Gasgenese und Gasspeicherung im flözführenden Oberkarbon des Ruhr-Beckens

The present study investigates the generation, accumulation and occurrence of coalbedmethane (CBM) in the Ruhr Basin. It was triggered by a commercial CBM project performedjointly by DEUTSCHE STEINKOHLE AG (formerly RUHRKOHLE AG), RUHRGAs AG andCONOCO MINERALOEL GmbH. The aim of the project was to explore the CBM potential ofUpper Carboniferous strata and to evaluate the commercial producibility of CBM from suchreservoirs. This study provides a knowledge-based exploration model to delineate areas withpotentially high gas content. It also provides data for a more reliable quantification of suchreservoirs already at an early stage of exploration, prior to costly drilling operations.In order to quantify the gas generation potential in the Upper Carboniferous the amount oforganic matter both in coal seams and in dispersed form was estimated (214m$^{3}$/m$^{2}$area). Boththe maximum net coal thickness and the highest accumulation of dispersed organic matter(210 kg$_{OM}$/m$^{3}_{rock}$) occur in the Westphalian B 1. The total quantity of organic matter in thesediments of the Ruhr Basin (10.000 km$^{2}$) amounts to approximately 2.4$\cdot$10$^{9}$ t. According to amass-balanced gas generation model one ton of terrestrial organic matter generates, within amaturity interval of 0.65 to 2.7 %VR$_{r}$, approximately 153 m$^{3}$ methane, 81m$^{3}$ carbon dioxideand 5 m$^{3}$ nitrogen (STP). When applied to the amount and maturity of the organic matter inthe Ruhr Basin this corresponds to a total gas generation of 17.600 m$^{3}_{Gas}$/m$^{2}_{area}$. The UpperWestphalian A2 has been the most productive stratigraphic interval (10.4 m$^{3}_{Gas}$/m$^{3}_{rock}$). Theportion of methane in the cumulative gas liberated from the organic matter rises withincreasing depth and maturity of the organic matter to a maximum of 65 Vol.% in Namur Ccoals. Also, gas generation from terrestrial OM was studied both by means of non-isothermalopen-system pyrolysis and - for the first time - by on-line Pyrolysis-GC-IRMS. For fivepyrolysis products studied with this method the experiments illustrate a strong isotopefractionation and local isotopic maxima and minima.The gas storage in coal seams was studied using a newly designed high pressure/hightemperature adsorption device. The data of more than fifty experiments at pressures of up to20 MPa and maximum temperatures of 175 °C showed an increase of adsorption capacitywith increasing pressure, and decreasing temperature and moisture content. Measurements ofthe specific surface area (CO$_{2}$) gave highest values for vitrain (vitrinite-rich samples).Generally, smaller-than-average surface areas were observed within a maturity range of 1.0 to1.4 %VR$_{r}$. Based on the experimental data correlations were established that can be used tomodel the depth dependence of the adsorption capacity of the organic matter. The proposeddynamic sorption model links experimental results to the geological evolution of sedimentarybasins by relating phases of tectonic uplift and subsidence to adsorption/desorption events atdifferent depth intervals. Thus, the model provides a new interpretation for the accumulationand regional distribution of CBM reservoirs in the context basin evolution.The occurrence of CBM in the Ruhr Basin was examined both in a thorough geochemical andisotopic study of two exploration wells and also by evaluating exploration data of the local [...

Gasgenese und Gasspeicherung im flözführenden Oberkarbon des Ruhr-Beckens

The present study investigates the generation, accumulation and occurrence of coalbedmethane (CBM) in the Ruhr Basin. It was triggered by a commercial CBM project performedjointly by DEUTSCHE STEINKOHLE AG (formerly RUHRKOHLE AG), RUHRGAs AG andCONOCO MINERALOEL GmbH. The aim of the project was to explore the CBM potential ofUpper Carboniferous strata and to evaluate the commercial producibility of CBM from suchreservoirs. This study provides a knowledge-based exploration model to delineate areas withpotentially high gas content. It also provides data for a more reliable quantification of suchreservoirs already at an early stage of exploration, prior to costly drilling operations.In order to quantify the gas generation potential in the Upper Carboniferous the amount oforganic matter both in coal seams and in dispersed form was estimated (214m$^{3}$/m$^{2}$area). Boththe maximum net coal thickness and the highest accumulation of dispersed organic matter(210 kg$_{OM}$/m$^{3}_{rock}$) occur in the Westphalian B 1. The total quantity of organic matter in thesediments of the Ruhr Basin (10.000 km$^{2}$) amounts to approximately 2.4$\cdot$10$^{9}$ t. According to amass-balanced gas generation model one ton of terrestrial organic matter generates, within amaturity interval of 0.65 to 2.7 %VR$_{r}$, approximately 153 m$^{3}$ methane, 81m$^{3}$ carbon dioxideand 5 m$^{3}$ nitrogen (STP). When applied to the amount and maturity of the organic matter inthe Ruhr Basin this corresponds to a total gas generation of 17.600 m$^{3}_{Gas}$/m$^{2}_{area}$. The UpperWestphalian A2 has been the most productive stratigraphic interval (10.4 m$^{3}_{Gas}$/m$^{3}_{rock}$). Theportion of methane in the cumulative gas liberated from the organic matter rises withincreasing depth and maturity of the organic matter to a maximum of 65 Vol.% in Namur Ccoals. Also, gas generation from terrestrial OM was studied both by means of non-isothermalopen-system pyrolysis and - for the first time - by on-line Pyrolysis-GC-IRMS. For fivepyrolysis products studied with this method the experiments illustrate a strong isotopefractionation and local isotopic maxima and minima.The gas storage in coal seams was studied using a newly designed high pressure/hightemperature adsorption device. The data of more than fifty experiments at pressures of up to20 MPa and maximum temperatures of 175 °C showed an increase of adsorption capacitywith increasing pressure, and decreasing temperature and moisture content. Measurements ofthe specific surface area (CO$_{2}$) gave highest values for vitrain (vitrinite-rich samples).Generally, smaller-than-average surface areas were observed within a maturity range of 1.0 to1.4 %VR$_{r}$. Based on the experimental data correlations were established that can be used tomodel the depth dependence of the adsorption capacity of the organic matter. The proposeddynamic sorption model links experimental results to the geological evolution of sedimentarybasins by relating phases of tectonic uplift and subsidence to adsorption/desorption events atdifferent depth intervals. Thus, the model provides a new interpretation for the accumulationand regional distribution of CBM reservoirs in the context basin evolution.The occurrence of CBM in the Ruhr Basin was examined both in a thorough geochemical andisotopic study of two exploration wells and also by evaluating exploration data of the local [...

Haldengeothermie - Chancen und Risiken bei der thermischen Nutzung von Haldenschwelbränden

Mining spoil heaps are common in coal-mining areas. A little-known fact that has not yet attracted much public attention is the phenomenon of smouldering inside heaps. The energetic utilization of smouldering waste heaps is being investigated as part of a joint research project funded by the BMBF. Three borehole heat exchangers were installed in a spoil heap in the western Ruhr. It can be shown that the flow temperatures and thus the achievable heat extraction rate are much higher than in conventional geothermal systems. In order to determine the thermal and physical properties of the mining materials, several field and laboratory tests were performed. The variation of the properties of the inhomogeneous material is much less than expected. When working on old mining waste heaps, many challenges have to be faced but the high energetic potential justifies the efforts