scholarly journals Hydrocarbon prospectivity of the miocene-pliocene clastic reservoirs, Northern Taranaki basin, New Zealand: integration of petrographic and geophysical studies

2022 ◽  
Author(s):  
Ahmed A. Radwan ◽  
Bassem S. Nabawy
Keyword(s):  
New Zealand ◽  
Gamma Ray ◽  
Well Log ◽  
Thin Sections ◽  
Early Pliocene ◽  
Fine Grained ◽  
The North ◽  
High K ◽  
Clastic Reservoirs ◽  
Self Potential

AbstractIn this study, it is aimed to characterize the Early pliocene sandstone (EP-SD) and the Late Miocene-Early Pliocene Mangaa sandstone reservoirs and the efficiency of their sealing cap rocks using the petrographical and petrophysical data of these sandstone zones in northern Taranaki basin, New Zealand. The prospective potential reservoirs were studied using impregnated thin sections, XRD data analysis, and well log data (self-potential, gamma-ray, sonic, density, neutron, shallow\deep resistivity and PEF) to characterize the reservoir zones, in addition to Mercury intrusion capillary pressure data (MICP) to check the efficiency of some potential seals. The EP-SD and the Mangaa sandstone units are typically poorly consolidated very fine sandstone to siltstone, with porosities averaging 25%. The sands are composed of quartz (38.3–57.4%), with common feldspars (9.9–15.2% plagioclase, and 2.7–6.3% K-feldspars) and up to 31.8% mica. In Albacore-1 well to the north of the Taranaki Basin, the Mangaa formation includes three separate for each of the EP-SD zones (EP-SD1, EP-SD2, and EP-SD3), and the Mangaa sequence (Mangaa-0, Mangaa-1, and Mangaa-2). The thin section studies indicate that, the studied samples are grouped into greywackes, arenites and siltstone microfacies with much lithic fragments and feldspars, sometimes with glauconite pellets. From the XRD data, it is achieved that the mineral composition is dominated by quartz, mica/illite, feldspars, and chlorite. The petrophysical investigation revealed absence of pay zones in the EP-SD zones, and presence of thin pay zone with net thickness 5.79 m and hydrocarbon saturation of about 25.6%. The effective porosities vary between 23.6 and 27.7%, while the shale volume lies between 12.3 and 16.9%. Although the shale content is relatively low, the relatively high API (50–112 API of average 75 API) is contributed by the relatively high K-feldspar content and intercalations with thin siltstone and muddy siltstone beds. Sealing units include the intra-formational seals within the Mangaa sequence, mudstones and fine grained units overlying the Mangaa and further intra-formational mudstones, within the shallower EP-SD units. The efficiency of these seals indicates the capability to trap 16.4–40.6 m gas or 17.4–43.0 m oil which is relatively low in correlation with their efficiency in the central parts of the Taranaki Basin Overlying the primary seals, mudstones of the Giant Foresets Formation provide additional regional seal.

scholarly journals Paleomagnetic Studies of the Late Miocene Mangapoike River Section, Northern Hawke's Bay, New Zealand

2021 ◽  
Author(s):  
◽  
Ian Craig Wright
Keyword(s):  
New Zealand ◽  
Late Miocene ◽  
Rotation Rate ◽  
Time Lag ◽  
Marked Change ◽  
Strain Analysis ◽  
River Section ◽  
Early Pliocene ◽  
The North ◽  
Regional Tectonic

