Biogenic coalbed methane (BCBM) reservoirs aim to produce methane from in situ coal deposits following microbial conversion of coal. Success of BCBM reservoirs requires economic methane production within an acceptable timeframe. The work reported here quantifies the findings of previously published qualitative work, where it was found that bioconversion induces strains in the pore, matrix and bulk scales. Using imaging and dynamic strain monitoring techniques, the bioconversion induced strain is quantified here. To understand the effect of these strains from a reservoir geomechanics perspective, a corresponding poromechanical model is developed. Furthermore, findings of imaging experiments are validated using core-flooding flow experiments. Finally, expected field-scale behavior of the permeability response of a BCBM operation is modeled and analyzed. The results of the study indicated that, for Illinois coals, bioconversion induced strains result in a decrease in fracture porosity, resulting in a detrimental permeability drop in excess of 60% during bioconversion, which festers itself exponentially throughout its producing life. Results indicate that reservoirs with high initial permeability that will support higher Darcian flowrates, would be better suited for coal bioconversion, thereby providing a site-selection criteria for BCBM operations.

生物煤层气（BCBM）储层旨在通过煤炭的微生物转化从原位煤矿床中生产甲烷。 BCBM 储层的成功需要在可接受的时间范围内经济地生产甲烷。这里报告的工作量化了先前发表的定性工作的结果，其中发现生物转化会在孔隙、基质和块体尺度中引起应变。使用成像和动态应变监测技术，生物转化引起的应变在这里被量化。为了从储层地质力学的角度理解这些应变的影响，开发了相应的孔隙力学模型。此外，成像实验的结果通过岩心驱流实验得到了验证。最后，对 BCBM 作业的渗透率响应的预期现场规模行为进行了建模和分析。研究结果表明，对于伊利诺伊州煤来说，生物转化引起的应变会导致裂缝孔隙度下降，导致生物转化过程中渗透率下降超过 60%，这是有害的，在整个生产寿命中，渗透率会呈指数级恶化。结果表明，具有高初始渗透率的储层将支持更高的达西流量，更适合煤生物转化，从而为 BCBM 作业提供选址标准。