PETE 4190 Midterm Exam - Questions and Answers (Complete Solutions)

PETE 4190 Midterm Exam - Questions and Answers (Complete Solutions) In today's industry, the term ______ is typically used to describe any fine - grain sedimentary rock that require massive stimulation for economic rec ...

PETE 4190 Midterm Exam - Questions and Answers (Complete Solutions) In today's industry, the term ______ is typically used to describe any fine - grain sedimentary rock that require massive stimulation for economic recovery. Shale In today's industry, the term "shale" is typically used to describe any _________________________fine - grain sedimentary rock that require massive stimulation for economic recovery. In today's industry, the term "shale" is typically used to describe any fine - grain sedimentary rock that require massive stimulation for economic recovery. In this terminology shale rock may be composed of ____________ (smectite, illite, chlorite, kaolinite), quartz, feldspar, and carbonates. clay minerals In shales, ______ content varies between ~10 to 70% in these plays while the rest is _____ and ______. Clay; quartz; carbonates For which of the following rock mineralogy is more important? A. High permeability conventional reservoir B. Ultra-low permeability shale reservoir The mineralogy of shale rocks is very important for hydrocarbon recovery because rocks with less clay and more quartz and carbonates are more ______ and potentially comprised of _______________. brittle, larger pores More brittle rocks are ______ to fracture in hydraulic fracturing stimulation compared to ductile/ deformable rocks. Easier Many shale reservoirs are petroleum _____________, mainly characterized by low permeability less than 1 micro Darcy (μD). source rocks Many shale reservoirs are petroleum source rocks, mainly characterized by ___________________ less than 1 micro Darcy (μD). low permeability _____________________ (which are not source rocks) with permeabilities below 0.1 mD are also often categorized under shale reservoirs due to their need for extensive hydraulic fracturing to achieve economic production. Tight reservoirs Tight reservoirs (which are not source rocks) with permeabilities below 0.1 mD are also often categorized under ___________________ due to their need for extensive hydraulic fracturing to achieve economic production. shale reservoirs In short, the "shale" terms is more about the _____________ and extraction technology than the rock type and mineralogy. grain size In _____________ Mitchel Energy invested in shale. They drilled vertical wells and applied massive hydraulic fracturing. early 1980's Natural gas production from shale started to rise in the _____________ early 2000s Liquid-rich shales were more difficult to develop. Innovative fracture design in the Bakken, Eagle Ford, and Permian in _____________ resulted in significant production improvements. 2008-2012 Primary recovery factor of tight oil is ________ 5-8% Primary recovery factor of tight/shale gas is ___________ 5-20% Primary recovery factor of gas can exceed ___________ for conventional reservoirs 50-90% Primary recovery factor of oil is ________________ for conventional reservoirs 12-15% Secondary recovery factor of oil is ____________ for conventional reservoirs 15-20% Tertiary recovery factor of oil is ___________ for conventional reservoirs 4-11% Approximately ___________ of oil produced today are from primary recovery 37% Approximately 37% of oil produced today are from ___________________ primary recovery Shale hydrocarbon recovery was enabled by the introduction of hydraulic fracturing technology. A. True B. False False (shales were being produced before frac technology was available, mostly shale gas was being recovered) Liquid-rich shale recovery was enabled more recently than shale gas recovery. A. True B. False Liquid hydrocarbon at the surface implies that the hydrocarbon is in liquid state in the subsurface pore space. A. True B. False False (could be in the gas phase) ______ and ________ are the most common elements in living organisms. Accumulation of dead living beings -organic matter- occurs at the floor of oceans at a rate of a fraction of a millimeter per year. carbon, hydrogen The mix of the organic matter with mineral mud at ocean floor gets buried over time. The burial is accompanied by: (1) _________________________________ and (2) __________________________________ water expulsion and hardening of the mud into rock, temperature increase at an average rate of ~0.03° C per meter of burial. During burial, the temperature increases at an average rate of _______ 0.03 C per meter At shallow depths and temperatures up to 60° C, a small fraction of the organic matter is consumed by _____________________ micro-organisms (bacteria) At shallow depths and temperatures up to 60° C, a small fraction of the organic matter is consumed by micro-organisms (bacteria). After eating and digesting the organic matter, the bacteria give away a natural gas known as ______________ biogenic gas The solid residue of the organic matter known as ____________ turns into the oil and gas at higher depths. Kerogen At 2 - 4 km burial depth and 60 - 120° C temperature, the kerogen undergoes ________________ with increased hydrogen to carbon ratio. thermal cracking At temperatures near 60° C, the kerogen turns into _________, and upon further heating it turns into ____________________ as temperature gets closer to 120°. bitumen, heavy oil and then light oil At 4 to 6 km and 120 - 180° C, the kerogen turns into _______. Methane The hydrocarbons generated between 60 to 180° C are referred to as _________ oil and gas. Thermogenic The remaining kerogen above 180° C will be very rich in carbon and in solid state known as ______. Coal The temperature for oil to be generated at source rock is: A. 30 to 60 °C B. 60 to 120 °C C. 120 to 180 °C D. 180 to 230 °C The rock in which the organic matter turns into oil and gas is referred to as ___________ source rock The source rock has a very __________________ which enables it to retain the oil and gas generated in it for millions of years low permeability Burial of the source rock under kilometers of overlying sediments combined with the generation of lower density oil and gas causes the pressure in the source rock to significantly increase. As a result, the source rock cracks allowing oil and gas to _____________________ to overlying permeable formations. migrate upward Upward migration of oil and gas may continue all the way to the surface creating oil and gas ______________. Seepages Migrating oil and gas may be stopped by an impermeable layer, also known as a __________ caprock Migrating oil and gas may be stopped by an impermeable layer (caprock). The oil/gas then migrates updip along the caprock until it can no longer travel further updip e.g. because of encountering crest of an anticline or a sealing fault. The resulting accumulation of oil and gas in such a structure creates the ________________________. conventional reservoirs Tens of kilometers of migration is common for oil and gas to migrate from the source rock to the reservoir rock A. True B. False Conventional ultimate oil reserves are _____________________ - by including world oil consumption of 1.360 Tbbls to date and 1.7 Tbbls of global proved reserves. ~3 trillion bbls (Tbbls) While, hydraulic fracture technology works in the US, it may not work in other parts of the world especially in arid or semi-arid regions with water access problems. A. True B. False Permeability is proportional to grain size. That is, finer grains means lower permeability A. True B. False Roughly ______ percent of hydrocarbons remain in the source rock 50 Roughly 50 percent of hydrocarbons remain in the source rock. Out of the remaining 50% that migrates, _____ percent makes it to a conventional reservoir and ______ percent is lost (usually at the surface, ex: seepages) 5%, 45% The 5% of hydrocarbons that get trapped in conventional reservoirs are referred to as _____________ petroleum system yield (5%) The hydrocarbon resources in shale are 10 times those in conventional reservoirs. A. True B. False Assuming recovery factors of 10% for shale and 33% for conventional reservoirs, the hydrocarbon reserves in shale are 3 times larger than those in conventional reservoirs. A. True B. False