Oil Reservoirs


    Gas Maturity


Stable isotope analysis is a critical technique for upstream reservoir exploration through well profiling. Understanding the origin of oil and gas in any new reservoir is an essential requirement for determining its feasibility and suitability for exploitation. As well as making oil-oil correlations for reservoir mapping possible, stable isotope analysis is a key function of any petrochemical service laboratory.

Beyond the exploration of conventional reservoirs, recent plays into unconventional “tight” resources such as shale gas and coal bed methane have a similar need for stable isotope analysis; evaluation of the carbon and hydrogen fingerprints enables petroleum geochemists further insight into this continuing drive for new opportunities.

Oil fractions & natural gases

Compound specific isotope analysis allows highly precise isotopic profiling of oil reservoirs and therefore evaluation of the source of the oil. Knowing the origin of the oil and the extent of its maturity allows the feasibility of any well site to be established. Combined with carbon and hydrogen isotope analysis of natural gases, our exceptional GC-IRMS system and IonOS software, you will find that these time consuming analyses are performed quickly and rapidly, improving your ROI.

Whole oils & sediments

Combining compound specific isotope analysis of oil fractions with bulk isotope analysis is highly complementary for understanding oil origins, but also allows nitrogen, sulfur and oxygen isotope analysis of NSO fractions. Our elemental analysers also offer excellent performance for more refractory samples such as sediments which are able to bring greater insight into basin geochemistry.

Carbonates & DICs

By analyzing sedimentary carbonates from a basin brings greater understanding of the burial processes and diagenesis environment that the oil reservoir has been subjected too. Our iso FLOW system is able to analyse sedimentary carbonates, dissolved inorganic carbonate as well as well waters with high precision. This flexible system is also capable of analysing dissolved nitrates allowing complete hydrogeology of the basin to be established.

Oil & Gas publications using our instruments

Our customers use our instruments to do some amazing research in the oil & gas application field. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

43 results:

The effect of source and maturity on the stable isotopic compositions of individual hydrocarbons in sediments and crude oils from the Vulcan Sub-basin, Timor Sea, Northern Australia
Organic Geochemistry (2007)
Daniel Dawson, Kliti Grice, Robert Alexander, Dianne Edwards

Recent work has demonstrated the effect of maturation on the stable hydrogen isotopic compositions (δD) of individual sedimentary hydrocarbons (n-alkanes, pristane and phytane) in a series of marine source rocks from the Perth Basin (Western Australia). There was an enrichment in deuterium (D) in the hydrocarbons with increasing maturity, attributed to isotopic exchange associated with thermal maturation. An initial, large (≈115‰) biologically derived difference between the δD values of n-alkanes and isoprenoids gradually decreased as pristane and phytane became enriched in D, while the n-alkanes generally remained at constant isotopic composition. This work has now been extended to include a series of Late Jurassic sediments from the lower Vulcan Formation of the Vulcan Sub-basin (Timor Sea, Northern Australia), where the δD values of n-alkanes and isoprenoids show similar trends to those observed for the Perth Basin. The enrichment in D in isoprenoids correlates strongly with traditional maturity parameters and is shown to be related to the epimerisation of pristane and phytane. Pristane and phytane extracted from a post-mature Paqualin-1 sediment are significantly enriched in D relative to the n-alkanes, indicating that D enrichment persists at very high maturity, more so for regular isoprenoids than n-alkanes. This supports the notion that hydrogen (H/D) exchange causes the observed shift in δD values, and not free radical hydrogen transfer. A mechanism is proposed which can account for both H/D exchange and epimerisation of pristane and phytane in the sedimentary environment. Pristane is enriched in D relative to phytane throughout the Vulcan Sub-basin sequences, attributed to a lower relative algal input to the isoprenoids, and indicating that they exchange hydrogen at similar rates during maturation. Crude oils and condensates from the sub-basin were also analysed to evaluate their source and thermal maturity and the results complement previous molecular and stable carbon isotopic analysis. The δD values of n-alkanes and regular isoprenoids largely support the previous classification of Vulcan Sub–basin crude oils and condensates into two groups: Group A, having a marine source affinity and Group B, a terrigenous source affinity. Some oils and condensates are suggested to be a mixture of sources A and B, or A and other as yet unknown sources. Tenacious-1 crude oil (formerly a Group A oil) contains n-alkanes with more positive δD values than other Group A oils and is suggested to have been mixed with another source of more mature hydrocarbons. The Group A crude oils and condensates show an upward inflection in the n-alkane δD profile from n-C11 to n-C15, which is suggested to represent an addition of D-enriched lower molecular weight n-alkanes from a more mature wet gas/condensate to an initial oil charge. The small differences between the δD values of the n-alkanes and regular isoprenoids in the crude oils and condensates indicate that significant H/D exchange has taken place, implying that the samples were generated from mature source rocks.
Tags: carbon , hydrogen , geol , oilg , gaschrom

