]  Michele L. Cooke,et al.  Stratigraphic controls on vertical fracture patterns in Silurian dolomite, northeastern Wisconsin , 2003 .

[34]  David Hunt,et al.  Virtual fieldtrips for petroleum geoscientists , 2010 .

[35]  Andreas Bergmann,et al.  Object-oriented modeling of data sources as a tool for the integration of heterogeneous geoscientific information , 2001 .

[36]  John A. Hudson,et al.  Characterization and Interpretation of Rock Mass Joint Patterns , 1985 .

[37]  Stefan M. Luthi,et al.  Multi-scale fracture network analysis from an outcrop analogue: A case study from the Cambro-Ordovician clastic succession in Petra, Jordan , 2012 .

[38]  I. Trinks,et al.  Unlocking the spatial dimension: digital technologies and the future of geoscience fieldwork , 2005, Journal of the Geological Society.

[39]  John A. Howell,et al.  From outcrop to reservoir simulation model: Workflow and procedures , 2007 .