Thermodynamics and heat transfer in a CO2 injection well using distributed temperature sensing (DTS) and pressure data

Based on distributed temperature sensing (DTS) and pressure data well bore thermodynamics and heat transfer are determined for the CO2 injection well in Ketzin, Germany. The DTS signal is decomposed in two components, a mean value and a spatial derivation. The mean value and the pressure data are the basis for a thermodynamically phase state calculation. The derived heat transfer is of high accuracy for shallow depth but the sensitivity to measurement errors increases for deeper parts of the well when the phase change becomes isentropic. These limitations are compensated by a new evaluation of DTS signals. The derivation of the DTS signal is proportional to the radial heat flux. The proportionality factor is calibrated under conditions when the thermodynamic method provides accurate results. The combination allows to determine heat transfer for all operational conditions and the entire well. The analyses is used to determine thermodynamics, maintain stable injection conditions and may be applied for minimising the heating energy.