The Transport Properties and Fracture Physics Research Laboratories at the BGS are led by Caroline Graham and Robert Cuss, respectively, and are part of the Fluid and Rock Processes Laboratory Cluster. Research in the Transport Properties Research Laboratory (TPRL) and the Fracture Physics Laboratory (FPL) focuses on understanding the mechanisms and processes governing the movement of fluids (water, gas and solutes) and the deformation of rock in the subsurface, specialising in the measurement of properties in ultra-low permeability materials. Thirty years of development in this field has led to high-precision techniques, allowing exceptionally small amounts of flow to be measured where conventional techniques can be unsuccessful. As such, the TPRL and FPL are able to investigate the long-term properties of rocks that act as ‘seals’ to fluid, on geological timescales.

Laboratory capability

With careful attention to experimental design, choice of instrumentation, calibration and regulation of testing conditions, the laboratories are able to quantify key properties for intact, fractured and flow along interfaces for low permeability materials.

• Apparatus and experimental methodologies are custom designed to meet the precise requirements of the client and work programme.
• Experiments can be performed on intact or fractured rock, as well as interfaces between neighbouring materials.
• Experiments are performed under simulated downhole stress, pore pressure, temperature, and chemical conditions using triaxial, isotropic (hydrostatic) or constant-volume cells.
• High accuracy, heavy duty shear box systems have been developed to examine fracture, fault and interfacial flow.
• Apparatus is assembled in a constant temperature test chamber, which is regulated to better than ±0.3°C or within oven or high-precision incubators.
• pressure and flow-rates are precisely set or monitored using microprocessor-controlled syringe pumps
• Experiments are remotely controlled and test parameters recorded using customised code developed using the National Instruments LabVIEW software package.

Measured properties

• saturation and consolidation properties
• intrinsic permeability (including specific storage and anisotropy ratio)
• coupled flow parameters (e.g. osmotic permeability, consolidation coefficients)
• gas diffusion coefficients
• capillary entry breakthrough and threshold pressures
• gas permeability function
• drained and undrained compressibility
• rheological (creep) properties
• mechanical properties

Research interests

Laboratory and field studies

Laboratory capability

Laboratory research is conducted on samples up to 250 cc in size; these represent large test samples in low permeability materials. Tests can be conducted rapidly (in minutes), but our main emphasis is on long-term experiments that can run for multiple years. However, test durations of six months to one year are normal.

The laboratory has six isotropic, four constant volume, three shear rigs, and three triaxial apparatus. These cover stress conditions from 1 to 70 MPa (near surface to 3 km depth). The laboratory also has a high-pressure capability, which is able to extend the pressure range to 150 MPa (at 130°C) using an isotropic cell to explore flow and deformation behaviour at near-crustal depths.

The laboratory is also equipped with a number of hydraulic presses able to consolidate and condition-test material, or create synthetic samples for process understanding and material design. Pressures in excess of 500 MPa (on samples 60 mm in diameter) can be applied by the presses to yield materials with a range of material properties.

The TPRL has an established track record of the design, build and operation of field-scale investigations. These include the Lasgit experiment at the Äspö Hard Rock Laboratory (Sweden; 2005–2020), the gas transfer experiment at the Mont Terri Underground Research Laboratory (Switzerland: 2020–2022), and the cavern formation experiment at the Dark Matter Laboratory at the Boubly Potash mine (UK: 2019 onwards).

Further information

Hydrothermal research at the BGS is carried out within the Fluid and Rock Processes Laboratory Cluster. This laboratory is used to study chemical reactions between fluids and rocks under conditions found in the top few kilometres of the Earth’s crust. In more than 25 years of operation, the laboratory has been at the centre of numerous investigations that require well-controlled conditions to study reaction processes under in situ conditions (i.e. elevated temperatures and pressures) and it is probably unique in the range of very different studies that have been investigated in the laboratory.

The laboratory

Relevance to important issues

Experiments produce data relevant to important issues of today:

• studying the high temperature alteration of borosilicate glass, an important waste-form being considered for the for disposal of high-level radioactive waste
• investigating the reactions occurring in and around highly alkaline cement, with a view to understanding alkaline disturbed zones around repositories for the underground disposal of low to intermediate radioactive waste
• quantifying the reactivity of CO₂Ìýwith rocks and its impact on long-term mineral trapping during the deep underground disposal of CO₂
• studying reactions occurring within high-temperature geothermal systems and their potential impact on rocks and reservoir properties
• investigating weathering processes, including the leaching of toxic metals from fly ash and mine wastes
• quantifying the dissolution rates of a variety of minerals in order to help improve the accuracy and confidence in predictive geochemical computer models

Carbon capture and storage research

These are the areas of carbon capture and storage (CCS) research that this laboratory is working on.

Our staff

The Hydrothermal Laboratory staff all have an academic chemical background, as well as strong practical skills. Properly understanding the processes going on in the experiments involves close collaboration between the experimental staff, analytical chemists and mineralogists, as well as collaboration with other BGS fluid processes researchers:

• Gas Monitoring Facility: Helen Taylor-Curran
• Geomicrobiology Laboratory: Simon GregoryÌý
• Hydrates and Ices Laboratory: Chris Rochelle
• Transport Properties Research Laboratory: Caroline Graham

Geomicrobiology research at the BGS is led by Simon Gregory and is carried out within the Fluid and Rock Processes Laboratory Cluster. Most of our work addresses issues relevant to decarbonisation and resource management, where we investigate microbiological processes associated with geological materials and how they impact the environment. Our particular interests lie in the positive or negative impact that microorganisms can have on subsurface industries.

