Posted Thursday September 25th, 2014, 10:31 am
A robust independent regional chemostratigraphic correlation has been constructed for the Jurassic to Cenozoic successions penetrated by onshore and offshore wells located along the entire length of the Tanzanian Indian Ocean margin, from well Pemba-5 in the north to wells Likonde-1 and Mnazi Bay-1 in the south. The correlation is based solely on interpretations of the inorganic geochemical data (derived from laterally extensive silty claystones) acquired from the aforesaid successions and is therefore not constrained by (but broadly comparable too) any previously published lithostratigraphic or biostratigraphic schemes. The study focuses on the differentiation and correlation of intervals within the syn-rift ‘Karoo succession (Megasequence MS1) which is penetrated in a some wells from the overlying continental break up – early drift Late Jurassic to Cretaceous sequence (Megasequence MS2) and the Cenozoic passive margin sequences (Megasequence MS1). Each of these sequences can be subdivided into up to 10 sequences and packages that can be correlated along the margin providing a high resolution stratigraphic framework that can used to calibrate wireline and seismic based correlations. Furthermore, the stratigraphy of the Cretaceous - Cenozoic successions is also complicated by the occurrence of unconformities, where significant parts of these successions are missing in some of the study wells. In addition, well defined lateral variations in the geochemistry of the Megasequence 3 successions have been noted, which are attributed to the detrital material discharged by the various ancient rivers having their own unique geochemical characteristics that can aid in the mapping of sediment dispersal patterns of individual deltaic-turbiditic systems. In addition to the chemostratigraphic correlation, the geochemical data have also been utilised to highlight stratigraphic and spatial variations in the geochemistry of the sedimentary rocks that can be related to changes in mineralogy and ultimately to variations in provenance.
The silty claystones are distributed across the entire coastal margin of Tanzania, but the sandstones are not laterally persistent and form localised lobes / sheets associated with deltaic complexes, shoreface deposits or turbidite fans. The sandstones occurring within each of the megasequences have similar geochemical characteristics, but the correlation of individual sandstone bodies is limited and tentative correlations of the Cenozoic sandstones have only proved possible between closely spaced wells.
The elemental data used to erect the chemostratigraphic zonations and correlation have also been utilised to predict the mineralogy (ChemMin) of all the analysed samples, which allows the construction of a mineralogical log for each study interval. The validity of the predicted mineralogy has been verified via selected mineralogical data acquired by XRD analyses. The advantage of this approach is that it effectively ‘transforms’ elemental data into mineral abundances, which are more readily understood by geologists, as well as generating a dataset that can highlight mineralogical changes over a well section and which can be employed to calibrate mineralogical models established by petrophysicists from E-log responses. The key commercial advantage is that ChemMin mineralogical logs can be derived from rapidly acquired geochemical datasets relating to large numbers of samples and wells. The results are consistent and, unlike XRD data, are not biased by using different contractors. The ChemMin logs provide a comprehensive summary in mineralogy so that clients can target sections for more time consuming and costly XRD or petrographic analysis if acquired. In addition, the logs provide a strong visual summary of the bulk mineralogy of the analysed successions in each well, as well as providing a means of quickly assessing which minerals principally control the E-log responses
Inorganic geochemical data can be employed to determine the redox conditions of the bottom waters at the time of deposition. Tribovillard et al. (2006) identified elements such as U, Mo, Cr, Co, Ni, Cu, S and Zn as being potentially useful for modelling variations in paleoredox conditions, as they are more soluble under oxidising conditions and less soluble under reducing conditions. Consistent anoxic intervals occur in the syn-rift silty claystones. Furthermore, anoxia and organic preservation have been recognised in the Middle Jurassic silty claystones and intermittently throughout the remainder of the Megasequence 2 successions identified in the study wells, these peaks probably reflecting localised and short-lived anoxic episodes. Analogous intermittent peaks of anoxia and organic preservation have also been observed over the Megasequence 3 intervals. To conclude, the study intervals display little evidence for the widespread preservation of abundant organic matter, thus they have no significant source potential.
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Posted Tuesday July 8th, 2014, 9:47 am
At the official opening of their new state-of-the-art laboratories and offices, 3rd July, Economy Minister Edwina Hart heard following a £500,000 investment in new facilities and equipment, the company was already creating jobs locally ahead of schedule as well as expanding its teams in Australia and the USA.
The expansion of their HQ, which was supported with £100,000 from the Wales Economic Growth Fund, has doubled the size of their facility on the Buttington Cross Enterprise Park, where eight new jobs have already been created, with another five in the pipeline.
