Abstract
The Upper Jurassic Haynesville Shale play covers an area extending through East Texas, northwest Louisiana and parts of southwest Arkansas. The true potential of this play as an unconventional play was largely unknown. Only after gas prices increased during the last decade oil companies started to see the Haynesville Shale as an economic shale gas play, despite its great depths of over 3000m. At present gas prices the Haynesville Shale is due to its depth once again of only marginal interest, however, in order to be prepared for renewed interest a fundamental understanding of the processes and timing controlling shale gas prospectivity is required.
In order to understand the variables of this unconventional play, we have identified the heat flow history as a critical control. Heat flow values and evolution through time can impact the critical timing of gas generation, secondary cracking of oil to gas, and oil and gas generation critical moments.
Using state of the art basin modeling software, a reconstruction of the heat flow history was performed. Predicted formation temperatures were calibrated against temperature data collected from 1644 wells drilled over the play.
Paleo-temperature evolution was calibrated against vitrinite reflectance data collected from 26 wells. Laboratory Rock-Eval analyses were utilized to assist in this study over 6 wells.
The area has been subjected to three major tectonic uplift events. After various simulation iterations we conclude that the heat flow increased slightly with each uplift event. This suggests that the uplift was accompanied by heat flow increase indicating a likely igneous control, which had a large impact on the heat flow history within the area. Such understanding proves to be vital in order to perform accurate hydrocarbon resource assessments.
