Whether it be a junior exploration company or a major producer, there are a couple of geological numbers that are essential for any Lithium brine venture. How much Lithium brine is available underground and how free it is to move, is information that could make or break a project.
Porosity tells us how much water a rock or soil can retain. Porosity is represented as a percentage. It is a very heterogeneous property. The range of values can vary from a few porosity units in old rocks to more than 50% in unconsolidated sediments and organic matter. The same bed or sediment layer will experience changes in total porosity and porosity network laterally as a result of the several factors related to sediment deposition and early diagenesis.
Permeability, on the other hand, is a measure of how easily water can travel through porous soil or bedrock. For a rock or halite to be permeable and for water to move through it, the pore spaces between the grains in the rock must be connected. Permeability is therefore a measure of the ability of a fluid to move through a substrate. Permeability is expressed in darcies or in fraction of a darcy. Hydraulic conductivity, which is closely related to permeability, is the measure of the ease with which water will pass through a substrate; defined as the rate of flow of water through a cross-section of one square metre under a unit hydraulic gradient at right angles to the direction of flow per unit of time (m/d).
Soil and loose sediments, such as sand and gravel, are porous and permeable. They can hold a lot of water, and it flows easily through them. Although clays are porous and can hold a lot of water, the pores in these fine-grained materials are so small that water flows very slowly through them. Clay has very low permeability, and for practical purposes they are usually considered as non-permeable.
So an exploration company or a production company is really interested in these concepts, as these will determine how much Lithium brine they will be able to extract from their resource.
Now every brinefield is different. In the Lithium Triangle, targets are associated with recent Salt Flats or “Salars”. They are mostly filled by a combination of lacustrine, fluvial and alluvial sediments but volcanic and volcaniclastic deposits are not uncommon. These sediment/rock properties are heterogeneous, vertically and laterally, making every salar unique, with different mixtures of sands, silts, clays, gravels, ash levels and other fallout deposits, ignimbrites and different evaporates. Lithium brine deposits are found at different depths throughout these deposits, with varying concentrations of brine at different levels. Above the brine, there are often sediments containing fresh water, being evident in on the surface by the abundance of plant and bird life.
It is essential to be able to know exactly where to place the filters on the production wells, and it is of upmost importance to avoid cross-contamination between brine and freshwater; firstly, for ecological reasons, but also for commercial reasons, as dilution of the brine is not desired at all. Identifying the most permeable layers and avoiding fresh water are essential to determine at what levels the filters are placed at. In order to make this determination, a selection of different technologies is currently employed across the “Lithium Triangle,” an area at the intersection of Argentina, Bolivia, and Chile where the world’s most abundant lithium brine deposits are found.
The methods that are usually used in the brinefield to attempt to measure porosity and permeability, are almost identical to the methods that have been used for many years in the water well industry.
Relative Brine Release Capacity is a test method that involves applying a vacuum to a group of saturated samples. These samples have been taken from the wells at certain depths, and are sent to certified laboratories. The amount of brine produced in response to the vacuum, referred to as the “relative brine release capacity” (RBRC), provides a basis for comparison of the amount of brine produced from different samples. The RBRC is related to the specific yield of a material, which is principally a function of material texture.
Principal problems associated with this method are the time it takes to send the samples to the lab and process the results, as well as the question as to how representative these samples really are of the true in-situ permeability, as a small amount of disturbance always happens during extraction and transport. In-situ methods are preferable in many ways, as the effects of manipulation and transport are removed.
A pumping test involves a well being pumped at a controlled rate and water-level response (drawdown) is measured in one or more surrounding observation wells and optionally in the pumped well (control well) itself; response data from pumping tests are used to estimate the hydraulic properties of aquifers, evaluate well performance and identify aquifer boundaries. “Aquifer performance test” (APT) and “drawdown test” are alternate designations for a pumping test.
A pumping test will give you general well properties, however, it will not give you much information about specific layers in the lithology. This is where packer testing is more useful.
The packer test has been used for many years as a simple method of assessing the hydraulic conductivity of a limited section of a borehole. Packer tests isolate specific sections of soil or bedrock by lowering and inflating the packer in the borehole. Samples can be collected and aquifer tests can be conducted. These tests allow understanding of the vertical distribution of brine quality and hydraulic conductivity. Packer tests consist of measuring the rate of flow and/ or pressure build-up/decay in the test interval over a period of time.
One of the most important aspects of the packer testing, however, is knowing exactly at what depth to carry out the test so as to get the most representative results. This is where new technology comes in to play.
Advanced technology is beginning to make its debut in the Lithium Triangle, in the form of borehole magnetic resonance tools run by Zelandez. The concepts have been taken from the “oilfield” and have been recently adapted and miniaturized for the “brinefield”, bringing an array of hi-tech instruments into the brine sector.
