Accelerating the Pace of Discovery
Overview
Raphael employs its MaxEx Direct regional exploration process to find, confirm and quantify hydrocarbon indications by hydrocarbon phase and depth to build a deep portfolio of leads and prospects. The MaxEx Direct process uses four classes of geophysical methods:
Regional radiometric reconnaissance surveys - proprietary processing of regional survey data that produces microseepage induced gamma anomaly indirect hydrocarbon indication (IHI) leads;
3D GravMag structure mapping - proprietary analysis of gravity and magnetic data that delineates the 3D model of a geologic structure;
Electromagnetic analogue induction (EMAI) logging and modeling - a magnetotelluric method that provides the equivalent of high-resolution induction logs - reservoir sections as thin as 2 to 3 meters (6 to 10 feet) - with fluid indications - oil, gas, water - and inferred porosity and permeability with the EMAI logs used to build a model by hydrocarbon phase of the reservoir at depth; and
Near-surface microseepage studies - studies of microseepages in the near-surface that migrate near vertically from a pressured hydrocarbon system.
The outcome of the MaxEx Direct exploration process is a structurally conformed 3D EMAI reservoir model, further validated with correlation to microseepage intensity attributes, completed in significantly less time, cost and exploration footprint than a comparable 3D seismic structure with a DHI (direct hydrocarbon indication).
Features of MaxEx Direct Exploration Process
The MaxEx Direct exploration process offers several features that markedly improve exploration efficiency:
Dual-sourced hydrocarbon indication - 3D EMAI reservoir models correlate two different indication sources - near-surface microseepage intensity attributes and EMAI logging of reservoir indications at depth - for a hydrocarbon indication that provides a high confidence all geologic chance factors - source, migration, seal, reservoir, trap - are working to form a petroleum system.
Integration of multiple microseepage indication methods - the MaxEx Direct process begins and ends with microseepage indication methods - regional reconnaissance surveys seeking microseepage induced radiometric gamma anomaly IHI leads and correlation of microseepage intensity attributes to 3D EMAI reservoir models.
Notably, a compilation of published results of various microseepage indication methods found that 80 percent of wells (1,374 of 1,718) drilled with a positive microseepage indication were completed while only 14% of wells (223 of 1,590) drilled without a positive microseepage indication were completed (Schumacher AAPG 2017). With the MaxEx Direct hydrocarbon indication process incorporating multiple microseepage indication methods, a structurally conformed 3D EMAI prospect is expected to enjoy a high chance of exploration success.
Reservoir sweet spots - as reviewed below, a 2020 Raphael radiometric survey of much of the South Australia area of the Cooper Eromanga basins mapped high intensity radiometric “sweet spots” that included wells producing 88% of study production. With higher density EMAI logging and microseepage locations than radiometric reconnaissance surveys, 3D EMAI reservoir models can likely map better “sweet spots” that improve well placement to increase exploration efficiency.
Accelerates the pace of discovery - with radiometric and gravity and magnetic data normally collected with fixed-wing surveys while EMAI logging and near-surface microseepage field studies are focused on the area of 3D GravMag structures with one or more IHIs, only small crews and abbreviate field times are needed, enabling MaxEx Direct 3D EMAI reservoir model prospects to be generated with far less time, capital and footprint than a comparable 3D seismic campaign.
Add drilling campaigns testing structurally conformed 3D EMAI reservoir model prospects correlated to microseepage intensity attributes and quantified by hydrocarbon phase and depth and the MaxEx Direct process markedly accelerates the pace of discovery as well as saves vast amounts of capital and footprint.
Geophysical Methods Employed by MaxEx Direct Exploration Process
Radiometrics
The initial phase of the MaxEx Direct hydrocarbon indication process is regional radiometric reconnaissance surveys seeking microseepage induced radiometric gamma anomaly IHI leads.
Raphael uses the ARAD radiometric method, a refinement of the traditional DRAD radiometric technique, that leverages big data analysis to extract more reliable IHI leads.
Two case studies have demonstrated the efficacy of the ARAD method to target and map high pressured hydrocarbon accumulations.
Perth Basin
A 2018 study of the Dongara area of the Perth Basin totaling ~ 5,000 km2 (1.2 million acres) targeted and mapped the recent Waitsia discovery as well as the pre-drill targeting of the Strike Energy Limited West Erregulla 1.5 TCF gas discovery (2C and prospective resource).
In addition, the study area included several heavily depleted fields that were not targeted by the ARAD survey, a demonstration that radiometric gamma anomalies are a contemporaneous indication of a pressured petroleum system.
Cooper-Eromanga Basins
A 2020 study of the South Australia area of the Cooper-Eromanga basins totaling ~ 40,000 km2 (9.9 million acres) that, with the benefit of extensive well information and additional algorithms, mapped high intensity ARAD radiometric “sweet spots” that included wells producing 88% of study production (1.13 BnOEB / 1.29 BnOEB) as well as reduced an already nominal number of dry holes by 91%.
3D GravMag
Raphael developed the 3D GravMag processing that maps subsurface structures at depth.
The 3D GravMag method extracts points from gravity and magnetic data and using multiple algorithms and big data analysis methods, delivers the equivalent of 3D seismic subsurface mapping with a resolution on the Z-Axis as low as 50 meters.
3D GravMag mapping has produced results comparable to 2D and 3D seismic mapping of structures in the Browse (Poseidon field), Perth and Cooper-Eromanga Basins.
Near Surface Geochemical
Scientists have used surface geochemical techniques since 1930 to explore for hydrocarbons. These techniques look for the effects of minute levels of hydrocarbons that leak through imperfect seals and migrate as macroseepage via faults or as microseepage vertically through reservoir overburden (Klusman, 1993; Coleman et. al. 1997; Anderson, 2006).
As noted above, published results of various microseepage indication methods found that 80 percent of wells (1,369 of 1,718) drilled with a positive microseepage indication were completed, quantifying the significance of incorporating multiple microseepage methods into the MaxEx Direct exploration process.
EMAI Logging
Electromagnetic analogue induction (EMAI) logging is a magnetotelluric technique that uses the naturally occurring electromagnetic signal to log reservoir indications of fluids - oil, gas, water - and inferred porosity and permeability. The method can log reservoir indications as thin as 3 meters (10 feet) down to a depth of ~6,000 meters (19,700 feet) .
The EMAI logging locations can be a few as one or two locations for a quick test of the prospectivity of a lead as well as a grid survey to define the oil-water contact of a reservoir.
Structurally Conformed EMAI Reservoir Model Correlated to Microseepage Intensity Attributes
The combination of 3D GravMag and EMAI techniques delivers the equivalent of seismic subsurface mapping with direct hydrocarbon indication attributes. In addition, a 3D EMAI reservoir model is further validated with correlation of microseepage intensity attributes, and in some instances, by hydrocarbon phase, to the thickness and inferred porosity of a 3D EMAI reservoir model, and if deemed necessary, a limited number of 2D seismic lines.