OR/17/037 Introduction

Hannis, S, and Gent, C. 2017. Petrophysical interpretation of selected wells near Liverpool for the UK Geoenergy Observatories project. British Geological Survey Internal Report, OR/17/037.

This report describes the methodology and results of a ‘quick-look’ deterministic petrophysical study of lithology and reservoir quality for two wells near Liverpool (Figure 1). Geophysical logging curve responses were used to interpret output curves and formation averages using Interactive Petrophysics software under academic license (IPTM, Version 4.2.2015.61, LR- Senergy).

Figure 1    Location of wells deeper than 1 km in the vicinity of the study area (pink circle). The two wells interpreted in this report are inside the pink circle.

Data available for each well in this study is summarised in Table 1. Data types and sources of data are discussed in more detail in the Data types and sources section. How the data was prepared is outlined in Data preparation and the interpretation methods are described in Data types and sources section. How the data was prepared is outlined in Petrophysical interpretation of lithology and porosity. In addition, each well is described in its own appendix, and these include well sketches, and summary log plots of data available and petrophysical results etc, together with any explanations of well-specific details that differ from the general method provided in Method.

Petrophysical results are provided in Results. The following curves have been interpreted for each well for this project based on geophysical log responses: Volume of clay (V_CL); Identification of intervals of specific non-reservoir lithologies, in this case coals (V_COAL); Porosity (PHIE & PHIT). For the Westphalian A and deeper strata in Ince Marshes 1, Total Organic Carbon (TOC) content has also been calculated. These are curves are provided separate to this report, both digitally as *.LAS files and as PDF log summary plots at 1:500 scale. More details can be found in Interpreted curves.

From these curves and the wellbore stratigraphy (Appendix 3 - Stratigraphic interpretations), reservoir properties were output by formation: Gross thickness; Net, Net to Gross and Average porosity and porosity range (across the net intervals) (Summary of reservoir petrophysical results, Table 6). The derivation of these outputs are described in Calculation of thicknesses, average values and ranges.

Summary of parameters and quality of the output interpreted curves documents parameters used and gives a summary of the output data quality (Table 9). This, together with knowledge of the methods used to derive the outputs explained elsewhere in the report, should enable the reader to get an idea of the confidence that should be placed in the output results.

The reservoir quality and potential permeability is discussed in Discussion. The potential of the shale intervals as unconventional reservoir or source rock is discussed in Total Organic Carbon (TOC) calculation results.

Table 1    Summary of data available for the wells studied

Well	Wireline logging services	Input curves	Total logged interval (m)	Total length of core cut (m)	Sidewall cores recovered	# of samples for each analysis			TVD survey & max. deviation (°)	Further details…
						XRD	TOC	XRF		…in Tables 2, 3, 4 and 7 and…
Kemira 1 (SJ47NE/101)	GR, density, neutron, sonic over most, resistivity middle section only.	9	1405.7	0	0	0	0	0	N, 6	Appendix 1
Ince Marshes 1 (SJ47NE/100)	Standard quad-combo, DSI, FMI, ECS	45+	1085.7	198.7	98	47	82	8	Y, 9	Appendix 2