<p>The Mangapoike River section (38.9 degrees S, 177.6 degrees E), on the eastern limb of the Wairoa Syncline, northern Hawke's Bay, is a thick (> 4000 m) and well exposed sequence of Waiauan to Waipipian sediments in which foraminiferal and radiolarian biostratigraphy and silicic tuff lithostratigraphy are well known. An Early Pliocene magnetostratigraphy has been determined by Kennett and Watkins (1974). The present study extends the magnetostratigraphy to the Middle -Late Miocene, and establishes a late Miocene to Early Pliocene 3000 m magnetostratigraphic reference column for New Zealand. The only identifiable remanence carrying magnetic mineral in the Mangapoike sediments is titanomagnetite. Its chemistry does not vary with grain size. Oxidation of the titanomagnetite is deuteric, and thus pre-depositional. Fluctuations of titanomagnetite concentration between 10-3 to 10-4 wt percent are the main influence on the variation of NRM intensity. Viscous magnetisations characterised by both the alignment of NRM directions in a general present day field direction and remanence decay and aquisition over laboratory time were recognised in 85 percent of the 1204 paleomagnetic specimens. Secondary magnetisations were removed by thermal demagnetisation at temperatures varying between 200 degrees C and 320 degrees C. AF demagnetisation was not effective in removing viscous magnetisations, even at peak alternating fields of 35 mT, since the coercivities of the primary and secondary magnetisations overlap completely. The random relationship between the degree of bioturbation and in-site dispersion at individual sites indicates the magnetisation is acquired after bioturbation, and thus is a post-depositional detrital magnetisation. The time lag between deposition and acquisition of the magnetisation is approximately 1000 yrs. Six normal (MN1 - MN6) and seven reversed (MR1 - MR7) polarity magnetozones are identified within the late Miocene at Mangapoike. Only one normal magnetozone (MN6) is recognised in the stratigraphic interval equivalent to that from which Kennett and Watkins (1974) reported two normal zones (C1 and C2). MN6 is correlated to C2. C1 is inferred to be an uncleaned normal overprint. The magnetozones are correlated to Chrons 11 to 4, which implies an average sedimentation rate of 64 cm/1000 yrs. The previously known Miocene - Pliocene 3 degrees angular unconformity at Mangapoike (Hornibrook 1977) represents the period from 6.3 Ma to at least 5.41 Ma. A previously unrecognised unconformity from at least 6.86 to at least 6.42 Ma is postulated, based on the preferred magnetostratigraphic interpretation. The presence of the unconformity is supported by radiolarian and benthic foraminiferal biostratigraphy. Three distinct lithological events at Mangapoike, based both on the synchroneity with deep-sea benthic delta 18O records and unconformities of the Vail-curve, are inferred to result from glacioeustatism. At Mangapoike, the Waiauan - Tongaporutuan boundary, as defined by the incoming of Bolivinita cf pohana, has a magnetostratigraphic age of 10.3 Ma. Both the LAD of Loxostomum truncatum and the FAD of Bolivinita cf pohana are less than 42,000 yrs. younger than the late Waiauan glacioeustatic event. The Waiauan - Tongaporutuan boundary is thus postulated to result from glacioeustatism. Glacioeustatism may also explain the excellent age correlation between the base of the Tongaporutuan and the base of the Tortonian stratotype. Correlation of the late Miocene and early Pliocene magnetostratigraphies and biostratigraphies of on-shore New Zealand with either of the magnetostratigraphic interpretations of DSDP Site 594 results in an unacceptably high diachroneity of some planktic taxa of 1.8 Ma over 3.6 degrees of latitude. Of four possiblities to resolve the anomaly, incorrect magnetostratigraphic correlations at Site 594 is the most likely. The previously determined age of 6.2 Ma for the LAD of Globoquadrina dehiscens in New Zealand is erroneous. A magnetostratigraphic age for the LAD of G. dehiscens at Mangapoike is 9.2 Ma. This age is not an extinction date for the taxon throughout New Zealand, and the LAD may well be erratic and diachronous within New Zealand. The Wairoa Syncline, a forearc basin within the Hikurangi margin, has a rotation rate as determined from declination directions, of 7-8 degrees /Ma for the last 5 Ma. Of this less than 1.5 degrees /Ma is due to apparent polar wander of the Australian plate. Extrapolation of this rate towards the present is consistent with a present day rotation rate of 7 degrees /Ma derived from strain analysis of geodetic data. Prior to 10 Ma the rate of tectonic rotation is poorly constrained and may vary between 3 degrees /Ma and 0 degrees /Ma. The change in the rate of rotation of the Wairoa Syncline around 5 Ma is probably related to a marked change in regional tectonic regime involving opening and spreading to the north of New Zealand and compression and shortening to the south.</p>

scholarly journals Influence of the Gamma Ray towards Porosity Evaluation of the Rocks Using Well Log Measurement

2015 ◽  
Vol 15 (2) ◽  
pp. 103
Author(s):  
Puguh Hiskiawan
Keyword(s):  
Physical Parameter ◽  
Gamma Ray ◽  
The Self ◽  
Physical Parameters ◽  
Well Log ◽  
Earth Surface ◽  
Rock Density ◽  
Potential Value ◽  
Rock Structure ◽  
Self Potential

Well Log method is one of the geophysics methods used to examine rock structure under earth surface. This research is studied by using utilizing influence of the gamma ray to physical parameter on well log measurement. This research is explained to compare the measuring data with some physical parameters. The results shown that the rock density was about 2.00 – 2.50 g/cc, the rock porosity was round 2.00 – 2.50 g/cc, whereas the resistivity has 2 Ωm to 60 Ωm. All those vaiables were measured at same depth 3420 – 3470 ft. Furthermore, the self potential value was the highest negatively. The result from physical parameter provided meaning about anomaly positively of hydrocarbon existing.Keywords: Well Log, gamma ray, hydrocarbon  

