Ali Al-Juboury

By A. I. Al-Juboury

Part of the book: Petrology

By Ali Ismail Al-Juboury, Waleed S. Shingaly, Elias M. Elias and Mohsin M. Ghazal

The samples of the mineralization of Pb-, Zn-, and Fe-sulfides were collected from three localities (Dure, Lefan, in the northern Thrust zone; and Sinjar, in the Foothill zone) in Northern Iraq. The geochemical recognition using X-ray diffraction (XRD) affirms the presence of the ore deposit sulfides (pyrite, sphalerite, galena, smithsonite, and cerussite). The characterization of mineral chemistry using electron microprobe analysis (EMPA) gives a clear and exact percentage of each element in each mineral. Fluid inclusions are mostly liquid H2O and/or water vapor, which may also contain lesser soluble salts and slightly ore elements. Some fluid inclusions contain CO2 vapor. This occurrence suggests the presence of two immiscible phases due to boiling at the time of their trapping. They are of epithermal system. The homogenization temperatures and salinities obtained for fluid inclusions can be comparable to those reported for the Mississippi Valley Type (MVT) lead-zinc deposits. It is concluded from the petrographic evidence, fluid inclusions and stable isotope data that lead-zinc mineralization was formed due to deeply circulating high-temperature fluids (brines) within the source basin, or later on by tectonic processes, which possibly contribute in leaching metals from either the diagenesis of host rocks or dewatering of deeper buried siliciclastic beds.

Part of the book: Contributions to Mineralization

By Ali Ismail Al-Juboury and Muhammed Abed Mazeel Thani

The Silurian hot shale is encountered in the Akkas field, which is regarded as one of the largest gas fields in Iraq. It contains 5.68 tscf of initial gas in place of which 4.55 tscf is estimated to be recoverable. There is also the potential of condensate and other prospects in deeper formations. The well test confirmed the presence of natural gas with a flow rate of 6–8 MMscfd. Silurian shale contains two organic-rich black hot shale beds that are fissile with high-gamma uranium radiation. Silurian hot shales are geologically important from different sides. Stratigraphically, Silurian graptolites are used to delineate the time transgressive depositional advance of marine clastics across the Arabian Peninsula after the melting of Ordovician glaciers. For assessment of the hydrocarbon generation in the Paleozoic of Iraq, the hot shales of the Akkas Formation are low-sulfur, high-gravity oil, condensate, and gas and are considered as an important gas-rich formation in the region. From petrological and mineralogical view, the presence of distinctive minerals and some elements are important to interpret the depositional and climatic situation at Silurian time. This chapter also sets out assumptions about Akkas gas field development.

Part of the book: Shale Gas

By Mohsin M. Ghazal, Ali I. Al-Juboury and Sabhan M. Jalal

Chalki basalts as a small body of volcanic rocks have green to grayish green color due to their nearly complete alteration to chlorite. The essential minerals of Chalki basalt to andesitic basalts are plagioclase (labradorite, An51–61; andesine, An35 to An42; and oligoclase, An22). Moreover, there is sodic plagioclase (albite, An0.1 to An04) whose coexistence with the other more calcic plagioclase means that albitization had occurred. The other essential mineral is pyroxene (endiopside, en66–68 wo27–28 fs05–06; and subcalcic augite, en72 wo14 fs14). Olivine (Fo80–81) is also present. According to the NiO content (0.11–0.12 wt%) in olivine grains, they are interpreted to be originated tectonically. The prevalent chlorite in all the samples is mainly diabantite and penninite, indicating chloritization after the ferromagnesian olivine and pyroxene. Serpentine (type lizardite and chrysotile) is also recorded as lesser alteration product after the forsteritic olivine. Rare secondary hornblende (type magnesiohornblende) is also found. The spinel group as accessory minerals is defined as magnetite, chromian magnetite, and chromian spinel giving the imprints of their metamorphic origin due to low temperature sub-sea metamorphism and also of alpine type.

Part of the book: Mineralogy

By Ali I. Al-Juboury, Rana A. Mahmood and Abulaziz M. Al-Hamdani

Evaporites (gypsum and anhydrite) of the middle Miocene age (Fat’ha Formation) form one of the main sulfate cap rocks in the Middle East oilfields. Detailed petrographic and diagenetic investigations accompanied with geochemical analysis of these evaporite rocks in Mosul and Kirkuk areas of northern Iraq have revealed that nodular gypsum is the dominant type, whereas laminated, structureless, and secondary (selenite and satin spar) also are present. Nodular gypsum was deposited in a very shallow, arid, and semi-restricted lagoonal environment which has undergone influx and reflux processes, while laminated gypsum may represent pulses of freshwater into the lagoonal basin of Fat’ha Formation. Low strontium values of the secondary and laminated gypsum may attribute to their secondary origin by hydration processes from the original anhydrite. Based on petrographic, diagenetic, and petrophysical (porosity and permeability) properties, it appears that the efficiency of the Fat’ha sulfates as petroleum cap rocks increases with increasing nodular growth and compaction degree. The occasional presence of bitumen inclusions with both nodular gypsum and host materials relates to early leakage of the hydrocarbons which were being halt due to the growing and packing of nodules and host materials.

Part of the book: Geochemistry

By Ali Al-Juboury, Mohammed A. Al-Haj and Aboosh H. Al-Hadidy

Stylolites are commonly observed in the carbonate reservoirs in various oilfield of Iraq including those of upper Cretaceous successions from northwestern Iraq, where they are characterized by stylolite-rich zones in the Cenomanian-early Turonian Gir Bir Formation and to a lesser extent in the Turonian-Santonian Wajna and early Campanian Mushorah formations respectively. The observed stylolites are either large to be identified in the core samples or smaller ones that are well observed in the thin sections and are characterized by variations in amplitude, morphology and accumulated insoluble residues. The recorded stylolites are classified as hummocky, irregular, low and high-amplitudes peaks, and irregular anastomosing stylolites. Stylolites affect the porosity permeability and thickness reduction compaction as the main chemical compaction (pressure solution) that reduce porosity. Whereas, in other places, the stylolites act as seals and stop the upward movement of hydrocarbons. This is also seen for mineralization processes such as silicification that ended near the stylolite surfaces.

Part of the book: Sedimentary Petrology