Fluid Dynamics Quiz PDF

Fluid Dynamics Quiz Answers 1. Which factor influences the gross rock volume of a reservoir? A. Depositional environment B. Viscosity C. Formation volume factors D. Fluid compositions Answer: Depositional environment (A) The gross rock volume of a reservoir is influenced by factors such as the shape...

Fluid Dynamics Quiz Answers 1. Which factor influences the gross rock volume of a reservoir? A. Depositional environment B. Viscosity C. Formation volume factors D. Fluid compositions Answer: Depositional environment (A) The gross rock volume of a reservoir is influenced by factors such as the shape of the structure, dip of flanks, positions and throws of faults, and depths of fluid contacts (OWC, GOC). 2. Which characteristic of the fluids in a reservoir is important to consider? A. Net:Gross ratio B. Hydrocarbon saturation C. Porosity D. Gas:Oil ratio Answer: Gas:Oil ratio (D) Characteristics of the fluids in a reservoir, such as gas:oil ratio, fluid compositions, PVT properties, and formation volume factors, are important to consider for reservoir appraisal. 3. Which parameter is crucial to determine the hydrocarbon in place? A. Reservoir quality B. Depositional environment C. Capillary pressure D. Facies distributions Answer: Depositional environment (B) To determine the hydrocarbon in place, parameters such as reservoir quality, capillary pressure, depositional environment, and facies distributions need to be considered. 4. Which factor controls the gross rock volume of a reservoir? A. Depositional environment B. Facies distributions C. Diagenesis D. All of the above Answer: All of the above (D) The gross rock volume of a reservoir is controlled by the shape of the structure, dip of flanks, positions and throws of fault, depths of fluid contacts (OWC, GOC), as well as the depositional environment, facies distributions, and diagenesis. 5. What is the likely performance of the reservoir during production? A. Poor reservoir quality and heterogeneity B. High hydrocarbon production rates C. Compartmentalized structurally and/or stratigraphically D. Low hydrocarbon production rates Answer: High hydrocarbon production rates (B) The likely performance of the reservoir during production can be determined by factors such as reservoir quality, heterogeneity, pressure regime, presence of pressure support (aquifer, gas cap), and characteristics of the fluids. 6. What is the pressure regime in a reservoir? A. Pore pressure B. Hydrostatic pressure C. Overpressure D. Lithostatic pressure Answer: Pore pressure (A) The pressure regime in a reservoir includes hydrostatic pressure, lithostatic pressure, and pore pressure. Overpressure occurs when the pore pressure exceeds the hydrostatic pressure. 7. What is capillary pressure in a reservoir? A. Contact angle between two fluids and a solid B. Fracture pressure minus pore pressure C. Oil pressure minus water pressure D. Pressure difference between two fluids and a solid Answer: Oil pressure minus water pressure (C) Capillary pressure in a reservoir refers to the pressure difference between oil and water. It is calculated as the oil pressure minus the water pressure. 8. Which of the following is a characteristic of permeability? A. The ability of the fluid to flow through sand filters B. The concentration of Barium in the formation water C. The fraction of bulk volume occupied by void space D. The ability of the rock to transmit fluid Answer: The ability of the rock to transmit fluid (D) Permeability is a measure of how easily fluid can flow through a rock. 9. What is the equation for Darcy's Law? A. $q = \frac{2\pi kh(P_R - P_{wf})},{\mu \ln(re/rw)}$ B. $q = K(h_1 - h_2)$ C. $q = \frac{k \Delta P},{\mu L A}$ D. $q = PI(P_R - P_{wf})$ Answer: $q = \frac{k \Delta P},{\mu L A}$ (C) Darcy's Law relates the volumetric flow rate (q) to the pressure difference (ΔP), permeability (k), viscosity (μ), length (L), and cross-sectional area (A). 