Tim Pearce, Managing Director, said: “Over the last few years we have expanded rapidly. Our success is down to our commitment to R&D and the training and development of all our staff. We have ambitious plans for the future and we appreciate the continued support of Edwina Hart and the Welsh Government.
Opening their facilities today the Minister Edwina Hart said: “It’s great news to hear that Chemostrat, which operates in one of our key sectors, is making such an impact worldwide and continues to grow its business in Wales.
“Chemostrat works in a highly competitive field and I am delighted the Welsh Government is able to support its expansion and investment, enabling it to meet the increasing demand for its services around the globe.”
Chemostrat supports oil and gas exploration world-wide. It specialises in the analysis of rock samples, providing high quality interpretation of geochemical datasets for the petroleum industry using traditional and innovative technologies.
Funding support was also provided by the Welsh Government towards the purchase of two portable XRF (X-ray fluorescence) probes which will enable Chemostrat to provide
rapid, on site geochemical analysis of cores that is continuous and real time to aid companies with reservoir targeting.
The business founded in 1994 by Dr. Tim Pearce and Dr. Ken Ratcliffe in Welshpool currently employs 59 staff locally and an additional 18 in its offices in Houston, Perth and Calgary.
Posted Tuesday May 27th, 2014, 10:42 am
We were delighted to be visited last week by David Jones MP, Glyn Davies MP and Aled Davies. With £100,000 support from the Wales Economic Growth Fund, Chemostrat Ltd has recently expanded our laboratory and office space into adjacent premises, invested in state of the art equipment to enhance our analytical capabilities and created ten new highly skilled jobs.
The £500,000 investment doubles the size of our facility on Buttington Enterprise Park and allows the company to meet the growing global demand for its services.
Posted Monday May 12th, 2014, 2:48 pm
We have 3 speakers at the AAPG Conference this year
Wednesday 14th May
14:05 Sandtrak: a new tool to further the understanding of sands within reservoir systems
A. Finlay, I.Sevastjanova, C. Roach, T. Morgan, T. Pearce
14:30 Application of chemostratigraphy and palynostratigraphy to the Mississippian of well Siciny-2, Poland
D. A. Riley, D. McLean, L. Hubert, P. Zwoliński, R. Klischies, T. J. Pearce
Thursday 15th May
11:20 Inorganic geochemistry as a tool to improve the understanding of shale gas plays
T.R.Q. Morgan, A.J. Finlay, J. Martin
Posted Monday May 12th, 2014, 2:29 pm
Chemostrat are proud to announce the opening of our new offices in Calgary.
With a dedicated team of geologists based on the ground in Canada, we’re now even better placed to deliver mineralogical, elemental & magnetics data quickly and cost effectively.
At GeoConvention : FOCUS 2014 we will be show casing Sandtrak® - our integrated provenance solution.This adaptable multi-disciplinary workflow system is able to solve correlation and provenance problems at reservoir, field and basin scale. We will also have a selection of our portable equipment on display for you to find out just how quickly and cost effectively you can acquire mineralogical, elemental and magnetic data in remote locations. Come and find out how these services can be combined to provide solutions for your basin.
Chemostrat have had a significant input to several scientific papers that will be presented at GeoConvention this year, which are detailed below.
Monday 12th May
3pm - Correlation And Chronostratigraphy Of The Duvernay Formation: Elemental and Stable Carbon Isotope Stratigraphy
Sarah J. Porter, Gabriel Rotberg, Gemma Hildred, Barry Lees, Tim Pearce, James Griffiths
3.25pm - Evaluating And Supplementing XRD Results With Elemental Data: Mineral Modelling Examples From The Duvernay Formation
Gabriel L. Rotberg, Gemma V. Hildred, Tim Pearce
Tuesday 13th May
10.15am - So, how many sands does it take to make the McMurray Formation?
Jennifer J. Graham, Gemma Hildred, Tim Pearce, Inga Sevastjanova
Wednesday 14 May
3pm - Chemostratigraphic correlation within the Grand Banks, with a view of constraining sandstones for provenance analysis
Ceri Roach, Tim J Pearce & Barry Lees
Talking [email protected] Booth 910.
Monday 12th May
9.45am Stable Isotopes, bringing geochronology to shale correlations
4.30pm Portable solutions, economic data collection, anywhere, anyhow
Tuesday 13th May
9.45am Chemostratigraphy, elemental fingerprinting for high resolution correlation
4.30pm Sandtrak, tools to tackle the riddle of the sands
Wednesday 14th May
9.45am Rhenium Osmium, radio metric age dating in organic shales.