title: Petrogenesis of the Tikorangi Formation fracture reservoir, Waihapa-Ngaere Field, Taranaki Basin

authors: Hood, Steven D.

subjects: Taranaki Basin

abstract: The subsurface mid-Tertiary Tikorangi Formation is the sole limestone and the only fracture-producing hydrocarbon reservoir within Taranaki Basin. This study, based on core material from seven wells in the onshore Waihapa/Ngaere Field, uses a range of petrographic (standard, CL, UV, SEM) and geochemical techniques (stable isotope, trace element data, XRD) to unravel a complex diagenetic history for the Tikorangi Formation. A series of eight major geological-diagenetic events for the host rock and fracture systems have been established, ranging from burial cementation through to hydrocarbon emplacement within mineralized fractures. For each diagenetic event a probable temperature field has been identified which, combined with a geohistory plot, has enabled the timing of events to be determined.
This study has shown that the Tikorangi Formation comprises a complex mixed siliciclastic-carbonate-rich sequence of rocks that exhibit generally tight, pressure-dissolved, and well cemented fabrics with negligible porosity and permeability other than in fractures. Burial cementation of the host rocks occurred at temperatures of 27-37°C from about 0.5-1.0 km burial depths. Partial replacement dolomitisation occurred during late burial diagenesis at temperatures of 36-50°C and at burial depths of about 1.0 km, without any secondary porosity development. Fracturing occurred after dolomitisation and was associated with compression and thrusting on the Taranaki Fault. The location of more carbonate/dolomite-rich units may have implications for the location of better-developed fracture network systems and for hydrocarbon prospectivity and production. Hydrocarbon productivity has been ultimately determined by original depositional facies, diagenesis, and deformation.
Within the fracture systems, a complex suite of vein calcite, dolomite, quartzine, and celestite minerals has been precipitated prior to hydrocarbon emplacement, which have substantially healed and reduced fracture porosities and permeabilities. The occurrence of multiple vein mineral phases, collectively forming a calcite/dolomite-celestite-quartzine mineral assemblage, points to fluid compositions varying both spatially and temporally. The fluids responsible for vein mineralisation in the Tikorangi Formation probably involved waters of diverse origins and compositions. Vein mineralisation records a history of changing pore fluid chemistry and heating during burial, punctuated by changes in the relative input and mixing of downward circulating meteoric and upwelling basinal fluids. A sequence of mineralisation events and their probable burial depth/temperature fields have been defined, ranging from temperatures of 50-80°C and burial depths of 1.0-2.3 km. Hydrocarbon emplacement has occurred over the last 6 m.y. following the vein mineralization events. The Tikorangi Formation must continue to be viewed as a potential fracture reservoir play within Taranaki Basin.

text: Petrogenesis of the Tikorangi Formation fracture reservoir, Waihapa-Ngaere Field, Taranaki Basin The subsurface mid-Tertiary Tikorangi Formation is the sole limestone and the only fracture-producing hydrocarbon reservoir within Taranaki Basin. This study, based on core material from seven wells in the onshore Waihapa/Ngaere Field, uses a range of petrographic (standard, CL, UV, SEM) and geochemical techniques (stable isotope, trace element data, XRD) to unravel a complex diagenetic history for the Tikorangi Formation. A series of eight major geological-diagenetic events for the host rock and fracture systems have been established, ranging from burial cementation through to hydrocarbon emplacement within mineralized fractures. For each diagenetic event a probable temperature field has been identified which, combined with a geohistory plot, has enabled the timing of events to be determined.
This study has shown that the Tikorangi Formation comprises a complex mixed siliciclastic-carbonate-rich sequence of rocks that exhibit generally tight, pressure-dissolved, and well cemented fabrics with negligible porosity and permeability other than in fractures. Burial cementation of the host rocks occurred at temperatures of 27-37°C from about 0.5-1.0 km burial depths. Partial replacement dolomitisation occurred during late burial diagenesis at temperatures of 36-50°C and at burial depths of about 1.0 km, without any secondary porosity development. Fracturing occurred after dolomitisation and was associated with compression and thrusting on the Taranaki Fault. The location of more carbonate/dolomite-rich units may have implications for the location of better-developed fracture network systems and for hydrocarbon prospectivity and production. Hydrocarbon productivity has been ultimately determined by original depositional facies, diagenesis, and deformation.
Within the fracture systems, a complex suite of vein calcite, dolomite, quartzine, and celestite minerals has been precipitated prior to hydrocarbon emplacement, which have substantially healed and reduced fracture porosities and permeabilities. The occurrence of multiple vein mineral phases, collectively forming a calcite/dolomite-celestite-quartzine mineral assemblage, points to fluid compositions varying both spatially and temporally. The fluids responsible for vein mineralisation in the Tikorangi Formation probably involved waters of diverse origins and compositions. Vein mineralisation records a history of changing pore fluid chemistry and heating during burial, punctuated by changes in the relative input and mixing of downward circulating meteoric and upwelling basinal fluids. A sequence of mineralisation events and their probable burial depth/temperature fields have been defined, ranging from temperatures of 50-80°C and burial depths of 1.0-2.3 km. Hydrocarbon emplacement has occurred over the last 6 m.y. following the vein mineralization events. The Tikorangi Formation must continue to be viewed as a potential fracture reservoir play within Taranaki Basin.

