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Experiment Report:

Spectroscopic properties of sand samples in a variety of mediums at high temperature

DISCLAIMER

The results, interpretations and conclusions in this report have been derived from Adrok’s electronic system measurements and, whilst reasonable diligence has been applied to ensure data quality, Adrok cannot guarantee the accuracy or correctness of any results, interpretations and conclusions derived from those measurements. As a consequence, Adrok (nor any of its directors, officers, employees, advisers and consultants, whether past or present) shall be held liable for any loss, costs, damages or expenses of whatever kind (including any consequential loss, costs, damages or expenses) incurred or sustained by any person with respect to such results, interpretations and conclusions or reliance thereon.

ABBREVIATIONS

Adrok = Adrok Ltd Tx = Transmitter Rx = Receiver TCC01 = Adrok typecasting chamber 01.

GLOSSARY OF ADROK’S TERMS

1.0 ABSTRACT SUMMARY

This is a laboratory based study of samples of sand in water and sand in Oil analysed using Adrok’s Atomic Dielectric Resonance (ADR) technology at 200°F (93.3°C) temperature. This study compliments a previous study conducted by Adrok in January 2013 of the same samples at room temperature. (‘Report 00142_v1 Adrok- Chevron.pdf’)

Characterisation of the different sand samples in these different mediums is of vital importance to Chevron to aid the distinction of the different sand zones in a well. Adrok applies their laboratory ADR Spectroscopic techniques to assess the differences in said samples.

2.0 INTRODUCTION

Adrok develops and uses advanced technology to supply geophysical services for locating, identifying and mapping sub-surface natural resources (oil, gas, water and minerals).

Chevron (www.chevron.com) is one of the world's leading integrated energy companies and conducts business worldwide.

Chevron provided Adrok with the following samples and information:

1. Eight (8) samples of sand. In particular, two sand samples in air, two sand samples in oil and two additional samples for sand at slightly different depths. In order to perform the analysis, samples are labelled in the same format as the previous report (‘Report 00142_v1 Adrok-Chevron.pdf’) however, in this instance the term ‘hot’ has been appended to the name to allow comparison with the previous data acquired at room temperature :
2. SAIR, for 1 sand core in air
3. SWATER1 for the 1 sand core in water with 1 horizontal grey line
4. SWATER2 for sand in water with 2 horizontal grey lines
5. SOIL1 for sand in oil with 3 horizontal grey lines and
6. SOIL2 for sand in oil with 4 horizontal grey lines.

The additional samples are labelled as KR89510 and KR89530, respectively. The grey lines refer to tape applied by Chevron, to the external container for each sample. There is no specific instruction as to what these represent but it is assumed these represent the sample number.

In order to clarify the origin of the samples a well log is reported in figure 1.

The differences between the sand samples at high temperature (200°F or 93.3°C), are observed using Adrok’s ADR spectrometer. The variations that occur in the energy signals (primarily E-Range, E-Mean, E-ADR) are related to the physical and chemical properties of each sample. These parameters are used in order to characterise and distinguish the different sand samples.

Figure 1: A sub-section of well log.

2.1 OBJECTIVES

1. ADR analysis of sand samples in order to calculate:
2. ADR ratio (E-ADR)
3. Energy mean (E-mean)
4. Energy range (E-Range)
5. Analyse dataset in order to characterise the sand samples in water and oil, respectively.
6. Distinguish samples based on temperature.

3.0 HYPOTHESES

Using ADR technology, it is possible to highlight the different spectroscopic features between different sand samples in air, water and oil at room temperature and at 93.3°C respectively.

4.0 METHODOLOGY

Each sample was heated up to 200°F (93.33°C) and was scanned in order to obtain the spectral features at high temperature. The ADR analysis of sand samples is performed by acquiring a set of 3 ADR scans for each rock sample. In addition to these scans, an empty chamber is acquired in order to subtract the empty chamber spectra from the rock spectra (i.e. to remove the background). In particular, the processes that are used in order to create these file can be summarised as follows:

1. The ‘compare sample function’ in Radamatic (Adrok’s proprietary software suite) is used to select the best 2 (out of 3) scans for each sample.
2. These two scans are added using Principal Component Addition (PCA).
3. An X3Y3 smoothing filter is applied to the PCA (and empty chamber) image.
4. The image of the empty chamber is then subtracted from the PCA image.

Before the measurements were taken, it was necessary to check the stabilisation of the A01-TCU01 unit. In order to do this, the source of the trace was referenced in the scope screen, by putting the 7th wave in the centre of the scope screen. After referenced, one scan every 20 minutes was acquired. Two parameters were checked, the central position of the 7th wave in the scope and the vertical “jitter” of the source trace.

An alternative way to verify the unit consistency is to record the reference wave in the scope, show the reference wave in the scope and check how the source wave moves, respect to the reference wave. Following stabilisation of the radio frequency source, a set of 3 spectra of the empty chamber were recorded. After these scans, the data for the 7 rock samples was acquired.

Data Analysis

Among the numerous data analysis options that Adrok can employ, one such option is the creation of a false colour image from three separate analytical results. Details on how this is achieved are given in figure 2. The normalisation of analytical data to range from 0 to 1 provides a value that can be used as one of the components of an RGB image (in Matlab). Figure 3 demonstrates the type of image that can be expected. This example looks at sub-surface areas, creating unique colours for layers of fixed thickness, however, the same principles apply when comparing samples within the lab.

In this example, the peach areas enclosed within the solid lines correspond with high responses of the WMF and the E-log. It can be seen that the slight changes in the shade of peach appears to be determined by the small changes in the E-ADR.

5.0 APPARATUS

The chamber setup configuration is presented in figure 4.

Figure 5 shows a rock sample in the chamber and figure 6 presents the receiver trace and the waveform snapshot parameters at the moment of acquisition.

Figure 5. Example of sample position measurement

7.0 RESULTS

Table 1 contains a summary of each sample; name, weight, volume and density acquired at room temperature.

The ADR scans enable the Energy Range (E-Range), Energy Mean (E-Mean) and Energy ADR (E-ADR) to be calculated. These parameters acquired at 93.3°C have been combined to create a false image, as described above and which can be observed in figure 7. Values for ERange, EMean and EADR were normalised (0 to 1) across all samples. These values were then used to create a Red (Erange) / Green (EMean) / Blue (EADR), RGB stripe. This RGB image displays the way in which the three parameters vary relative to one and other (i.e. sample to sample).

In order to have a better comparison between the sand samples in oil and samples in water, figure 8 diplays the RGB values for these samples.

In figure 9 the RGB co-ordinate space value at room temperature, measured previously, is reported.

The ADR harmonic energy variation represents an additional feature related to the physical and chemical composition of the rocks. Figure 10 shows the ADR harmonic energy variation at 93.3°C for the sand samples in water and in oil respectively.