A catalog of porosity and permeability from core plugs in siliciclastic rocks

Abstract

Porosity and permeability measurements on cored samples from siliciclastic formations are presented for 70 data sets, taken from published data and descriptions. Data sets generally represent specific formations, usually from a limited number of wells. Each data set is represented by a written summary, a plot of permeability versus porosity, and a digital file of the data. The summaries include a publication reference, the geologic age of the formation, location, well names, depth range, various geologic descriptions, and core measurement conditions. Attributes such as grain size or depositional environment are identified by symbols on the plots. An index lists the authors and date, geologic age, formation name, sandstone classification, location, basin or structural province, and field name. Introduction Porosity and permeability measurements are frequently made on plugs extracted from core from wells drilled for oil and gas exploration. The data are valuable for linking permeability, a quantity not directly measured with well logs, to porosity, a quantity which is routinely determined with well logs. The definitions of porosity and permeability and methods of laboratory measurement can be found in such references as American Petroleum Institute (1956, 1960), Bass (1987), Dullien (1979), and Hearst and others (2000). This report presents a catalog of porosity and permeability data, along with geological and location information, taken from sources in the open literature. The compilation is restricted to measurements on core plugs in conglomerates, sandstones, siltstones, and shales. An explorationist may want to select an analog from the catalog in order to infer the permeability and porosity of a particular reservoir of interest. The catalog can also be used for general studies of porosity and permeability in the subsurface. For this compilation, the ideal data set has the following attributes: (1) a minimum of 20 values spanning a range of porosity and permeability, (2) core plugs sampling a specific geologic formation, preferably from a small number of wells, (3) a referenceable source, (4) formation name, age of formation, depth, and location, (5) a description of the depositional setting, (6) petrological description including grain size, primary minerals, and diagenetic minerals, and (7) method of measurement. The presence of hydrocarbons was not a criterion. Few data sets met all these criteria. Permeability and porosity data are found in the geological, petrophysical, and petroleum engineering literature. The supportive descriptions of the samples vary greatly according to the nature of the study being reported. Different papers variously report grain size and sorting, sandstone classification, facies classification, lithology, clay content, or depositional environment. Petrological observations may be reported at length or not at all. Some authors focus on reservoir quality, and porosity and permeability are discussed at length. In other papers, porosity and permeability data are presented with little explanation. Data sets were