10. What is the main factor controlling porosity in a rock? A. Permeability B. Grain size C. Sorting D. Pore throats Answer: Grain size (B) The main factor controlling porosity in a rock is the grain size. 11. What is the productivity index (PI) used for in well testing? A. To calculate the flow rate of gas B. To measure the pressure drawdown in the reservoir C. To determine the flow rate of oil D. To evaluate the reservoir quality and heterogeneity Answer: To determine the flow rate of oil (C) The productivity index (PI) is used to determine the flow rate of oil in a well. 12. Which type of tests are performed during a DST? A. Closed tests only B. Neither closed nor open tests C. Both closed and open tests D. Open tests only Answer: Both closed and open tests (C) During a DST, both closed and open tests are performed and analyzed to estimate reservoir pressure, permeability, and size. 13. What is the term used to describe the time that decreases as real time increases in semilog plots of DST and production data? A. Build-up time B. Drawdown time C. Pressure time D. Horner time Answer: Horner time (D) In semilog plots of DST and production data, the term 'Horner time' is used to describe the time that decreases as real time increases. 14. What are the objectives of reservoir appraisal? A. Assessing reservoir performance and production rates B. Determining hydrocarbon in place and fluid compositions C. Analyzing pressure drawdown and build-up data D. Estimating reservoir pressure and permeability Answer: Assessing reservoir performance and production rates (A) The objectives of reservoir appraisal include determining the likely performance of the reservoir during production, assessing possible hydrocarbon production rates, and identifying structural and stratigraphic compartmentalization. 15. What is the significance of H2S and barium in the context of reservoirs? A. H2S affects hydrocarbon production rates and barium affects reservoir heterogeneity B. H2S affects fluid recovery and barium causes scale precipitation C. H2S affects reservoir quality and barium affects hydrocarbon saturation D. H2S affects reservoir pressure and barium affects fluid contacts Answer: H2S affects fluid recovery and barium causes scale precipitation (B) In the context of reservoirs, H2S is significant as it affects fluid recovery, while barium is significant as it causes scale precipitation. 16. Which equation represents the Young Laplace Equation? A. $PO - PW = \sigma(R1 - R2)$ B. $PO - PW = \sigma(R1 + R2)$ C. $PO - PW = \sigma(\frac{1}{R1} + \frac{1}{R2})$ D. $PO - PW = \sigma(\frac{1}{R1} - \frac{1}{R2})$ Answer: $PO - PW = \sigma(\frac{1}{R1} + \frac{1}{R2})$ (C) The Young Laplace Equation is given by $PO - PW = \sigma(\frac{1}{R1} + \frac{1}{R2})$, where $PO$ is the principal radii of curvature, $PW$ is the capillary pressure, and $\sigma$ is the interfacial tension. 17. Capillary pressure is defined as: A. oil pressure plus water pressure B. oil pressure minus water pressure C. water pressure minus oil pressure D. water pressure plus oil pressure Answer: oil pressure minus water pressure (B) Capillary pressure is defined as the difference between oil pressure and water pressure. 18. What is the relationship between capillary pressure and water saturation? A. Capillary pressure has no effect on water saturation B. For the same interfacial tension, smaller radius of curvature leads to higher capillary pressure C. Water saturation is inversely proportional to capillary pressure D. For the same interfacial tension, larger radius of curvature leads to higher capillary pressure Answer: For the same interfacial tension, smaller radius of curvature leads to higher capillary pressure (B) For the same interfacial tension, a smaller radius of curvature leads to higher capillary pressure, which in turn affects water saturation. 19. What is the purpose of a Repeat Formation Tester (RFT) in oil exploration? A. To record fluid pressure at different depths to establish likely fluid contacts B. To measure the porosity of a reservoir C. To calculate the net-to-gross ratio of a reservoir D. To determine the hydrocarbon saturation of a reservoir Answer: To record fluid pressure at different depths to establish likely fluid contacts (A) The purpose of a Repeat Formation Tester (RFT) in oil exploration is to record fluid pressure at different depths, which is then used to establish likely fluid contacts. 