Impact of Kerogen Molecular Structure on Hydrocarbon Recovery: Tracing the Line of Death

Abstract

Today, shale gas contributes to more than 50% of total natural gas production in the United States. The major reason for such an increase in shale gas production are advancements in horizontal drilling and hydraulic fracturing technologies. Despite these technological advancements, multiple challenges still exist in shale gas production such as poor prediction of total gas in place (GIP), low gas recovery, and rapid decline in well productivity. One of the primary ways in which we can adress these challenges is by developing better uunderstanding of the molecular level properties of the shale organic matter, i.e., kerogen. In this study, molecular structural models of different kerogen samples with thermal maturity ranging from 0.8 to 3 VRo were developed using ¹³C solid-state Nuclear Magnetic Resonance (NMR) analysis. We also determine the heterogeneities present in the molecular structure of kerogen in a particular kerogen “type” (at similar maturity windows) not only in different basins but also within a particular shale basin. The impact of such heterogeneities on physicochemical properties of kerogen (and shale) such as its density, porosity, sorption capacity, fracture properties was evaluated. We also demonstrate how an understanding of molecular-level properties of kerogen can lead to better prospect evaluation, designing a better fracturing fluid composition and a better hydrocarbon recovery.

AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019