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Geothermal field interpretation in south‐central Kansas for parts of the Nemaha Anticline and flanking Cherokee and Sedgwick basins
Author(s) -
Förster ANDREA,
Merriam DANIEL F.
Publication year - 1993
Publication title -
basin research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.522
H-Index - 83
eISSN - 1365-2117
pISSN - 0950-091X
DOI - 10.1111/j.1365-2117.1993.tb00068.x
Subject(s) - geothermal gradient , geology , temperature gradient , thermal conductivity , geothermal exploration , basement , outcrop , sedimentary rock , anticline , borehole , field (mathematics) , sediment , mineralogy , geomorphology , petrology , geophysics , geothermal energy , structural basin , geochemistry , geotechnical engineering , thermodynamics , physics , civil engineering , mathematics , pure mathematics , engineering , quantum mechanics
The first assessment of temperature conditions in Kansas was made by geothermal gradient computations from temperature measurements in shallow boreholes, and these conditions are related to structural patterns, sedimentary cover and underlying basement properties. The area of south‐central Kansas was selected for detailed study of geothermal character in relation to the geology. The aim was to quantify the relations and to determine the relationship of different variables of the temperature field. Input parameters included geothermal variables of gradient and temperature, and structure and sediment thickness. Two approaches were used: (1) the numerical computation of theoretical temperature‐depth models based on conductive heat transfer, and (2) a map‐comparison technique based on algebraic methods. The temperature field information usable for the map comparison is different in response to different measurements (nonequilibrium BHTs and temperatures from logged measurements in equilibrium). Derived from modelled results (plotted isotherms on cross‐sections), a close relation between gradients and thermal conductivity of the sediments was confirmed. The most noticeable effect on the geothermal field, as noted quantitatively from the map‐comparison study, is the relation of thickness of outcropping Permo‐Pennsylvanian units because of their different thermal conductivity. The eastward increase of mean gradients is inversely related to the total sediment thickness, but this is mostly recognizable using the shallow temperature gradients. This dissimilarity gives additional evidence for a close link between gradients and thermal conductivity of the sediments in which the temperature measurements were made. The effect caused by the structure in deeper (older) units is not important and seems not to be significant, nor is the influence of the basement rock composition as indicated by the temperature modelling.