Yousif M. Makeen

Biomarkers and inorganic geochemical elements of Late Jurassic-Early Cretaceous limestone sediments from Banik Village in the Kurdistan Region, Northern Iraq: implications for origin of organic matter and depositional environment conditions

Late Jurassic-Early Cretaceous limestone sediments from Banik Village in the Kurdistan Region, Northern Iraq, were analysed based on a combined investigation of elemental composition and biomarker characterisation. These investigations were used to define the origin, type of organic matters and their relation to the environment conditions during deposition. The bulk geochemical characteristics indicated that the Late Jurassic-Early Cretaceous limestone sediments were deposited in a marine environment with calcium-rich seawater. Their biomarkers provide evidence for a major contribution by aquatic organic matter with a minor terrigenous organic matter contribution. This is confirmed by normal alkanes, hopanoids, steroids and related compounds of the saturated hydrocarbons. Moreover, the salinity stratification and relatively reducing bottom water conditions are evidenced in the Late Jurassic-Early Cretaceous limestone sediments, as identified from Sr/Br, V/Ni and Pr/Ph ratios. The occurrence of gammacerane biomarker in the analysed samples is also a strong indicator of reducing and salinity stratification during deposition. Therefore, a stratified water column with salinity and relatively anoxic bottom water conditions contribute to organic matter (OM) preservation.

Geochemical Characteristics of Crude Oils, their Asphaltene and Related organic Matter Source Inputs from Fula Oilfields

The oils were derived from alga organic matter, which was sourced from sediments deposited in a lacustrine environment under suboxic to relatively anoxic conditions and were generated from mature source rock with a wide range of maturity ranging from early to peak oil window. This is indicated by biomarker compositions based on saturated and aromatic fractions and bulk geochemical characteristics. Previous work by Makeen et al. (2013) on the Abu Gabra shales in the basin shows similar organic matter characteristics, palaeo-depositional environment and maturity, suggesting that the Fula oils are derived from the early Cretaceous Abu Gabra shales. This genetic relationship is also confirmed by the similarities in the structural moieties of the Fula oil asphaltenes and Abu Gabra shale kerogens (Makeen et al., 2015).

Kerogen: Classification and origin - A case study

A major challenge facing the oil and gas drilling operations is mitigating the encountered wellbore instability issues. Those can vary from loss circulations up to having stuck pipes or tools that may jeopardize well integrity and potentially lead to total loss of wells and assets. These problematic situations are even much more complicated in fractured reservoir environments where predicting the highly fracture zones is important. Analyzing such problems is critical for companies especially in developing offshore fields where one day lost time is in hundreds of millions of dollars. There are various data sources that help in determining the main culprit behind the loss circulation problems from core data, Image logs and well testing data. The field of rock mechanics emerged to connect those phenomena to reservoir rock properties and stress profiles. Coupling this with an intensive analysis of drilling parameters, logging, core testing and other existing wells data builds a work frame that helps in understanding the reasons behind wellbore failures and providing solutions to them. The field under investigation is a highly geo-pressured carbonate gas field. The field development called for drilling vertical and slightly deviated wells. During the field increments, sever loss circulation were encountered that resulted in lost drilling times estimated in millions of US dollars with rig cost up

Molecular Composition of Abu Gabra Organic-rich Sediments in the Fula Sub-basin, Muglad Basin (Sudan)

200,000/Day. Other drilling failures includes, stuck drill pipe and difficulties with logging response and log interpretation. The objective of this study is to investigate the wellbore instability events during drilling operations and explain it as a function of rock properties, in-situ earth stress. The role of natural fractures will be highlighted using available data. During the course of the study, existing field’s and drilled wells available data, seismic data will be analyzed in order to come up with methods to map the loss circulation events and recommendations will be made for future wells drilling programs as well as future work to be carried.W the development of oil exploration, there is more and more ambiguity in the conventional logging interpretation. Although complex reservoirs and oil content identification can be analyzed and predicted by means of traditional neural network, there are some defects in information amalgamation especially when resolving different nonlinear problems. So we design a modified self-organizing neural network algorithm for qualitative attributes reduction integrated with rough set. Firstly log data with some qualitative attributes are analyzed in an information system from a view of fuzzy set, and then the key attributes from the interacted attributes with oil-bearing formation are extracted. Secondly unscented particle filtering(UPF) are used in estimating the parameters of the self-organizing fuzzy neural network, finally the experiments demonstrate that our algorithm can solve the predicting problems of nonlinear system with constraints, and extracts the if-then fuzzy rules in oil field with the less attributes and higher accuracy. The approach also shows rapid computing speed and strong anti-disturbance capacity. It will be verified to be suitable for lithology recognition and oil log interpretation in actual environments.

Organic geochemical and petrographic characteristics of Tertiary coals in the northwest Sarawak, Malaysia: Implications for palaeoenvironmental conditions and hydrocarbon generation potential

SUMMARY The Abu Gabra sediments possess a very good oil-generative potential as suggested by high amounts of organic matter with high TOC values in the range of 1.3 to 8.3 % that is dominated by Type I and Type II oil-prone kerogens. This is indicated by a significant presence of alginite and amorphous organic matter and supported by HI values in the range of 287-865 mg HC/ g TOC. Vitrinite reflactence (0.60-0.72%Ro) and Tmax values (430–438oC), and biomarker thermal maturity parameters indicate that the Abu Gabra sediments have entered an early mature of oil window. The predominance of even-over-odd (n-C14 to nC20) with significant presence of waxy n-alkanes (+n-C23) and with isoprenoids Pr/Ph ratios in the range of 1.17-2.51, indicating that these sediments were deposited in a suboxic, lacustrine environment that received both algal/bacterial and terrigenous organic matter input.