While Borehole Magnetic Resonance has been used routinely in the oil and gas industry for decades, uptake by other industries was hindered by tool size and cost of the logging service. This capability gap has been addressed through the development of an advanced, miniaturised, slim Borehole Magnetic Resonance (BMR) logging tool.
Borehole Magnetic Resonance (BMR) is a unique measurement that responds to both the volumes of fluids present in a rock, and the distribution of those fluids as a function of pore geometry.
In much the same way as Magnetic Resonance Imaging (MRI) is used to interrogate the interior structure of the human body, the BMR tool generates signals that are processed to characterize the pore structure of rocks. The BMR tool is specifically tuned to sense pore network fluids only, enabling precise determination of rock total porosity below the water table and the moisture content in the vadose zone, free fluid content (specific yield), bound fluid content (specific retention) and permeability (hydraulic conductivity). The BMR can also distinguish fluid types, with advanced analysis techniques.
As such, it is a powerful addition to any lithium brine formation characterisation, aimed at evaluating the storage and flow capacity of subsurface formations.
The Insight products developed by Zelandez gives mining companies major advantages, complementing their existing knowledge with state of the art logging tools and processing equipment, followed up with interpretation and analysis for each borehole. Final data is ready to use in record time, allowing our clients to make real operational decisions on filter location and future production and to directly use our data in their workflows.
The BMR gives real time high resolution (8cm) readings which are then sent for processing. Data interpretation is carried out, and the results are combined with other readings that Zelandez carries out in the well such as Spectral Gamma Ray, Dual Laterolog Formation Resistivity, Acoustic Televiewer and Fluid Temperature and Conductivity of borehole fluid. These readings are also combined with lithological columns and other information that the client may have, generating high value data insights.
This information is essential for reservoir calculations and the placement of filters. Target aquifers are easily identified by the outputs, enabling the client to make rapid decisions.
Pioneering brinefield services with the latest technology will assist you in making your project a success.
Shannon Smith
May 2, 2019
Uncategorized
The natural tendency of ferrous material to corrode, is only accelerated in the brinefield, where salinity levels can reach 250 – 280kppm – as salty as it gets. In hyper saline environments, corrosion is a major factor as tools and equipment are devoured at an accelerated pace. Mitigating this loss of material is essential to well integrity, which affects production and sustaining capex of a mine.
The consequences of corrosion in casing are loss in wall thickness and strength, leading to a reduction in ductility, usually leading to casing deformation or total failure.
Un-monitored corrosion can cause unexpected casing failures, resulting in expensive and complicated repair jobs. If left unattended this can lead to aquifer cross contamination and loss of production.
Casing corrosion is often accelerated where there has been damage to the casing during installation, or wear from repeated running of drilling equipment or pumps inside the casing.
The operator must continually monitor and inspect the infrastructure to gauge the integrity of down hole and surface piping equipment. A variety of corrosion monitoring techniques are available. Some corrosion measurement techniques use in line monitoring tools placed directly in the production system. These tools are exposed to the flowing production stream. Other techniques involve laboratory analysis.
The weight loss technique using coupons, a direct visual identification method, is a well-known and simple monitoring method. This technique exposes a specimen of material – the coupon – to the process environment for a given amount of time before a technician removes it from the system and analyses is it for its physical condition and the amount of weight loss. However, the coupon alone cannot be used to accurately pinpoint the time or location of a corrosion event such as a leak.
Apart from this, the coupon technique is useful where easy access is available for placing and extracting the coupon, making it essentially impossible for the well’s down-hole tubular and casing strings.
The remaining options are non-destructive measurement techniques that incorporate one or more of the various logging tools that are deployed down hole on wireline.
Logging techniques for monitoring downhole corrosion include ultrasonic, electromagnetic and mechanical methods that yield detailed information about the location and extent of a corrosion event.
Ultrasonic monitoring employs an ultrasound source to perform measurements and generate images of the downhole environment.
Most ultrasonic tools work by the principle of pulse echo measurement. Measurements include cement evaluation, open hole imaging and corrosion imaging.
An ABI televiewer, transmits an ultrasonic signal at a frequency of 1.2 MHz is designed for cement evaluation and pipe inspection.
The quality of the cement bond is directly related to the degree of casing resonance: a good cement bond dampens the acoustic signal and causes a low amplitude secondary signal to be returned to the transducer; a poor cement job or free pipe allows the casing to ring and returns a higher amplitude echo.
Additionally, the ABI measurements include 2D internal radius imaging of the casing – derived from the wave line of the main echo from the internal surface – and the 2D casing thickness, derived from the frequency response.
The ABI tool records two echoes: the main echo from the internal surface of the casing and the smaller echo from the external surface. The radius and thickness of the casing are computed from the arrival times of the two echoes. The relative sizes, or amplitudes, of the two echoes are qualitative indicators of the casing condition.
Ultrasonic inspection provides several advantages as a corrosion measurement tool, including its sensitivity to both internal and external defence and instantaneous in-field notification when a defect is encountered.
