The Reservoir Characterization Lab (RC.Lab) performs studies on siliciclastic and carbonate lithologies on fundamental processes of structural diagenesis with applications to geothermal, storage, and exploration scenarios. Our main methods include:

Results are integrated for rock typing, predictive data science applications, diagenetic forward modeling, and static/dynamic reservoir models.

We develop machine learning workflows to optimally assess produced geodata and samples from surface to subsurface environments and employ experimental datasets to supplement classical descriptive geological workflows on mineral precipitation and dissolution. These datasets and experimental results are combined with digital material sciences and engineering to improve dynamic 3D microstructure modelling capabilities. 

Completed PhD projects

Jasemin A. Ölmez Link

Jonas Greve Link

Felix Allgaier Link

Olajide J. Adamolekun Link

Christina Schmidt Link

Alexander C. Monsees Link

Ivy Becker Link

Highlights

Machine learning-based prediction of petrophysical properties

Based on in-house studies we set up machine learning models to predict petrophysically measured porosity and permeability data based on petrographic point-counting data. We extended these models with published data from available wells (51 in total) and can assess porosity and permeability within reasonable errors for practical reservoir characterization. This will in future enable more detailed assessments of petrophysical reservoir properties along entire well sections in siliciclastic reservoirs based on readily produced cuttings.

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Fractured Carbonates

We assess fractured carbonate reservoir quality based on core material, image logs, digital and manual fracture measurements, UAV-assisted aerial images, integrated with petrographic analyses and petrophysical measurements at reservoir confining pressures. Partially sealed fractures/veins maintain higher reservoir quality even at elevated confining stresses of up to 30 MPa and highlight that microstructure assessments are required in concert with Td/Ts evaluations to capture all relevant producing fracture orientations. Fracture clustering analyses also highlight locally statistically higher fracture intensities can be observed away from fault zones in limestones. Aerial images of fractured bedding planes inform on fracture connectivity and can imply suitable fluid conduits. Correlation of surface to subsurface datasets ensure applicability of results to real-world problems, via core-to-image log correlation and image log interpretation.

Cuttings

Cuttings are produced at every well site, but are rarely utilized aside from checking drilling progress. We assessed rock compositions and vein microstructures from a turbiditic sequence and could highlight that a combination of petrographic, geochemical, and geophysical data can highlight producing intervals. Reservoir quality is mostly governed by partially sealed fractures/veins, whose microstructure is still discernable in cuttings of similarly composed host lithologies.

Sandstone Reservoir Quality

Reservoir quality in sandstones is governed by the diagenetic and burial history in sedimentary basins, which are the past and future for energy and heat production. Temperatures, fluids, and effective stresses acting on the sandstones govern compaction, cementation, dissolution, and fracturing, which in turn affect porosity and permeability. High resolution outcrop and core-based studies are integrated with field-based studies in active depositional systems to assess sedimentary, diagenetic, and granulometric controls on key petrographic properties, as µm-thin clay mineral grain coatings. Grain coatings have been shown to affect cement precipitation and can enhance chemical compaction, thereby impacting the development of reservoir quality over geological timescales. Integration of these processes lead to better diagenetic forward models and enhance our understanding of subsurface reservoir systems.

Structural diagenesis

Structural diagenetic studies focus on a holistic view of the interaction of structural and diagenetic processes in sedimentary rocks. Fracture precipitates, bridging cements, maintaining porosity and permeability in reservoir rocks, and relative age relationships are studied to gain an in depth understanding on fluid pathways in the subsurface. Flow-through experiments at elevated pressures and temperatures shed light into fluid-rock interactions and how sedimentary rock compositions affect precipitation sites and sizes of cement overgrowths on fracture surfaces.

Permeability

Temperature, confining stresses, time, and different gases/fluids affect permeability in rocks. With a focus on cap rocks for e.g., CO₂ sequestration the petrophysical measurements with a duration of up to weeks can shed a light into lithology or region-specific rock properties to support a data-driven discussion on optimal storage sites. Furthermore, these experiments are the foundation to calibrate digital rock models of metamorphic, crystalline and sedimentary rocks. 

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