Hydrocarbon Generation in the Taranaki Basin, New Zealand

1984 ◽  
Author(s):  
W.F.H. Pilaar ◽  
L.L. Wakefield
Keyword(s):  
New Zealand ◽  
Hydrocarbon Generation

Diagenetic Control of Porosity and Permeability in Pakawau and Kapuni Group Sandstones, Taranaki Basin, New Zealand

1988 ◽  
Vol 6 (3) ◽  
pp. 263-280 ◽  
Author(s):  
J.D. Collen
Keyword(s):  
New Zealand ◽  
Hydrocarbon Generation ◽  
Burial Diagenesis ◽  
Secondary Porosity ◽  
Calcite Dissolution ◽  
Reservoir Rocks ◽  
Porosity And Permeability ◽  
Reservoir Porosity ◽  
Primary Porosity ◽  
Depth Of Burial

Porosity and permeability of Cretaceous to Oliogocene Pakawau and Kapuni Group sandstones in Taranaki Basin, New Zealand, have been extensively modified by burial diagenesis. Mechanical compaction and the precipitation of silica, carbonate and authigenic clays have caused marked deterioration of potential and actual reservoirs for hydrocarbons. Other authigenic minerals have had less effect. Secondary reservoir porosity and permeability have developed in significant volumes in sandstones at various places, at depths below about 2.5 km. They have formed by dissolution of detrital grains, authigenic cements and authigenic replacement minerals, and by fracturing of rock and grains. The most important process for commercial hydrocarbon accumulation in New Zealand is mesogenetic carbonate (particularly calcite) dissolution. As the most prospective source and reservoir rocks are low in the Cretaceous-Tertiary sequence, the depth of burial necessary for hydrocarbon generation means that most primary porosity has been lost and secondary porosity is essential for a commercial accumulation. Entrapment of hydrocarbons in reservoirs higher in the sequence probably also requires the development of secondary permeability to allow migration.

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