Geomechanics Without Sonic In Tight Gas Reservoirs In The North Of Oman

2015 ◽  
Author(s):  
Rinat Lukmanov ◽  
Mohammed Aamri
Keyword(s):  
Hydraulic Fracturing ◽  
Gamma Ray ◽  
Total Porosity ◽  
Horizontal Stress ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
The North ◽  
Minimum Horizontal Stress ◽  
Stress Contrast ◽  
Clastic Reservoirs

Abstract Barik and Miqrat are the main two deep tight gas clastic reservoirs in several fields of Oman. In the area of the current Study, these reservoirs are encountered at depth 4500-5200 m and contain rich gas/condensate. Average permeability for different units ranges from 0.02 to 4 mD, porosity up to 14% with averages values within the range 5-10%. In order to produce economically, hydraulic fracturing is applied in these reservoirs. Geomechanics calculations are essential for the fracturing design. One of the particular challenges is fracture containment within the gas zone because in view of low stress contrast between different lithologies. Sonic data are normally used for these calculations. However, based on the analysis of the Sonic data available, a simple workflow was developed for Geomechanics calculations which don't require Sonic. A good restoration of compressional Sonic was achieved using the total porosity and the rock volumetrics as the input data. The analysis reveals good correlation between the complex rock constituents and the Poisson's ratio. These findings resulted in good Shear Sonic restoration and fir for purpose calculations of Geomechanics parameters. The Minimum horizontal stress data obtained based on actual Sonic data matches very well with the Minimum horizontal stress derived without Sonic resulting in practically the same hydraulic fracturing design. The normalization of Gamma Ray and Neutron and rigorous multimineral analysis was a key to success for this methodology. A fit for purpose methodology was developed which enabled to perform identification of 3 key rock constituents even from the basic Triple Combo. The methodology for Geomechanics without Sonic was used for frac design in several wells. The proposed model is found to be very robust.

scholarly journals Paleomagnetic Studies of the Late Miocene Mangapoike River Section, Northern Hawke's Bay, New Zealand

2021 ◽  
Author(s):  
◽  
Ian Craig Wright
Keyword(s):  
New Zealand ◽  
Late Miocene ◽  
Rotation Rate ◽  
Time Lag ◽  
Marked Change ◽  
Strain Analysis ◽  
River Section ◽  
Early Pliocene ◽  
The North ◽  
Regional Tectonic

