Quiz 6.pdf

Reservoir Appraisal and its Impact on Oil Production Answers 1. Which drilling operation involves modifying the density of drilling mud to match the pore pressure of the formation? A. Drilling out cement B. Cementing casing C. Mud circulation system D. Open Hole Answer: Mud circulation system (C) Th...

Reservoir Appraisal and its Impact on Oil Production Answers 1. Which drilling operation involves modifying the density of drilling mud to match the pore pressure of the formation? A. Drilling out cement B. Cementing casing C. Mud circulation system D. Open Hole Answer: Mud circulation system (C) The drilling operation that involves modifying the density of drilling mud to match the pore pressure of the formation is the Mud circulation system. 2. What equation is used to calculate the oil volume in place (STOIIP)? A. Gross-rock volume * Net:gross ratio B. Gross-rock volume / Net:gross ratio C. Porosity * Oil saturation D. Porosity / Oil saturation Answer: Gross-rock volume / Net:gross ratio (B) The equation used to calculate the oil volume in place (STOIIP) is Gross-rock volume / Net:gross ratio. 3. What is the purpose of steel casing in drilling operations? A. To determine the saturation of the formation B. To isolate formations with different pore pressure regimes C. To determine the porosity of the formation D. To modify the density of drilling mud Answer: To isolate formations with different pore pressure regimes (B) The purpose of steel casing in drilling operations is to isolate formations with different pore pressure regimes. 4. Which of the following is a consequence of drilling into a highly permeable formation with an insufficient mud weight? A. Increased sedimentation rate B. Overpressured sediments C. A blowout D. Drilling mud balance Answer: A blowout (C) Drilling into a highly permeable formation with an insufficient mud weight can lead to a blowout, which is a sudden and uncontrolled release of oil or gas. 5. What is the purpose of the density of drilling mud in the well bore? A. To generate overpressures B. To increase sedimentation rate C. To isolate well sections D. To balance the pore pressure in the formation Answer: To balance the pore pressure in the formation (D) The density of drilling mud in the well bore is designed to balance the pore pressure in the formation, preventing blowouts and maintaining stability. 6. What happens if the pore pressure exceeds the sum of stress and intrinsic tensile strength of the rock? A. The rock will fracture B. The rock will become overpressured C. The rock will become permeable D. The rock will erode Answer: The rock will fracture (A) If the pore pressure exceeds the sum of stress and intrinsic tensile strength of the rock, the rock will fracture, potentially leading to well integrity issues. 7. What is the purpose of casing in drilling wells? A. To balance the mud weight B. To increase pore pressure C. To isolate well sections D. To generate overpressures Answer: To isolate well sections (C) Casing is used to isolate well sections and maintain well integrity by preventing fluid migration and controlling pressure differentials. 8. Which factors control the gross rock volume of a reservoir? A. Reservoir quality, capillary pressure B. Formation volume factors, Gas:Oil ratio, viscosity C. Shape of structure, dip of flanks, positions and throws of fault D. Depositional environment, facies distributions, diagenesis Answer: Shape of structure, dip of flanks, positions and throws of fault (C) The gross rock volume of a reservoir is controlled by the shape of the structure, dip of flanks, and positions and throws of fault. 9. Which of the following is a factor that affects the net:gross ratio of a reservoir? A. Reservoir quality, capillary pressure B. Formation volume factors, Gas:Oil ratio, viscosity C. Depositional environment, facies distributions, diagenesis D. Shape of structure, dip of flanks, positions and throws of fault Answer: Depositional environment, facies distributions, diagenesis (C) The net:gross ratio of a reservoir is affected by the depositional environment, facies distributions, and diagenesis. 