20. Which of the following tests are performed and analyzed during a DST? A. Both pressure drawdown and build-up B. Pressure drawdown only C. Pressure build-up only D. Neither pressure drawdown nor build-up Answer: Both pressure drawdown and build-up (A) During a Drill Stem Test (DST), both pressure drawdown and build-up tests are performed and analyzed to estimate reservoir pressure, permeability, and size. 21. What is the term used to describe the time that decreases as real time increases in semilog plots of DST and production data? A. Real time B. Ideal time C. Decreasing time D. Horner time Answer: Horner time (D) In semilog plots of DST and production data, the term 'Horner time' is used to describe the time that decreases as real time increases. 22. What is the main objective of reservoir appraisal? A. To evaluate reservoir performance and characteristics B. To analyze pressure drawdown and build-up data C. To determine hydrocarbon in place D. To estimate reservoir pressure Answer: To evaluate reservoir performance and characteristics (A) The main objective of reservoir appraisal is to evaluate the performance and characteristics of the reservoir, including factors such as hydrocarbon production rates, reservoir quality, pressure regime, and fluid characteristics. 23. What is the significance of H2S and barium in the context of reservoirs? A. They are indicators of reservoir quality B. They influence the gross rock volume C. They can cause issues such as toxicity and scale precipitation D. They affect the hydrocarbon saturation Answer: They can cause issues such as toxicity and scale precipitation (C) H2S is poisonous and corrosive, while barium is a major cause of scale precipitation. Therefore, their presence in reservoirs can cause issues and needs to be considered. 24. Which of the following is NOT a characteristic of permeability? A. Dependent on the size and shape of the rock pores B. Influenced by the viscosity of the fluid C. The ability of the rock to transmit fluid D. Controls the flow rate of fluids through the rock Answer: Influenced by the viscosity of the fluid (B) Permeability is not influenced by the viscosity of the fluid. It is solely dependent on the size and shape of the rock pores. 25. What is the equation for Darcy's Law? A. $q = \frac{K \Delta P},{\mu L A}$ B. $q = Kh_1 - h_2$ C. $q = \frac{K},{A}$ D. $q = \frac{\Delta P},{L}$ Answer: $q = \frac{K \Delta P},{\mu L A}$ (A) The equation for Darcy's Law is $q = \frac{K \Delta P},{\mu L A}$, where $q$ is the volumetric flow rate, $K$ is the filter-specific constant, $\Delta P$ is the pressure difference, $\mu$ is the fluid viscosity, $L$ is the length of the flow path, and $A$ is the cross-sectional area. 26. What is the likely performance of the reservoir during production? A. Low porosity and low permeability B. High porosity and low permeability C. High porosity and high permeability D. Low porosity and high permeability Answer: High porosity and high permeability (C) Reservoirs with high porosity and high permeability are likely to have good production performance, as they allow for the easy flow of fluids through the rock. 27. What is the purpose of a Repeat Formation Tester (RFT) in oil exploration? A. To estimate the hydrocarbon in place B. To measure the permeability of the reservoir C. To determine the pressure regime in the reservoir D. To collect fluid samples from the reservoir Answer: To collect fluid samples from the reservoir (D) The purpose of a Repeat Formation Tester (RFT) is to collect fluid samples from the reservoir. This helps in determining the fluid compositions and PVT properties of the reservoir fluids. 28. Which factor is NOT a control on gross rock volume in a reservoir? A. Facies distributions B. Capillary pressure C. Depths of fluid contacts D. Shape of structure Answer: Capillary pressure (B) Gross rock volume in a reservoir is controlled by the shape of structure, depths of fluid contacts, and facies distributions. Capillary pressure is not a control on gross rock volume. 29. What is the equation for pore pressure in a reservoir? A. $P_{Pore} = P_{Hydrostatic} - P_{Lithostatic}$ B. $P_{Hydrostatic} = \rho_{water} g h$ C. $P_{Lithostatic} = \rho_{bulk} g h$ D. $P_{Hydrostatic} \leq P_{Pore} \leq P_{Fracture}$ Answer: $P_{Pore} = P_{Hydrostatic} - P_{Lithostatic}$ (A) The equation for pore pressure in a reservoir is given by $P_{Pore} = P_{Hydrostatic} - P_{Lithostatic}$, where $P_{Hydrostatic}$ is the hydrostatic pressure, $P_{Lithostatic}$ is the lithostatic pressure, and $P_{Pore}$ is the pore pressure. 