Source rock geochemical assessment and estimation of TOC using well logs and geochemical data of Talhar Shale, Southern Indus Basin, Pakistan

Abstract

Assessment of organic carbon content (TOC) by geophysical logs has been a challenging task in the formation evaluation of shale gas. This research is conducted to estimate the unconventional hydrocarbon (shale-gas) potential of Talhar Shale in the Southern Indus Basin (SIB), Pakistan. In this study, total organic carbon content (%) was estimated through well logs by different methods and then correlated with well cuttings/core data to determine the best method for estimation of TOC content especially when well cuttings/core data are not available. The Talhar Shale’s thermal maturity, as well as the organic content, were assessed from geochemical analyses. Talhar Shale of Dangi-01 well has good to very good source potential whereas Chak7A-01 well has fair-good. According to Ven Krevalen cross-plot, Talhar Shale of Dangi-01 well has type III kerogen; it can only produce gas while Chak7A-01 has type II/III kerogen which produces both oil and gas. The TOC was estimated using two methods i.e., Schmoker’s and Hester’s and Multivariate Fitting methods. The estimated TOC is then correlated with well cuttings data and concluded that the Multivariate Fitting method is selected as an optimized method for estimation of TOC because it shows strong correlation values of 0.93 and 0.91 in both wells respectively for Talhar Shale SIB, Pakistan.

Geomechanical assessment of the Lower Turonian AR-F limestone Member, Abu Gharadig Field, Egypt: Implications for unconventional resource development

“…Since this is not the primary producer (i.e., zone of interest in terms of conventional reservoir pool), usually sonic logs were not recorded in the majority of the wells. Even in older wells, log data is unavailable for this interval, although organic geochemical characterization had been done on the AR-F cores and cutting samples from a few older wells (e.g., Abdel-Fattah et al, 2022;Khalil Khan et al, 2022). Availability of logs as well as laboratorymeasured rock strength, and elastic properties are critical for any geomechanical analysis.…”

Geochemical Evaluation of Paleocene Source Rocks in the Kohat Sub-Basin, Pakistan

“…This system involves accumulating, transforming, and migrating organic matter into a reservoir over sufficient geologic time and under proper burial depth and temperature–pressure conditions. The economic viability of a petroleum system depends on factors such as the quality, quantity, and type of petroleum present. − The search for oil focuses on identifying porous and permeable formations, commonly called source or reservoir rock. The first stage of the exploration process involves geochemical evaluation of the source rock.…”

Total Organic Carbon Determination by 13C CP/MAS Solid-State NMR in Unconventional Oil/Gas Source Rocks: A Case Study from the Neuquén and Cuyo Basins in Argentina

“…Rock richness is measured as the total organic carbon content of the rock (% TOC) and is a basic parameter to assess the generation potential, when considered together with thermal maturity. 1 The %TOC is usually measured by direct combustion (LECO method) or by programmed pyrolysis (Rock-Eval pyrolysis). 2 Both techniques have their advantages and disadvantages.…”

“…The main parameters necessary to characterize organic matter (OM) in a source rock are the type and quality of kerogen, OM richness, and thermal maturity. Rock richness is measured as the total organic carbon content of the rock (%TOC) and is a basic parameter to assess the generation potential, when considered together with thermal maturity . The %TOC is usually measured by direct combustion (LECO method) or by programmed pyrolysis (Rock-Eval pyrolysis) .…”