year: 2002

title: In vivo utilisation of fructooligosaccharides by sheep faecal bifidobacteria and in vitro antagonistic effects against intestinal pathogens

authors: Li, Yi

abstract: The application of pro-, pre, and synbiotics has been studied primarily in humans and some other monogastric animals. Very few studies have been made to determine their effects on the ruminant intestinal microflora. This project tested whether or not four commercial food-grade oligo- and polysaccharides (three FOS products and one polysaccharide control, Arabinogalactan) could modify the hindgut microflora of sheep towards a more salutary community in which the health-promoting bacterial groups bifidobacteria and lactobacilli predominate, whereas the potential intestinal pathogens and putrefactive bacteria E. coli and sulphite reducing clostridia are suppressed. 
A fructo-6-phosphate phosphokatolase (F6PPK) enzyme-based identification protocol was developed and optimised for identifying and large-scale screening of presumptive bifidobacteria isolates from gut contents or faecal samples. 
An in vivo experiment was then carried out to determine the bifidogenic effect (promotion of bifidobacteria by prebiotics) and the associated antimicrobial effect (suppression of potential pathogens due to the increase in the populations of bifidobacteria) of the four oligo- and polysaccharides on sheep hindgut microflora. Twelve fistulated sheep were managed in a balanced, two Latin square, cross-overdesign experiment, which was run in 5 consecutive periods, with each of 5 treatments (Arabinogalactan, Fibruline, Raftilose, Yacon, and an "acidified saline" carbohydrate-free control) administered to two sheep in each period. Each period consisted of a 1 week of stabilisation to the pelleted diet (no oligo- and polysaccharides), followed by 14 days of daily abomasal supplementation of oligo and polysaccharide/acidified saline, followed by about 12 days of normal pelleted diet. In each period, sheep faecal bifidobacteria, lactobacilli, E. coli/ Enterobacteriaceae, sulphite reducing clostridia, and total anaerobes were enumerated on the day -4 of the "stabilisation" period; days 3 & 9 of the "treatment supplementation" period, and days 15, 16, 19 & 26 after cessation of infusions. Raftilose, Yacon, and Fibruline all exerted significant bifidogenic effects on sheep faecal bifidobacteria after 9 days of daily dosing. Raftilose produced the greatest stimulation of bifidobacteria, reaching counts of approximately 107 CFU/g of faeces. No significant changes in the populations of bifidobacteria were observed in Arabinogalactan-treated sheep. Raftilose and Yacon significantly increased the number of lactobacilli, reaching approximately 107  CFU/g of faeces, after 9 days of daily dosing. With Fibruline, the lactobacilli increase after 9 days of administration was not significant. Arabinogalactan did not elevate the populations of lactobacilli. All four carbohydrate treatments significantly increased the number of total anaerobes to approximately 107 to 108 CFU/g of faeces after 9 days of daily dosing. Supplementation of the test oligo- and polysaccharides had no significant effect on the other determined groups of gut microflora: sulphite reducing clostridia and E. coli/Enterobacteriaceae. There were no significant changes in sheep faecal pH and dry matter content with the four treatments. 