30. What is the equation for capillary pressure in a reservoir? A. $PC = (\rho_o - \rho_w)gh + P_{Pore}$ B. $PC = (\rho_o - \rho_w)gh$ C. $PC = P_{Hydrostatic} - P_{Lithostatic}$ D. $PC = P_{Hydrostatic} - P_{Pore}$ Answer: $PC = (\rho_o - \rho_w)gh$ (B) The equation for capillary pressure in a reservoir is given by $PC = (\rho_o - \rho_w)gh$, where $\rho_o$ is the density of oil, $\rho_w$ is the density of water, $g$ is the acceleration due to gravity, and $h$ is the height above the free water level. 31. What is the characteristic of reservoir rock wettability? A. Oil-wet B. Neither water-wet nor oil-wet C. Both water-wet and oil-wet D. Water-wet Answer: Water-wet (D) Reservoir rock is typically water-wet, meaning that it has a natural affinity for water. Over geological time, reservoir rock can become oil-wet, but initially, it is water-wet. 32. Which equation represents the relationship between capillary pressure and radius of curvature in the Young Laplace Equation? A. $PO - PW = \sigma(\frac{R2}{R1})$ B. $PO - PW = \sigma(\frac{R1}{R2})$ C. $PO - PW = \sigma(R1 + R2)$ D. $PO - PW = \sigma(\frac{1}{R1} + \frac{1}{R2})$ Answer: $PO - PW = \sigma(\frac{1}{R1} + \frac{1}{R2})$ (D) The Young Laplace Equation relates the capillary pressure ($PO - PW$) to the interfacial tension ($\sigma$) and the radii of curvature ($R1$ and $R2$) of the fluid-fluid interface. 33. Which of the following is true about drainage and imbibition in a reservoir? A. Drainage is the decrease of the non-wetting phase saturation, while imbibition is the increase of the non-wetting phase saturation. B. Drainage is the increase of the wetting phase saturation, while imbibition is the decrease of the wetting phase saturation. C. Drainage is the increase of the non-wetting phase saturation, while imbibition is the decrease of the non-wetting phase saturation. D. Drainage is the decrease of the wetting phase saturation, while imbibition is the increase of the wetting phase saturation. Answer: Drainage is the decrease of the wetting phase saturation, while imbibition is the increase of the wetting phase saturation. (D) Drainage refers to the process where the non-wetting phase (e.g., oil) increases its saturation through the largest pore throats, while imbibition refers to the process where the wetting phase (e.g., water) increases its saturation by expanding the grain edge film thickness and trapping the non-wetting phase. 34. What is the purpose of a Repeat Formation Tester (RFT) in oil exploration? A. To determine the hydrocarbon in place. B. To measure the pressure of the fluid present in the well. C. To establish the likely fluid contacts at different depths. D. To measure the porosity of the reservoir rock. Answer: To establish the likely fluid contacts at different depths. (C) A Repeat Formation Tester (RFT) is a tool used in oil exploration to measure the pressure of the fluid present in the well at different depths. These pressure measurements can then be used to establish the likely fluid contacts in the reservoir. 35. What is the main factor controlling the gross rock volume of a reservoir? A. Permeability of the reservoir rock. B. Interfacial tension of the fluid-fluid combination. C. Capillary pressure and water saturation. D. Depositional environment and facies distributions. Answer: Depositional environment and facies distributions. (D) The main factor controlling the gross rock volume of a reservoir is the depositional environment and the distribution of different facies within the reservoir rock. These factors determine the overall shape and size of the reservoir. 36. Which equation represents Darcy's Law, which describes the flow of fluid through a porous medium? A. $Q = \frac{kA}{\mu}\frac{\Delta P}{L}$ B. $Q = \frac{\mu A}{k}\frac{\Delta P}{L}$ C. $Q = \frac{kA}{\mu}\frac{L}{\Delta P}$ D. $Q = \frac{\mu A}{k}\frac{L}{\Delta P}$ Answer: $Q = \frac{kA}{\mu}\frac{\Delta P}{L}$ (A) Darcy's Law states that the flow rate (Q) through a porous medium is proportional to the cross-sectional area (A), permeability (k), and the pressure difference (ΔP), and inversely proportional to the fluid viscosity (μ) and the length (L) of the medium. 