<p>The Mangapoike River section (38.9 degrees S, 177.6 degrees E), on the eastern limb of the Wairoa Syncline, northern Hawke's Bay, is a thick (> 4000 m) and well exposed sequence of Waiauan to Waipipian sediments in which foraminiferal and radiolarian biostratigraphy and silicic tuff lithostratigraphy are well known. An Early Pliocene magnetostratigraphy has been determined by Kennett and Watkins (1974). The present study extends the magnetostratigraphy to the Middle -Late Miocene, and establishes a late Miocene to Early Pliocene 3000 m magnetostratigraphic reference column for New Zealand. The only identifiable remanence carrying magnetic mineral in the Mangapoike sediments is titanomagnetite. Its chemistry does not vary with grain size. Oxidation of the titanomagnetite is deuteric, and thus pre-depositional. Fluctuations of titanomagnetite concentration between 10-3 to 10-4 wt percent are the main influence on the variation of NRM intensity. Viscous magnetisations characterised by both the alignment of NRM directions in a general present day field direction and remanence decay and aquisition over laboratory time were recognised in 85 percent of the 1204 paleomagnetic specimens. Secondary magnetisations were removed by thermal demagnetisation at temperatures varying between 200 degrees C and 320 degrees C. AF demagnetisation was not effective in removing viscous magnetisations, even at peak alternating fields of 35 mT, since the coercivities of the primary and secondary magnetisations overlap completely. The random relationship between the degree of bioturbation and in-site dispersion at individual sites indicates the magnetisation is acquired after bioturbation, and thus is a post-depositional detrital magnetisation. The time lag between deposition and acquisition of the magnetisation is approximately 1000 yrs. Six normal (MN1 - MN6) and seven reversed (MR1 - MR7) polarity magnetozones are identified within the late Miocene at Mangapoike. Only one normal magnetozone (MN6) is recognised in the stratigraphic interval equivalent to that from which Kennett and Watkins (1974) reported two normal zones (C1 and C2). MN6 is correlated to C2. C1 is inferred to be an uncleaned normal overprint. The magnetozones are correlated to Chrons 11 to 4, which implies an average sedimentation rate of 64 cm/1000 yrs. The previously known Miocene - Pliocene 3 degrees angular unconformity at Mangapoike (Hornibrook 1977) represents the period from 6.3 Ma to at least 5.41 Ma. A previously unrecognised unconformity from at least 6.86 to at least 6.42 Ma is postulated, based on the preferred magnetostratigraphic interpretation. The presence of the unconformity is supported by radiolarian and benthic foraminiferal biostratigraphy. Three distinct lithological events at Mangapoike, based both on the synchroneity with deep-sea benthic delta 18O records and unconformities of the Vail-curve, are inferred to result from glacioeustatism. At Mangapoike, the Waiauan - Tongaporutuan boundary, as defined by the incoming of Bolivinita cf pohana, has a magnetostratigraphic age of 10.3 Ma. Both the LAD of Loxostomum truncatum and the FAD of Bolivinita cf pohana are less than 42,000 yrs. younger than the late Waiauan glacioeustatic event. The Waiauan - Tongaporutuan boundary is thus postulated to result from glacioeustatism. Glacioeustatism may also explain the excellent age correlation between the base of the Tongaporutuan and the base of the Tortonian stratotype. Correlation of the late Miocene and early Pliocene magnetostratigraphies and biostratigraphies of on-shore New Zealand with either of the magnetostratigraphic interpretations of DSDP Site 594 results in an unacceptably high diachroneity of some planktic taxa of 1.8 Ma over 3.6 degrees of latitude. Of four possiblities to resolve the anomaly, incorrect magnetostratigraphic correlations at Site 594 is the most likely. The previously determined age of 6.2 Ma for the LAD of Globoquadrina dehiscens in New Zealand is erroneous. A magnetostratigraphic age for the LAD of G. dehiscens at Mangapoike is 9.2 Ma. This age is not an extinction date for the taxon throughout New Zealand, and the LAD may well be erratic and diachronous within New Zealand. The Wairoa Syncline, a forearc basin within the Hikurangi margin, has a rotation rate as determined from declination directions, of 7-8 degrees /Ma for the last 5 Ma. Of this less than 1.5 degrees /Ma is due to apparent polar wander of the Australian plate. Extrapolation of this rate towards the present is consistent with a present day rotation rate of 7 degrees /Ma derived from strain analysis of geodetic data. Prior to 10 Ma the rate of tectonic rotation is poorly constrained and may vary between 3 degrees /Ma and 0 degrees /Ma. The change in the rate of rotation of the Wairoa Syncline around 5 Ma is probably related to a marked change in regional tectonic regime involving opening and spreading to the north of New Zealand and compression and shortening to the south.</p>

Studies of Ptiliidae (Coleoptera) in the Spirit Collection of the Natural History Museum, London 2: New species and records from P. Hammond's visit to New Zealand in 1983–84

2018 ◽  
Vol 154 (3) ◽  
pp. 179-196
Author(s):  
Michael Darby
Keyword(s):  
New Species ◽  
New Zealand ◽  
Natural History ◽  
Natural History Museum ◽  
History Museum ◽  
The North ◽  
Three New Species ◽  
North And South

Some 2,000 Ptiliidae collected in the North and South Islands of New Zealand in 1983/1984 by Peter Hammond of the Natural History Museum, London, are determined to 34 species, four of which are new to the country. As there are very few previous records, most from the Auckland district of North Island, the Hammond collection provides much new distributional data. The three new species: Nellosana insperatus sp. n., Notoptenidium flavum sp. n., and Notoptenidium johnsoni sp. n., are described and figured; the genus Ptiliodes is moved from Acrotrichinae to Ptiliinae, and Ptenidium formicetorum Kraatz recorded as a new introduction. Information is provided to aid separation of the new species from those previously recorded.

scholarly journals Spatial Distribution of Lichens in Metrosideros excelsa in Northern New Zealand Urban Forests

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 170
Author(s):  
Gladys N. Benitez ◽  
Glenn D. Aguilar ◽  
Dan Blanchon
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
New Zealand ◽  
Lichen Species ◽  
Positive Correlation ◽  
Breast Height ◽  
Lichen Community ◽  
The North ◽  
The City ◽  
Lichen Flora