10. Which of the following is a factor that affects the porosity of a reservoir? A. Shape of structure, dip of flanks, positions and throws of fault B. Reservoir quality, capillary pressure C. Formation volume factors, Gas:Oil ratio, viscosity D. Depositional environment, facies distributions, diagenesis Answer: Depositional environment, facies distributions, diagenesis (D) The porosity of a reservoir is affected by the depositional environment, facies distributions, and diagenesis. 11. Which of the following is a factor that affects the oil saturation of a reservoir? A. Shape of structure, dip of flanks, positions and throws of fault B. Reservoir quality, capillary pressure C. Depositional environment, facies distributions, diagenesis D. Formation volume factors, Gas:Oil ratio, viscosity Answer: Reservoir quality, capillary pressure (B) The oil saturation of a reservoir is affected by the reservoir quality and capillary pressure. 12. Which of the following is the correct formula for calculating the Stock Tank Oil Initially In Place (STOIIP)? A. STOIIP = GRV * NTG * φ * SO * BO B. STOIIP = GRV * NTG * φ * SO + BO C. STOIIP = GRV * NTG * φ * SO / BO D. STOIIP = GRV * NTG * φ * SO * (1/BO) Answer: STOIIP = GRV * NTG * φ * SO * (1/BO) (D) The formula for calculating the Stock Tank Oil Initially In Place (STOIIP) is STOIIP = GRV * NTG * φ * SO * (1/BO), where GRV is the Gross Rock Volume, NTG is the Net:Gross Ratio, φ is the Porosity, SO is the Oil Saturation, and BO is the Formation Volume Factor. 13. What does the Gamma log measure? A. Electrical properties of rocks and fluids B. Natural radioactivity produced by the rock C. Velocity of sound waves through rock D. Hydrogen atom density Answer: Natural radioactivity produced by the rock (B) The Gamma log measures the natural radioactivity produced by the rock. It detects the presence of radioactive elements such as potassium, thorium, and uranium in sedimentary rocks. 14. Which logging tool can be used to measure the porosity of a formation? A. Dipmeter B. Resistivity logs C. Caliper D. Formation Density log Answer: Formation Density log (D) The Formation Density log can be used to measure the porosity of a formation. It measures the density of the rock, including the pore space, and can provide information about the porosity of the formation. 15. What is the formula for calculating the hydrocarbon saturation using Archie's Equation? A. Sw = (Rt / Rw) ^ (1/n) B. Sw = (Rw / Rt) ^ (1/n) C. Sw = (Rw * Rt) ^ (1/n) D. Sw = (Rt * Rw) ^ (1/n) Answer: Sw = (Rw / Rt) ^ (1/n) (B) The formula for calculating the hydrocarbon saturation using Archie's Equation is Sw = (Rw / Rt) ^ (1/n), where Sw is the water saturation, Rt is the formation resistivity, Rw is the resistivity of formation water, and n is the formation resistivity factor. 16. Which of the following is a drilling rig used for exploration drilling? A. Drillship B. Jack-up C. Semi-submersible D. All of the above Answer: All of the above (D) Exploration drilling rigs include drillships, jack-ups, and semi-submersibles. 17. What is the purpose of cementing steel casing in place during drilling operations? A. To isolate formations with different pore pressure regimes B. To measure the porosity of the formation C. To calculate the oil volume in place (STOIIP) D. To modify the density of drilling mud Answer: To isolate formations with different pore pressure regimes (A) Steel casing is cemented in place to isolate formations with different pore pressure regimes. 18. Which of the following factors affects the gross rock volume of a reservoir? A. Net:gross ratio B. Porosity C. Oil saturation D. All of the above Answer: All of the above (D) The gross rock volume of a reservoir is affected by factors such as the net:gross ratio, porosity, and oil saturation. 