Laboratory capability

The laboratory is well equipped for a wide range of culture-based microbial techniques as well as molecular microbiological methods. We have considerable experience in constructing and running experiments designed to replicate the pressures and temperatures found at depth in the subsurface.

Our facilities include:

• pressure vessels and pumps for running experiments at elevated pressures and temperatures
• a microaerophilic/anaerobic chamber for cultivation of oxygen-sensitive microorganisms
• FerMac 200 series modular bioreactor
• PCR, qPCR and nanopore sequencing facilities
• microplate reader used for growth and chemical assays
• range of programmable incubators (-10–70ºC)

Our work

Methane in soils and groundwater

Microorganisms that consume methane (CH₄) respond rapidly to CH₄ emissions. We are trying to understand the response of microbes that consume CH₄ and other alkanes to determine whether they can be used to identify whether the CH₄ is from biological or geological sources. The organisms capable of consuming alkanes may also display behaviours that are beneficial to the bioremediation of a vast number of contaminants, which we are beginning to explore.

• methanotrophs in soils: what is the potential for microbial mitigation of methane leakage from soils?
• methanotrophs in groundwater

 

Biomining

Microorganisms can be used to extract a range of metals from ores and may provide more sustainable mining techniques. Much of our research is targeted at understanding how microorganism can be harnessed to extract and separate rare earth elements, initially from ion adsorption clays. We are expanding our biomining research to other ores and other critical metals.

• SoSRARE

 

Other research

We are increasingly involved in other areas of BGS and external research, including:

• detection and enumeration of pathogens in groundwater
• microbiology of geothermal heating systems
• methanogenesis
• developing SEM based microbial imaging techniques

The BGS Hydrate and Ices Laboratory is a specialised facility that has been used for 10 years to study the behaviour of gas hydrates within sediments.

What are gas hydrates?

Hydrates are a subgroup of a range of compounds called clathrates and have water molecule ‘cages’. A wide range of gases and low boiling point liquids can fit in the cages, including methane and carbon dioxide. They are usually white, ice-like solids that are stable at low temperatures and high pressures (e.g. deep oceans, or below permafrost in polar regions).

How do we study gas hydrates?

The laboratory contains a variety of temperature-controlled equipment and pressure vessels capable of maintaining controlled, experimental conditions representative of temperatures and pressures typical the seabed of deep seas or below permafrost. As well as the equipment in which gas hydrates can be formed, the laboratory also undertakes cryogenic scanning electron microscopy (cryo-SEM) and cryogenic X-ray diffraction (cryo-XRD), both of which are capable of analysing cryo-preserved samples of hydrates/ice.

Laboratory capabilities

Laboratory capabilities include:

• synthesis of CO₂ and methane hydrate as solid hydrates and as sediment-hosted hydrates in a variety of lithologies
• simulation of permafrost through freezing wet sediments
• pressure/temperature cycling and dissociation studies of hydrates and ice
• geophysical measurements on hydrates and frozen sediments
• resistivity logging using non-contact methods and internal resistivity determination
• determination of acoustic properties (Vp and Vs) of hydrates and frozen sediments

Areas of investigation

These are some of the areas of investigation in which the laboratory and associated facilities have been involved.

CO₂ hydrate in deep-water sediments

The formation of CO₂ hydrate in cool, moderately deep-water marine sediments is a fairly novel method for underground CO₂ storage but offers certain advantages in terms of geochemical trapping mechanisms. The conditions and reactions we study are quite different to those in more conventional CO₂ storage schemes, where conditions are warmer and where free CO₂ exists as a supercritical fluid. Storage areas of interest are:

• as liquid CO₂ with a hydrate cap above a relatively shallow reservoir
• the formation of CO₂ hydrate as a secondary trapping mechanism should CO₂ migrate out of a much deeper reservoir

Seabed core material

We study seabed core material to elucidate the relationship between natural methane hydrate and the sediment that hosts it, as well as the process of hydrate breakdown during warming and depressurisation.

Planetary science

We study hydrate and ice breakdown under low pressure/temperature conditions that are representative of those on Mars.

Equipment capabilities

Our equipment capabilities have recently been enhanced by a major refit of the laboratory and now include:

• a 3Ìý×Ìý3Ìý×Ìý2.4Ìým cold room capable of maintaining stable temperatures from -20°C to +10°C
• a large (1200Ìýlitre) cooled incubator capable of maintaining stable temperatures from -10°C to +50°C
• a medium-sized (600Ìýlitre) cooled incubator capable of maintaining stable temperatures from -10°C to +50°C
• a small (1200Ìýlitre) cooled incubator capable of maintaining stable temperatures from -10°C to +50°C
• other fridges, freezers and chiller units can maintain a range of low temperatures as required

A range of equipment can be placed into the incubators or cold room as required. This includes physical testing equipment, electronic sensors or pressure vessels. The latter range in size from approximately 1–12 litres. Many items of equipment in the lab have been manufactured within BGS workshops and it is possible for us to construct specialised equipment for specific studies.