The spatial distribution of corticolous lichens on the iconic New Zealand pōhutukawa (Metrosideros excelsa) tree was investigated from a survey of urban parks and forests across the city of Auckland in the North Island of New Zealand. Lichens were identified from ten randomly selected trees at 20 sampling sites, with 10 sites classified as coastal and another 10 as inland sites. Lichen data were correlated with distance from sea, distance from major roads, distance from native forests, mean tree DBH (diameter at breast height) and the seven-year average of measured NO2 over the area. A total of 33 lichen species were found with coastal sites harboring significantly higher average lichen species per tree as well as higher site species richness. We found mild hotspots in two sites for average lichen species per tree and another two separate sites for species richness, with all hotspots at the coast. A positive correlation between lichen species richness and DBH was found. Sites in coastal locations were more similar to each other in terms of lichen community composition than they were to adjacent inland sites and some species were only found at coastal sites. The average number of lichen species per tree was negatively correlated with distance from the coast, suggesting that the characteristic lichen flora found on pōhutukawa may be reliant on coastal microclimates. There were no correlations with distance from major roads, and a slight positive correlation between NO2 levels and average lichen species per tree.

scholarly journals Strain-Rate and Grain‒Size Effects in Ice

1987 ◽  
Vol 33 (115) ◽  
pp. 274-280 ◽  
Author(s):  
David M. Cole
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Transition Point ◽  
Boundary Migration ◽  
Peak Stress ◽  
Strain Rates ◽  
Thin Sections ◽  
Fine Grained ◽  
Lower Strain ◽  
Polycrystalline Ice

AbstractThis paper presents and discusses the results of constant deformation-rate tests on laboratory-prepared polycrystalline ice. Strain-rates ranged from 10−7to 10−1s−1, grain–size ranged from 1.5 to 5.8 mm, and the test temperature was −5°C.At strain-rates between 10−7and 10−3s−1, the stress-strain-rate relationship followed a power law with an exponent ofn= 4.3 calculated without regard to grain-size. However, a reversal in the grain-size effect was observed: below a transition point near 4 × 10−6s−1the peak stress increased with increasing grain-size, while above the transition point the peak stress decreased with increasing grain-size. This latter trend persisted to the highest strain-rates observed. At strain-rates above 10−3s−1the peak stress became independent of strain-rate.The unusual trends exhibited at the lower strain-rates are attributed to the influence of the grain-size on the balance of the operative deformation mechanisms. Dynamic recrystallization appears to intervene in the case of the finer-grained material and serves to lower the peak stress. At comparable strain-rates, however, the large-grained material still experiences internal micro-fracturing, and thin sections reveal extensive deformation in the grain-boundary regions that is quite unlike the appearance of the strain-induced boundary migration characteristic of the fine-grained material.

Bismuth-bearing assemblages from the Northern Pennine Orefield

1996 ◽  
Vol 60 (399) ◽  
pp. 317-324 ◽  
Author(s):  
R. A. Ixer ◽  
B. Young ◽  
C. J. Stanley
Keyword(s):  
Qualitative Analysis ◽  
Fine Grained ◽  
Quartz Veins ◽  
The North ◽  
Data Form ◽  
Form Part ◽  
Native Bismuth ◽  
Monoclinic Pyrrhotite ◽  
Early Phases ◽  
And Tungsten

AbstractBismuthinite-bearing quartz veins from the Alston Block of the North Pennine Orefield are all close to, or above, the Rookhope and Tynehead cupolas of the buried Weardale Granite. They are uniform in composition and paragenesis and are earlier than the main fluorite-baryte-galena-sphalerite mineralization of the orefield. Rhythmical crystallization of quartz, chalcopyrite and minor pyrite is followed by fluorite-quartz-chalcopyrite-minor sphalerite-altered pyrrhotite mineralization. Early tin-bearing (up to 0.29 wt.% Sn) chalcopyrite encloses trace amounts of bismuthinite (Bi2S3), synchysite (CaREE(CO3)F2), argentopentlandite (Ag(FeNi)8S8) (close to being stoichiometric), pyrrhotite, cubanite and cosalite (Pb2Bi2S5), while early pyrite carries monoclinic pyrrhotite (close to Fe7S8) and tungsten-bearing cassiterite (up to 1.03 wt.% WO3). Bismuthinite is macroscopically visible and is associated with native bismuth and small, fine-grained, spherical aggregates that qualitative analysis suggests may be cosalite crystals. Synchysite and more rarely monazite, xenotime and adularia are intergrown with bismuthinite. These mineralogical data form part of the basis for an increasing awareness of the contribution of the Weardale Granite to the early phases of mineralization in the Alston Block.

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