In addition, the technique requires access to only one side of the material to gauge the condition of the entire object and obtain detailed exterior and interior images of the pipe.
However, inspection is difficult for materials that are irregular in profile, such as filters.
Operators may also employ another corrosion monitoring method: electromagnetic (EM)-based inspection. The basic principle of this technique involves measuring the changes to a magnetic field as it passes through a metal object; the changes are related to the condition of the material such as its thickness and its electromagnetic properties.
There exist two types of EM corrosion monitoring tools. The first, a flux leakage tool, magnetizes the metal object using an electromagnet. When the magnetic flux encounters a damaged section of the metal; coils on the tool’s sensors detect this leakage. While this method is useful for measuring abrupt changes in pipe thickness, such as pitting or holes in the inner string, and the location of these changes, it is less effective for monitoring the steady increase of corrosion or corrosion that varies gradually over a large section of pipe or concentric casing configurations.
The second EM-based monitoring technology-the remote field eddy current tool-measures the signal of not only the primary EM field but also the secondary field from the induced eddy currents in the surrounding pipe.
The EM casing inspection tool has been used to detect large holes, casing splits and corrosion-related metal loss from both the internal and the external surfaces of casing.
These measurements can be obtained without the operating company having to pull completion tubing out of the hole, saving rig time, intervention expenses and interruption to production.
An initial reconnaissance run is carried out while the EM casing inspection tool is lowered on wire-line, in order to flag areas of interest for later detailed diagnostic scans to be run when later logging up to the surface. The tool can record a continuous log of both the average inner casing diameter and the total metal thickness, providing corrosion estimates. The tool reads overall metal thickness, enabling detection of corrosion of the outer casing. Radius measurements if the inner casing can be carried out despite the presence of most types of scale.
Identification of horizons with greater corrosion can be identified when the tool is used across several boreholes, allowing for future mitigation measures to be taken at these levels.
In addition to the acoustic and electromagnetic monitoring techniques discussed, mechanical methods are also helpful.
Multifinger mechanical caliper tools rely on direct contact with the pipe wall to measure the deformations arising from the loss of metal due to corrosion or the build-up of scale, however, they do not give any information about the external condition of the pipe wall.
The multifinger caliper tool can be deployed with as many as 60 fingers, depending on internal casing diameters, providing a 3D mechanical image of internal pipe-wall variations.
Repeated measurements can track corrosion over time, allowing Operators to make decisions based on real, and not inferred, data, without the need for removal of the casing until the required time, optimizing down time.
The combination of various tools greatly improves the operator’s understanding of reasons for localized corrosion.
Improved Corrosion Mitigation Through Management
Greater understanding of tubing integrity can be obtained from the use of downhole corrosion monitoring tools allowing the operator to make more-informed and cost-effective mitigation and repair decisions.
As more and more steel pipes are placed in hyper-saline environments, corrosion monitoring will become and increasing problem, and an adequate monitoring system is essential to allow operators to make both profitable and environmentally responsible decisions.
For assistance in monitoring well condition, contact Zelandez, the pioneering brinefield specialists.
Our Insight product PipeSight offers detailed analysis of the well casing condition and completion, using the benefits of the EM, Multi-Finger and Acoustic Televiewer tools.
Shannon Smith
May 3, 2019
Uncategorized
A massive shift toward lithium-ion battery-powered electric vehicles is coming and New Zealand based lithium exploration business Zelandez is playing a major role in helping power these vehicles.
It is high up in the Andes mountains where two-thirds of the world’s lithium resources sit, in a region straddling Argentina, Bolivia and Chile, known as the Lithium Triangle. Here, lithium is extracted from a salty water, known as brine, from vast underground reservoirs found beneath the many salt flats that dot the region.
It is here, Zelandez are using an advanced technology called Borehole Magnetic Resonance (BMR) to scan the rock of ancient underground aquifers in search of a salty water, called brine, which contains the prize, Lithium. The technique is very similar to how medical doctors use MRI images to scan the brain.
This helps provide surety to mining companies on the size of their mineral deposits, lower the costs of brine well testing, while increasing the efficiency of their production wells.
“The lithium brine mining industry is going through a significant growth and learning curve. It’s trying to reduce the time it takes to go from exploration to first production, in order to meet accelerating demand for Lithium, which is expected to increase eightfold over the next 10 years” says Zelandez CEO, Gene Morgan.
“Our clients are delighted with the results from Borehole Magnetic Resonance and we are proud to be helping to bring new technologies to the industry. We speed up exploration and development programs, by offering new ways of doing things with significant cost and time advantages”
The Lithium Ion Battery Market is expected to exceed more than US$ 69 Billion by 2022.
“It’s really exciting to be part of the global story around moving away from fossil fuel power. For example, electric vehicles like Tesla’s, scooters by the likes of Lime, battery power backup for major electricity grids, and many peoples homes are now using lithium batteries.”
Shannon Smith
March 10, 2019
Press
Choose Zelandez for your lithium brine project
