GEOLOGY OF KAROO SHALE GAS AND HOW THIS CAN INFLUENCE

ECONOMIC GAS RECOVERY

DR. DOUG COLE

by

LAYOUT OF PRESENTATION

ONLY THE LOWER ECCA GROUP SHALES ARE SUFFICIENTLY

CARBONACEOUS TO HAVE A GAS-BEARING POTENTIAL

OVER-MATURITY DUE TO DEEP BURIAL AND THE CAPE OROGENY

DESTRUCTION OF GAS POTENTIAL DUE TO DOLERITE INTRUSION

DEPTH RESTRICTION OF 1500 METRES FOR SHALE TARGETS

GEOLOGY OF KAROO GAS-BEARING SHALES AND THEPARAMETERS INFLUENCING ECONOMIC GAS RECOVERY

HYDROCARBON GENERATION THERMAL MATURATION INDICES ANDMATURATION STAGES PLOTTED AGAINST DEPTH OF BURIAL. (From Tissot and Welte, 1984).

DISTRIBUTION OF THE ECCA GROUP AND OTHER STRATIGRAPHIC UNITS IN THE MAIN KAROO BASIN

ASSESSMENT OF SHALE GAS POTENTIAL OF ECCA GROUP FORMATIONS

TOTAL ORGANIC CARBON: 3 TO 12 %

Marcellus Shale 0.3 – 20 % Whitehill Formation 0.5 – 14.7 %Barnett Shale 0.5 – 13 % Prince Albert Formation 0.35 – 12.4 %

Pietermaritzburg Fm 0.3 – 11.6 %Tierberg Formation 0.3 – 5.2 %Volksrust Formation 0.3 – 5.9 %

THICKNESS: > 10 metres

Marcellus Shale 12 – 270 m Whitehill Formation 0.4 – 72 mBarnett Shale 15 – 300 m Prince Albert Formation 30 – 500 m

Pietermaritzburg Fm 0.8 – 420 mTierberg Formation 400 – 1300 mVolksrust Formation 250 – 415 m

DISTRIBUTION OF THE ECCA GROUP AND OTHER STRATIGRAPHIC UNITS IN THE MAIN KAROO BASIN

DISTRIBUTION IN TIME AND SPACE OF PENNSYLVANIAN TO LATEST PERMIANSTRATIGRAPHIC UNITS INCLUDING LITHOLOGY AND ENVIRONMENT IN THE KAROO BASIN

(Chronostratigraphic scale from International Commission on Stratigraphy, 2013)

HYDROCARBON POTENTIAL OF ECCA GROUP SHALES IN THE MAIN KAROO BASIN (From Rowsell and De Swardt, 1976)

DISTRIBUTION OF NATURAL GAS OCCURRENCES IN THE MAIN KAROO BASIN

CR1/68

WHITEHILL FORMATION IN ARID SOUTHWESTERN PART OF THE KAROO BASIN

White weathering due to gypsum, which formed as a result of aerobic bacteria oxidising pyrite to sulphate with the metabolic waste, sulphuric acid, dissolving calcium carbonate followed by the precipitation of gypsum.

OUTCROP NEAR LOERIESFONTEIN

CORE FROM BOSHOF

KL1/78: TIERBERG/WHITEHILL CONTACT AT 67 METRES-DEPTH

WEATHERED WHITEHILL FORMATION SHALE IN CONTACT WITH DOLERITE IN CORE AB1/65 AT 6214.33 FEET-DEPTH

SW1/67: SHALE OF PIETERMARITZBURG FORMATION AT 8005 FEET-DEPTH

DISTRIBUTION AND ISOPACH MAP OF WHITEHILL FORMATION

ISOPACH MAP OF LOWER ECCA GROUP IN MAIN KAROO BASIN

DEPTH TO TOP OF WHITEHILL FORMATION, MAIN KAROO BASIN

DEPTH TO TOP OF LOWER ECCA GROUP IN MAIN KAROO BASIN

DISTRIBUTION OF THERMAL SPRINGS AND ARTESIAN BOREHOLE WATER

DISTRIBUTION OF DOLERITE IN THE KAROO BASIN

Borehole QU1/65

Karoo breccia pipes located on hill. They were probably vents for the escape of methane to the atmosphere during dolerite sill intrusion at 183 Ma (Aarnes et al., 2011).

The pipe contains brecciated host rock, which can be molten and recrystallised in places.

ISOPACH MAP OF DOLERITE WITHIN AND ADJACENT TO WHITEHILL FORMATION

PERCENTAGE DOLERITE WITHIN THE WHITEHILL FORMATION

ISOPACH MAP OF DOLERITE WITHIN THE LOWER ECCA GROUP

PERCENTAGE DOLERITE WITHIN THE LOWER ECCA GROUP

DISTRIBUTION OF STRATIGRAPHIC UNITS IN THE MAIN KAROO BASIN AND POSITION OF VERTICAL SECTIONS

POTENTIAL AREAS FOR SHALE GAS IN THE WHITEHILL FORMATION

POTENTIAL AREAS FOR SHALE GAS IN THE PRINCE ALBERT FORMATION

SPECULATED TECHNICALLY-RECOVERABLE SHALE GAS RESOURCE IN THE WHITEHILL FORMATION

SPECULATED TECHNICALLY-RECOVERABLE SHALE GAS RESOURCE IN THE PRINCE ALBERT FORMATION

APPLICATIONS BY EXPLORATION COMPANIES FOR SHALE GAS IN THE KAROO BASIN

29°S