Tight gas sandstones (TGS) represent 72% (342 Tcf) of the projected unconventional resource (474 Tcf) for the United States. Rocky Mountain tight gas sandstones representing 70% of the total TGS resource base (241 Tcf; USEIA, 2004) and Mesaverde Group tight gas sandstones represent a principal gas productive unit in Western U.S. basins including the basins that are the focus of this project (Washakie, Uinta, Piceance, Upper Greater Green River, Wind River). Industry assessment of the regional gas resource, projection of future gas supply, and exploration programs require an understanding of the reservoir properties and accurate tools for formation evaluation of drilled wells. The goal of this project is to provide petrophysical formation evaluation tools related to relative permeability, capillary pressure, electrical properties and algorithm tools for wireline log analysis. Detailed and accurate moveable gas-in-place resource assessment is most critical in these marginal gas plays and there is need for quantitative tools for definition of limits on gas producibility due to technology and rock physics and for defining water saturation.
Tasks involved with meeting the project objectives include clarification and review of the research plan (Task 1), initial technology assessment (Task 2), collection and consolidation of published advanced rock properties data into a publicly accessible relational digital database and collection of at least 300 rock samples and digital wireline logs from 4-5 wells each from five basins that will represent the range of lithofacies present in the Mesaverde Group in these basins (Task 3). Basic properties (including routine and in situ porosity, permeability, and grain density) of these rocks will be measured and, based on these properties, 150 samples will be selected to represent the range of porosity, permeability, and lithofacies in the wells and basins (Task 4.1). Measurements to be performed on these selected samples comprise: 1) Drainage critical gas saturation (4.2), Routine and in situ mercury intrusion capillary pressure analysis (4.3), cementation and saturation exponents and cation exchange capacity using multi-salinity method (4.4), geologic properties including core description, thin-section microscopy, including diagenetic and point-count analysis (4.5), and standard wireline log analysis (4.6). The compiled published data and data measured in the study will be input to an Oracle database (5.1). XML code will be written that will provide web-based access to the data and will allow construction of rock catalog format output sheets based on user-input search and comparison criteria. The data will also be available as a complete Oracle database (5.2). Core and wireline log calculated properties will be compared and algorithms developed for improved calculation of reservoir properties from log response (Task 6). To evaluate the scale dependence of critical gas saturation bedform-scale reservoir simulation models will be constructed that represent the basic bedform architectures present in the Mesaverde sandstones. Simulations will be performed that will parametrically analyze how critical gas saturation and relative permeability scale with size and bedding architecture (Task 7). An active web-based, publication, and short-course technology transfer program will be performed (Task 8).
This project represents a two-year collaboration of the Kansas Geological Survey at University of Kansas and The Discovery Group, Inc. The projects requests $411,030 of US Department of Energy funds over two years to support the program and technology transfer activities.