19. Which of the following is a consequence of drilling into a highly permeable formation with an insufficient mud weight? A. Decreased sedimentation rate B. Increased pore pressure C. Increased rock strength D. Decreased pore pressure Answer: Increased pore pressure (B) Drilling into a highly permeable formation with an insufficient mud weight can cause an increase in pore pressure. 20. What is the formula for calculating the hydrocarbon saturation using Archie's Equation? A. $S_w = \left(\frac{a},{\phi^m}\right)^{-n}$ B. $S_w = \left(\frac{\phi},{a^m}\right)^{-n}$ C. $S_w = \left(\frac{a},{\phi^m}\right)^n$ D. $S_w = \left(\frac{\phi},{a^m}\right)^n$ Answer: $S_w = \left(\frac{a},{\phi^m}\right)^{-n}$ (A) The formula for calculating the hydrocarbon saturation using Archie's Equation is $S_w = \left(\frac{a}, {\phi^m}\right)^{-n}$. 21. What is the purpose of steel casing in drilling operations? A. To isolate well sections with different mud weights B. To prevent blowouts C. To measure the porosity of a formation D. To balance the pore pressure in the formation Answer: To isolate well sections with different mud weights (A) The purpose of steel casing in drilling operations is to isolate well sections with different mud weights. 22. What happens if the pore pressure exceeds the sum of stress and intrinsic tensile strength of the rock? A. The rock will undergo compaction B. The rock will fracture C. The rock will become less permeable D. The rock will become more permeable Answer: The rock will fracture (B) If the pore pressure exceeds the sum of stress and intrinsic tensile strength of the rock, the rock will fracture. 23. Which of the following logging tools measures the hydrogen atom density of a formation? A. Gamma B. Density C. Neutron D. Electrical (SP, Resistivity) Answer: Neutron (C) The neutron logging tool measures the hydrogen atom density of a formation. 24. What is the formula for calculating the Stock Tank Oil Initially In Place (STOIIP)? A. STOIIP = GRV * NTG * φ* SO * (1/BO) B. STOIIP = GRV * NTG * φ* SO C. STOIIP = GRV * NTG * φ* (1/BO) D. STOIIP = GRV * NTG * φ Answer: STOIIP = GRV * NTG * φ* SO * (1/BO) (A) The formula for calculating the Stock Tank Oil Initially In Place (STOIIP) is STOIIP = GRV * NTG * φ* SO * (1/BO). 25. What is the equation used to calculate the hydrocarbon saturation using Archie's Equation? A. Sw = (Rt * φ) / (a * Rw) B. Sw = (Rt * φ) / (a * Rw) - (1 - φ) C. Sw = (Rt * φ) / (a * Rw) + (1 - φ) D. Sw = (Rt * φ) / (a * Rw) * (1 - φ) Answer: Sw = (Rt * φ) / (a * Rw) (A) The equation used to calculate the hydrocarbon saturation using Archie's Equation is Sw = (Rt * φ) / (a * Rw). 26. What is the formula for calculating the Ultimate Recovery (UR) of a reservoir? A. UR = STOIIP / RECOVERY FACTOR B. UR = STOIIP - RECOVERY FACTOR C. UR = STOIIP * RECOVERY FACTOR D. UR = STOIIP + RECOVERY FACTOR Answer: UR = STOIIP * RECOVERY FACTOR (C) The formula for calculating the Ultimate Recovery (UR) of a reservoir is UR = STOIIP * RECOVERY FACTOR. 27. Which of the following factors can affect the performance of a reservoir during production? A. The net:gross ratio B. The gross rock volume C. The pressure regime D. The hydrocarbon saturation Answer: The pressure regime (C) The pressure regime can have a significant impact on the performance of a reservoir during production. It determines if there is pressure support, such as from an aquifer or gas cap, which can enhance production rates. 28. What is the formula for calculating the Stock Tank Oil Initially In Place (STOIIP)? A. STOIIP = Gross Rock Volume * Net:Gross Ratio * Porosity / Oil Saturation B. STOIIP = Gross Rock Volume * Net:Gross Ratio / Porosity * Oil Saturation C. STOIIP = Gross Rock Volume / Net:Gross Ratio * Porosity * Oil Saturation D. STOIIP = Gross Rock Volume * Net:Gross Ratio * Porosity * Oil Saturation Answer: STOIIP = Gross Rock Volume * Net:Gross Ratio * Porosity * Oil Saturation (D) The formula for calculating the Stock Tank Oil Initially In Place (STOIIP) is STOIIP = Gross Rock Volume * Net:Gross Ratio * Porosity * Oil Saturation. 