Geochemical and isotopic approach to maturitysourcemixing estimations for natural gas and associated condensates in the Thrace Basin, NW Turkey.pdf
Applied Geochemistry (2005)
Kadir Gurgey, R. Paul Philp, Chris Clayton, Hasan Emiroglu, Muzaffer Siyako

The Tertiary Thrace Basin located in NW Turkey comprises 9 km of clastic-sedimentary column ranging in age from Early Eocene to Recent in age. Fifteen natural gas and 10 associated condensate samples collected from the 11 different gas fields along the NW–SE extending zone of the northern portion of the basin were evaluated on the basis of their chemical and individual C isotopic compositions. For the purpose of the study, the genesis of CH4, thermogenic C2+ gases, and associated condensates were evaluated separately. Methane appears to have 3 origins: Group-1 CH4 is bacteriogenic (Calculated d13CC1–C = ?61.48&; Silivri Field) and found in Oligocene reservoirs and mixed with the thermogenic Group-2 CH4. They probably formed in the Upper Oligo- cene coal and shales deposited in a marshy-swamp environment of fluvio-deltaic settings. Group-2 (d13CC1–C = ?35.80&; Hamitabat Field) and Group-3 (d13C1–C = ?49.10&; Deg ˘irmenko ¨y Field) methanes are thermogenic and share the same origin with the Group-2 and Group-3 C2+ gases. The Group-2 C2+ gases include 63% of the gas fields. They are produced from both Eocene (overwhelmingly) and Oligocene reservoirs. These gases were almost certainly generated from isotopi- cally heavy terrestrial kerogen (d13C=?21&) present in the Eocene deltaic Hamitabat shales. The Group-3 C2+ gases, produced from one field, were generated from isotopically light marine kerogen (d13C=?29&). Lower Oligoce ne Mezar- dere shales deposited in pro-deltaic settings are believed to be the source of these gases. The bulk and individual n-alkane isotopic relationships between the rock extracts, gases, condensates and oils from the basin differentiated two Groups of condensates, which can be genetically linked to the Group-2 and -3 thermogenic C2+ gases. However, it is crucial to note that condensates do not necessarily correlate to their associated gases. Maturity assessments on the Group-1 and -2 thermogenic gases based on their estimated initial kerogen isotope values (d13C=?21&; ?29&) and on the biomarkers present in the associated condensates reveal that all the hydrocarbons including gases, condensates and oils are the products of primary cracking at the early mature st age (Req = 0.55–0.81%). It is demonstrated that the open-system source conditions required for such an early-mature hydrocarbon expulsion exist and are supported by fault systems of the basin.

Stable hydrogen isotopic composition of hydrocarbons in torbanites (Late Carboniferous to Late Permian) deposited under various climatic conditions
Organic Geochemistry (2004)
Daniel Dawson, Kliti Grice, Sue X Wang, Robert Alexander, Jens Radke

We measured the stable hydrogen isotopic composition ( D) of selected aliphatic compounds in torbanites from Scotland and Australia, covering the Late Carboniferous to the Late Permian. The torbanites contain organic matter predominantly from a single algal source, Botryococcus braunii, and are of similar thermal maturity. The D values of n-alkanes in the extracts appear to reflect the depositional palaeoclimate of each torbanite, in response to the typical D values of meteoric waters. The D values of n-alkanes in torbanites deposited at high latitude under glacial conditions are depleted in deuterium by up to 70% relative to n-alkanes in a torbanite deposited at low latitude under a tropical climate regime. Torbanites deposited in mid-latitude regions under cool-temperature conditions contain n-alkanes with D values between those of n-alkanes in tropical and glacial sediments. A saw-toothed profile of D values obtained for the n-alkanes in the Australian torbanites is attributed to a dual-source system, perhaps a predominant B. braunii input with a second minor contribution from land plants. Pristane and phytane from two Australian torbanites are significantly depleted in deuterium relative to n-alkanes in the same samples and a significant difference between the D values of pristane and phytane is suggested to be caused by different sources for the two isoprenoids, or isotope effects associated with their derivation from a common phytol precursor. The offset between the D of values of n-alkanes and isoprenoids is similar to that found in modern biological samples, indicating that their indigenous D signatures may have been preserved for at least 260–280 million years.