Application of Innovative Technologies to Fractured Devonian Shale Reservoir Exploration and Development Activities

Abstract

This project was conducted under the auspices of NYSERDA contract 4881-ERTER-ER-99 with its primary purpose to obtain and utilize "ground-truth" data collected from two Upper Devonian Shale wells. With this information, a better understanding of the productive potential in western New York has been obtained. Both wells (W. Stein Unit #2 and S. Preston #8) were drilled in August 2001 by Great Lakes Energy Partners, LLC and are located in Athens field, Crawford County, Pa. adjacent to the Tyrone Mount Union lineament. The wells were completed open hole without any stimulation. Numerous technologies were used to acquire this information including running geophysical logs, gas sample analysis, and examining ten rotary sidewall cores from the Stein Unit #2. From this data, various models were built to characterize geologic, reservoir, and fluid flow characteristics, which were used to estimate gas in place, bulk permeability, and deliverability. Though the existent natural fracture systems provide conduits from the reservoir to the wellbore, the shale in this area contains only a limited quantity of gas-in-place and is exceptionally lean in organic content. Permeability studies indicate this is a dual porosity system producing primarily via the fractures, and to a lesser extent from the matrix. Very little adsorption of gas is present and the reservoir is relatively low in organic content. An analysis conducted by the University of Michigan reveals that the gas is primarily thermogenic in origin with possible traces of biogenic origin. The results of this paper are significant in that it provides a better understanding of the production mechanisms of the reservoir within a localized area. Based on the results of this study, the following conclusions are provided:The Upper Devonian Shale in this immediate area is extremely lean in organic content as indicated by its low Total Organic Carbon (TOC) = 0.36%. As a point of reference, many productive shales have TOC values ranging from 1–9%.Shales in this immediate area are a limited source of hydrocarbons (~27 Mscf per acre-foot).The gas is thermogenic with trace amounts of biogenic origin.Very little adsorption of gas is present.Both test wells are located in an area of natural fracturing adjacent to the Tyrone Mount Union lineament, which most likely provides a conduit for natural gas production.Relative to other producing shales, the reservoir is comparatively poor near the test wells.Production data analysis indicates a dual porosity system producing primarily through fractures and to a lesser extent, via the matrix.Estimated ultimate recoveries range from 1.1 to 3.0 MMscf, and drainage areas are 1.325 and 2.0 acres for the Preston #8 and Stein Unit #2 respectively, assuming no stimulation.

Application of R/S analysis in fracture identification of shale reservoir of the Lower Cambrian Niutitang Formation in northern Guizhou Province, South China

“…R/S analysis based on conventional logging is an accurate and efficient fracture identification method, which provides a new idea for the study and quantitative characterization of the natural fractures in shale reservoirs. KEYWORDS fracture identification, natural fractures, R/S analysis, shale reservoir, well logging 1 | INTRODUCTION Shale reservoirs are characterized by low porosity, low permeability, and poor physical properties, which make it difficult to obtain industrial gas flow in a natural state (Curtis, 2002;Ding et al, 2015;Li et al, 2016;MacDonald, Frantz, & Merriam, 2003). The development of natural fractures not only improves the reservoir conditions of shale but also provides favourable conditions for forming large-scale fracture networks during hydraulic fracturing.…”