Further in vitro antagonistic experiments were carried out to determine whether or not the isolated sheep faecal bifidobacteria inhibited the growth of potential intestinal pathogens in fermentation broth containing the bifidogenic FOS. One hundred and seventeen bifidobacterial isolates from sheep faeces, were screened for their capacity to utilise different oligo- and polysaccharides. Eighteen of these, with strong fermentation patterns, were selected for further study. In the first preliminary experiment, the 18 isolates plus 2 reference cultures of bifidobacteria were divided into 5 groups of 4 strains each. The 5 groups of bifidobacteria were compared for their in vitro antagonistic activities against E. coli in Peptone Yeast Extract broth containing Yacon, Raftilose, or Fibruline as primary carbon sources. Two groups, exerting 100% antagonistic effects against E. coli after 48-hour anaerobic co-culture at 37°C, were selected for further examination. The eight individual strains in these two groups were tested individually for their antagonistic activities against E. coli in PY broth containing Yacon or Raftilose. Fibruline was eliminated due to its low antagonistic activity by bifidobacteria. Six isolates, showed 100% inhibitory effects against E. coli, which made them particularly promising for use as probiotics. The pH of the fermented broths showed a clear negative correlation with the rank transformed or angular transformed inhibition rate of E. coli. One bifidobacterial strain, P5-Po4-37, was subsequently investigated for its in vitro antagonistic activity against E. coli by determination of bacterial growth kinetics over 60 hours anaerobic incubation at 37°C in PY broth containing Raftilose or Yacon. In this experiment, two different concentrations of bifidobacteria, 107 to 108 CFU/mL and 103 to 104 CFU/mL, were incubated with 104 to 105 CFU/mL of E. coli. After 30 and 48-60 hours of incubation, the growth of E. coli was completely inhibited by both the higher and lower concentrations of bifidobacteria, respectively. The presence of E. coli did not affect the growth of bifidobacteria. With the higher inoculum level, the populations of bifidobacteria increased by only approximately 1.30 log10 cycles; whereas with the lower inoculum level, the populations of bifidobacteria increased by approximately 5.62 log10 cycles, to attain the same maximum viable counts at approximately 109 CFU/mL. Fermentation products were analysed in Raftilose containing PY fermented broth. The inhibitory activity of strain P5-Po4-37 was associated with the production of acetic and lactic acids. Strain P5-Po4-37 also exerted strong antagonistic activities against Clostridium perfringens, Enterobacter aerogenes, Enterococcus faecalis, Klebsiella pneumoniae, Salmonella Dublin, and Salmonella Menston. These findings indicated that Yacon and Raftilose potentiate an organic acid mediated inhibitory action of bifidobacterial strain P5-Po4-37 against the test potential intestinal pathogens. To date, this demonstration of inhibitory activities has been convincingly made only in in vitro studies. The combination of Yacon or Raftilose and bifidobacterial strain P5-Po4-37 may exert a promising synbiotic effect on sheep hindgut microflora, which will be investigated in vivo in the near future.