29. What is the purpose of the Net:Gross Ratio in reservoir appraisal? A. To determine the fraction of the volume that is productive B. To evaluate the pressure regime C. To estimate the ultimate recovery D. To calculate the hydrocarbon saturation Answer: To determine the fraction of the volume that is productive (A) The Net:Gross Ratio is used to determine the fraction of the volume that is productive in a reservoir. It helps in assessing the reservoir quality and heterogeneity. 30. What is the likely consequence of underestimating potential production rates in a reservoir? A. The cashflow will be lower than expected B. The infrastructure will be overdesigned C. The reservoir will be compartmentalized D. The reservoir quality will be poor Answer: The cashflow will be lower than expected (A) Underestimating potential production rates in a reservoir can lead to lower cashflow than expected. This is because the cashflow is directly influenced by the production design and rates. 31. Which of the following drilling rigs is designed to be moved from one location to another by towing or being carried on a barge? A. Drillship B. Jack-up C. Semi-submersible D. None of the above Answer: Jack-up (B) A jack-up drilling rig is designed to be moved from one location to another by towing or being carried on a barge. It has legs that can be lowered to the seabed to provide stability during drilling operations. 32. What is the purpose of the mud circulation system in drilling operations? A. To provide stability to the drill rig B. To control the density of the drilling mud C. To cool the drill bit D. To remove cuttings from the wellbore Answer: To remove cuttings from the wellbore (D) The mud circulation system is used to remove cuttings from the wellbore during drilling operations. It circulates drilling mud down the drill pipe, through the bit, and back up the annulus, carrying the cuttings with it. 33. Which of the following factors affects the porosity of a reservoir? A. Gross-rock volume B. Compaction factor C. Net:gross ratio D. Oil saturation Answer: Compaction factor (B) The compaction factor is a factor that affects the porosity of a reservoir. Compaction refers to the reduction in pore space due to the weight of overlying sediments, which can result in a decrease in porosity. 34. Which of the following is a consequence of drilling into a highly permeable formation with an insufficient mud weight? A. Decreased pore pressure B. Decreased sedimentation rate C. Increased pore pressure D. Increased sedimentation rate Answer: Increased pore pressure (C) Drilling into a highly permeable formation with an insufficient mud weight can lead to increased pore pressure, which can result in blowouts and other drilling hazards. 35. What is the formula for calculating the hydrocarbon saturation using Archie's Equation? A. $S_w = \left(\frac{a},{\phi^m}\right)^n$ B. $S_w = \left(\frac{a},{\phi^n}\right)^m$ C. $S_w = \left(\frac{\phi},{a^n}\right)^m$ D. $S_w = \left(\frac{\phi},{a^m}\right)^n$ Answer: $S_w = \left(\frac{a},{\phi^n}\right)^m$ (B) Archie's Equation is used to calculate the hydrocarbon saturation in a reservoir. The correct formula is $S_w = \left(\frac{a},{\phi^n}\right)^m$, where $S_w$ is the water saturation, $a$ is the formation factor, $\phi$ is the porosity, and $m$ and $n$ are empirical constants. 36. What is the purpose of the density of drilling mud in the well bore? A. To decrease the pore pressure in the formation B. To increase the pore pressure in the formation C. To balance the pore pressure in the formation D. To measure the pore pressure in the formation Answer: To balance the pore pressure in the formation (C) The density of the drilling mud in the well bore is designed to balance the pore pressure in the formation. This helps to prevent blowouts and other drilling hazards. 