Abstract

Understanding basin temperature variations is important to hydrocarbon exploration and increasingly relevant to the growing geothermal energy and carbon capture utilization and storage (CCUS) businesses. However, the geothermal industry lacks the large sets of temperature data required to understand subsurface temperature. TGS has over 4.8 million wells in the major basins onshore USA and Canada; with digital log data for over 3.1 million wells. Using these well data, we developed a methodology to create basin temperature models (BTMs) that combine a geological layer model built with outcrop data and many thousands of formation tops interpreted from log data with large numbers (10,000s) of indexed and quality-controlled bottom-hole temperature (BHT) data. Borehole temperatures tend to equilibrate, increasing towards ambient formation temperature with elapsed time since final drilling fluid circulation. We use the maximum BHTs recorded in a layer (normalized for depth) or cell rather than a corrected average or regression-based model. Present day temperature volumes are constructed with two methodologies. We first define a lateral and vertical varying interval geothermal gradient (IGG) function that models the maximum envelope of the BHTs recorded for each major lithostratigraphic unit: the MaxG method. We then construct the MaxG temperature volume by stacking IGGs for all units in the basin. With sufficiently dense data, we use the maximum BHT in each cell of the volume: the MaxBHT method. BTMs for new areas can be created in 4 months. TGS has developed 18 BTMs (periodically updated) across North America, delivered in SEG–Y format as 3D temperature-depth cubes for easy integration with other data. Originally intended for hydrocarbon exploration, they also serve in re-purposing old hydrocarbon fields to geothermal uses. The BTM method is illustrated here with examples from our recently (2021) completed BTM of the Haynesville Play in Texas and Louisiana.