text: In vivo utilisation of fructooligosaccharides by sheep faecal bifidobacteria and in vitro antagonistic effects against intestinal pathogens The application of pro-, pre, and synbiotics has been studied primarily in humans and some other monogastric animals. Very few studies have been made to determine their effects on the ruminant intestinal microflora. This project tested whether or not four commercial food-grade oligo- and polysaccharides (three FOS products and one polysaccharide control, Arabinogalactan) could modify the hindgut microflora of sheep towards a more salutary community in which the health-promoting bacterial groups bifidobacteria and lactobacilli predominate, whereas the potential intestinal pathogens and putrefactive bacteria E. coli and sulphite reducing clostridia are suppressed. 
A fructo-6-phosphate phosphokatolase (F6PPK) enzyme-based identification protocol was developed and optimised for identifying and large-scale screening of presumptive bifidobacteria isolates from gut contents or faecal samples. 
An in vivo experiment was then carried out to determine the bifidogenic effect (promotion of bifidobacteria by prebiotics) and the associated antimicrobial effect (suppression of potential pathogens due to the increase in the populations of bifidobacteria) of the four oligo- and polysaccharides on sheep hindgut microflora. Twelve fistulated sheep were managed in a balanced, two Latin square, cross-overdesign experiment, which was run in 5 consecutive periods, with each of 5 treatments (Arabinogalactan, Fibruline, Raftilose, Yacon, and an "acidified saline" carbohydrate-free control) administered to two sheep in each period. Each period consisted of a 1 week of stabilisation to the pelleted diet (no oligo- and polysaccharides), followed by 14 days of daily abomasal supplementation of oligo and polysaccharide/acidified saline, followed by about 12 days of normal pelleted diet. In each period, sheep faecal bifidobacteria, lactobacilli, E. coli/ Enterobacteriaceae, sulphite reducing clostridia, and total anaerobes were enumerated on the day -4 of the "stabilisation" period; days 3 & 9 of the "treatment supplementation" period, and days 15, 16, 19 & 26 after cessation of infusions. Raftilose, Yacon, and Fibruline all exerted significant bifidogenic effects on sheep faecal bifidobacteria after 9 days of daily dosing. Raftilose produced the greatest stimulation of bifidobacteria, reaching counts of approximately 107 CFU/g of faeces. No significant changes in the populations of bifidobacteria were observed in Arabinogalactan-treated sheep. Raftilose and Yacon significantly increased the number of lactobacilli, reaching approximately 107  CFU/g of faeces, after 9 days of daily dosing. With Fibruline, the lactobacilli increase after 9 days of administration was not significant. Arabinogalactan did not elevate the populations of lactobacilli. All four carbohydrate treatments significantly increased the number of total anaerobes to approximately 107 to 108 CFU/g of faeces after 9 days of daily dosing. Supplementation of the test oligo- and polysaccharides had no significant effect on the other determined groups of gut microflora: sulphite reducing clostridia and E. coli/Enterobacteriaceae. There were no significant changes in sheep faecal pH and dry matter content with the four treatments. 
Further in vitro antagonistic experiments were carried out to determine whether or not the isolated sheep faecal bifidobacteria inhibited the growth of potential intestinal pathogens in fermentation broth containing the bifidogenic FOS. One hundred and seventeen bifidobacterial isolates from sheep faeces, were screened for their capacity to utilise different oligo- and polysaccharides. Eighteen of these, with strong fermentation patterns, were selected for further study. In the first preliminary experiment, the 18 isolates plus 2 reference cultures of bifidobacteria were divided into 5 groups of 4 strains each. The 5 groups of bifidobacteria were compared for their in vitro antagonistic activities against E. coli in Peptone Yeast Extract broth containing Yacon, Raftilose, or Fibruline as primary carbon sources. Two groups, exerting 100% antagonistic effects against E. coli after 48-hour anaerobic co-culture at 37°C, were selected for further examination. The eight individual strains in these two groups were tested individually for their antagonistic activities against E. coli in PY broth containing Yacon or Raftilose. Fibruline was eliminated due to its low antagonistic activity by bifidobacteria. Six isolates, showed 100% inhibitory effects against E. coli, which made them particularly promising for use as probiotics. The pH of the fermented broths showed a clear negative correlation with the rank transformed or angular transformed inhibition rate of E. coli. One bifidobacterial strain, P5-Po4-37, was subsequently investigated for its in vitro antagonistic activity against E. coli by determination of bacterial growth kinetics over 60 hours anaerobic incubation at 37°C in PY broth containing Raftilose or Yacon. In this experiment, two different concentrations of bifidobacteria, 107 to 108 CFU/mL and 103 to 104 CFU/mL, were incubated with 104 to 105 CFU/mL of E. coli. After 30 and 48-60 hours of incubation, the growth of E. coli was completely inhibited by both the higher and lower concentrations of bifidobacteria, respectively. The presence of E. coli did not affect the growth of bifidobacteria. With the higher inoculum level, the populations of bifidobacteria increased by only approximately 1.30 log10 cycles; whereas with the lower inoculum level, the populations of bifidobacteria increased by approximately 5.62 log10 cycles, to attain the same maximum viable counts at approximately 109 CFU/mL. Fermentation products were analysed in Raftilose containing PY fermented broth. The inhibitory activity of strain P5-Po4-37 was associated with the production of acetic and lactic acids. Strain P5-Po4-37 also exerted strong antagonistic activities against Clostridium perfringens, Enterobacter aerogenes, Enterococcus faecalis, Klebsiella pneumoniae, Salmonella Dublin, and Salmonella Menston. These findings indicated that Yacon and Raftilose potentiate an organic acid mediated inhibitory action of bifidobacterial strain P5-Po4-37 against the test potential intestinal pathogens. To date, this demonstration of inhibitory activities has been convincingly made only in in vitro studies. The combination of Yacon or Raftilose and bifidobacterial strain P5-Po4-37 may exert a promising synbiotic effect on sheep hindgut microflora, which will be investigated in vivo in the near future.