37. Which of the following factors can affect the performance of a reservoir during production? A. Pore pressure B. Fracture pressure C. Rock tensile strength D. All of the above Answer: All of the above (D) All of the above factors can affect the performance of a reservoir during production. Pore pressure, fracture pressure, and rock tensile strength are important parameters that can impact the flow of hydrocarbons in a reservoir. 38. Which of the following factors can affect the hydrocarbon in place in a reservoir? A. Depositional environment B. Reservoir quality C. Gas:Oil ratio D. Fault positions Answer: Depositional environment (A) Factors such as the depositional environment, fault positions, reservoir quality, and gas:oil ratio can all affect the hydrocarbon in place in a reservoir. 39. What is the purpose of the Net:Gross Ratio in reservoir appraisal? A. To assess the reservoir quality and heterogeneity B. To calculate the hydrocarbon saturation C. To estimate the hydrocarbon production rates D. To determine the fraction of the volume that is productive Answer: To determine the fraction of the volume that is productive (D) The Net:Gross Ratio is used to determine the fraction of the volume that is productive in a reservoir. 40. What is the likely consequence of underestimating the hydrocarbon production rates in a reservoir? A. The facilities will be overdesigned B. The fluids will have poor characteristics C. The reservoir will be structurally compartmentalized D. The cashflow will be less than expected Answer: The cashflow will be less than expected (D) Underestimating the hydrocarbon production rates in a reservoir can result in the cashflow being less than expected. 41. What is the formula for calculating the Stock Tank Oil Initially In Place (STOIIP) of a reservoir? A. $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BP)$ B. $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BO)$ C. $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BW)$ D. $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BG)$ Answer: $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BO)$ (B) The formula for calculating the Stock Tank Oil Initially In Place (STOIIP) of a reservoir is $STOIIP = GRV \times NTG \times \phi \times SO \times (1/BO)$. 42. Which of the following logging tools measures the porosity of a formation? A. Sonic B. Electrical (SP, Resistivity) C. Gamma D. Neutron Answer: Neutron (D) The Neutron logging tool measures the hydrogen atom density of a formation, which can be used to calculate the porosity of the formation. 43. What is the purpose of the Net:Gross Ratio in reservoir appraisal? A. To measure the hydrogen atom density of a formation B. To measure the natural radioactivity of a formation C. To measure the ratio of net reservoir volume to gross reservoir volume D. To measure the electrical properties of rocks and fluids Answer: To measure the ratio of net reservoir volume to gross reservoir volume (C) The Net:Gross Ratio is used to estimate the proportion of reservoir volume that is productive (net) compared to the total reservoir volume (gross). 44. What is the formula for calculating the hydrocarbon saturation using Archie's Equation? A. $Sw = \frac{R},{T} \phi$ B. $Sw = \frac{1},{R} \phi$ C. $Sw = \frac{R},{W} \phi$ D. $Sw = \frac{R},{W} \phi \frac{1},{RT}$ Answer: $Sw = \frac{R},{W} \phi$ (C) Archie's Equation is used to calculate the hydrocarbon saturation (Sw) of a formation using the resistivity of formation water (R), the porosity (φ), and the resistivity of the formation (W). 45. What is the formula for calculating the Stock Tank Oil Initially In Place (STOIIP)? A. $STOIIP = GRV * NTG * \phi * SO * (1/BO)$ B. $STOIIP = GRV * NTG * \phi * SO * BO$ C. $STOIIP = GRV * NTG * \phi * SO * (1/BO^3)$ D. $STOIIP = GRV * NTG * \phi * SO * (1/BO^2)$ Answer: $STOIIP = GRV * NTG * \phi * SO * (1/BO)$ (A) The Stock Tank Oil Initially In Place (STOIIP) is calculated by multiplying the Gross Rock Volume (GRV) by the Net to Gross Ratio (NTG), the porosity (φ), the oil saturation (SO), and the inverse of the formation volume factor (1/BO).