Best Practices for Shale Core Handling: Transportation, Sampling and Storage for Conduction of Analyses

Abstract

Drill core shale samples are critical for palaeoenvironmental studies and potential hydrocarbon reservoirs. They need to be preserved carefully to maximise their retention of reservoir condition properties. However, they are susceptible to alteration due to cooling and depressurisation during retrieval to the surface, resulting in volume expansion and formation of desiccation and micro fractures. This leads to inconsistent measurements of different critical attributes, such as porosity and permeability. Best practices for core handling start during retrieval while extracting from the barrel, followed by correct procedures for transportation and storage. Appropriate preservation measures should be adopted depending on the objectives of the scientific investigation and core coherency, with respect to consolidation and weathering. It is particularly desirable to maintain a constant temperature of 1 to 4 °C and a consistent relative humidity of >75% to minimise any micro fracturing and internal moisture movement in the core. While core re-sampling, it should be ensured that there is no further core compaction, especially while using a hand corer.

Experimental Investigation of Solid Organic Matter with a 2D NMR T1–T2 Map

“…This could be due to the fact that these shale samples are not fresh, and any free water, if present, has vaporized. This signifies that if fresh samples are not preserved properly, their innate fluid content, such as gas or free water, could disappear. , Thus, considering the current state of the samples, the signals from these specific regions (i.e., regions 3 and 4) were not further analyzed. As a result, this study focused solely on the signals from region 2 (solid OM), which cannot get altered unless samples are exposed to heat.…”

Opportunities in Measuring Multiscale Pore Structure of the Continental Shale of the Yanchang Formation, Ordos Basin, China

“…The shale sample used in this research was collected from the YK01 well. Proper core handling procedures during sampling and storage were performed to reduce physical or chemical alterations [32]. A micro-drilling machine was used for preparing a cylindrical shale sample for micro-CT scanning (Figure 3a).…”

Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

“…They are susceptible to alteration as a result of cooling and depressurization after retrieval to the surface, resulting in volume expansion and generation of desiccation and microfractures. 8 Therefore, outcrop analogs are frequently utilized as an alternative for improving the understanding of the respective reservoir formation. 9−12 The primary purpose of outcrop research is to apply observations and interpretations derived from an inspection of the shale exposures to the equivalent strata of the subsurface.…”

“…However, even though some boreholes are cored and limited cores are recovered, one should consider the damaging effects of drilling mud and its associated chemicals on the retrieved core samples. They are susceptible to alteration as a result of cooling and depressurization after retrieval to the surface, resulting in volume expansion and generation of desiccation and microfractures . Therefore, outcrop analogs are frequently utilized as an alternative for improving the understanding of the respective reservoir formation. − …”