year: 2003

title: Studies on the conservation of waterlogged wood in New Zealand

authors: Wallace, Roderick Thomas

abstract: This thesis is a study of properties of certain New Zealand woods recovered from waterlogged environments. The woods are those which were commonly used by the pre-european Maori to make artefacts, and the properties are those which affect the way these artefacts can be conserved after they have been removed from wet archaeological sites.
The properties studied were (a) the species of wood used (b) the forms and shapes of the timbers (c) the densities (d) directional shrinkages, and (e) directional penetrabilities of each wood. The results of this research are intended to aid conservators to correctly treat the artefacts. 
The research began with studies of (a) New Zealand wet site archaeology, (b) the structure and properties of wood in general, and (c) the techniques used to conserve waterlogged wood worldwide.
This was followed by a survey of circa. 1000 wooden Maori artefacts from Museums involving the identification, by thin section microscopy, of wood species. 30 wood types from 22 tree species were found to have been widely used. A collection was made of samples of each type in different states of decay. 
Each sample was tested for density, directional shrinkage and directional penetrability.
The penetrability was measured by vacuum impregnation of water into wood blocks. Results were compared to those from sound oak (Quercus robur), a wood which has been studied intensively by conservators in Europe. 
Detailed summaries of the conservation properties of 26 wood types are given. This reveals that while some New Zealand woods are easy to conserve others provide considerable problems. The latter woods are all highly durable in wet sites, extremely dense, have high shrinkages and are highly impenetrable. These will require special types of treatment to avoid damage during conservation.

text: Studies on the conservation of waterlogged wood in New Zealand This thesis is a study of properties of certain New Zealand woods recovered from waterlogged environments. The woods are those which were commonly used by the pre-european Maori to make artefacts, and the properties are those which affect the way these artefacts can be conserved after they have been removed from wet archaeological sites.
The properties studied were (a) the species of wood used (b) the forms and shapes of the timbers (c) the densities (d) directional shrinkages, and (e) directional penetrabilities of each wood. The results of this research are intended to aid conservators to correctly treat the artefacts. 
The research began with studies of (a) New Zealand wet site archaeology, (b) the structure and properties of wood in general, and (c) the techniques used to conserve waterlogged wood worldwide.
This was followed by a survey of circa. 1000 wooden Maori artefacts from Museums involving the identification, by thin section microscopy, of wood species. 30 wood types from 22 tree species were found to have been widely used. A collection was made of samples of each type in different states of decay. 
Each sample was tested for density, directional shrinkage and directional penetrability.
The penetrability was measured by vacuum impregnation of water into wood blocks. Results were compared to those from sound oak (Quercus robur), a wood which has been studied intensively by conservators in Europe. 
Detailed summaries of the conservation properties of 26 wood types are given. This reveals that while some New Zealand woods are easy to conserve others provide considerable problems. The latter woods are all highly durable in wet sites, extremely dense, have high shrinkages and are highly impenetrable. These will require special types of treatment to avoid damage during conservation.

year: 1985