37. Which factor primarily controls the gross rock volume of a reservoir? A. Shape of structure B. Positions and throws of fault C. Depositional environment D. Facies distributions Answer: Shape of structure (A) The shape of the structure primarily controls the gross rock volume of a reservoir. Other factors such as the dip of flanks, positions and throws of fault, and depths of fluid contacts also play a role. 38. What is the main objective of reservoir appraisal? A. To identify structural and stratigraphic compartmentalization B. To determine the hydrocarbon in place C. To estimate the hydrocarbon production rates D. To assess the reservoir quality and heterogeneity Answer: To determine the hydrocarbon in place (B) The main objective of reservoir appraisal is to determine the hydrocarbon in place. Other objectives include assessing the reservoir performance during production, identifying compartmentalization, and evaluating the reservoir quality and heterogeneity. 39. Which equation represents the relationship between capillary pressure and water saturation? A. $P_c = \frac{{2\gamma}},{{r^2}}$ B. $P_c = \frac{{\gamma}},{{r}}$ C. $P_c = \frac{{2\gamma}},{{r}}$ D. $P_c = \frac{{\gamma}},{{r^2}}$ Answer: $P_c = \frac{{2\gamma}},{{r}}$ (C) The equation that represents the relationship between capillary pressure ($P_c$) and water saturation is $P_c = \frac{{2\gamma}},{{r}}$, where $\gamma$ is the interfacial tension between water and oil and $r$ is the radius of curvature of the meniscus. 40. What is the equation for pore pressure in a reservoir? A. $P_p = \rho gh$ B. $P_p = \frac{{\rho}},{{gh}}$ C. $P_p = \frac{{\rho g}},{{h}}$ D. $P_p = \frac{{\rho g}},{{h^2}}$ Answer: $P_p = \rho gh$ (A) The equation for pore pressure ($P_p$) in a reservoir is $P_p = \rho gh$, where $\rho$ is the density of the fluid, $g$ is the acceleration due to gravity, and $h$ is the height of the fluid column. 41. What is the equation for capillary pressure in a reservoir? A. $P_c = \frac{{\gamma}},{{r}}$ B. $P_c = \frac{{2\gamma}},{{r}}$ C. $P_c = \frac{{\gamma}},{{r^2}}$ D. $P_c = \frac{{2\gamma}},{{r^2}}$ Answer: $P_c = \frac{{\gamma}},{{r^2}}$ (C) The equation for capillary pressure ($P_c$) in a reservoir is $P_c = \frac{{\gamma}},{{r^2}}$, where $\gamma$ is the interfacial tension between two immiscible fluids and $r$ is the radius of curvature of the meniscus. 42. Which equation represents the relationship between capillary pressure and radius of curvature in the Young Laplace Equation? A. $PO - PW = \sigma( \ rac{R_1^2},{R_2^2} + \ rac{R_2^2},{R_1^2})$ B. $PO - PW = \sigma( \ rac{R_1},{R_2} + \ rac{R_2},{R_1})$ C. $PO - PW = \sigma( \ rac{1},{R_1} + \ rac{1},{R_2})$ D. $PO - PW = \sigma( \ rac{1},{R_1^2} + \ rac{1},{R_2^2})$ Answer: $PO - PW = \sigma( \ rac{1},{R_1} + \ rac{1},{R_2})$ (C) The Young Laplace Equation relates the capillary pressure difference between two fluids to the interfacial tension and the principal radii of curvature of the interface. 43. What is the characteristic of reservoir rock wettability? A. Water-wet B. Oil-wet C. Mixed-wet D. None of the above Answer: Mixed-wet (C) Reservoir rock can exhibit different degrees of wettability, ranging from water-wet to oil-wet, or a combination of both, known as mixed-wet. 44. What is the likely performance of the reservoir during production? A. High hydrocarbon production rates B. No hydrocarbon production C. Cannot be determined D. Low hydrocarbon production rates Answer: High hydrocarbon production rates (A) The likely performance of a reservoir during production depends on factors such as reservoir quality, porosity, and hydrocarbon saturation. A reservoir with high hydrocarbon production rates is more favorable. 45. Which factor is NOT a control on gross rock volume in a reservoir? A. Depths of fluid contacts B. Facies distributions C. Depositional environment D. Shape of structure Answer: Depositional environment (C) The gross rock volume of a reservoir is primarily controlled by the shape of the structure, depths of fluid contacts, and facies distributions. The depositional environment also plays a role, but it is not the main factor. 46. Which of the following factors primarily controls the permeability of a reservoir? A. Porosity B. Fluid composition C. Pressure regime D. Grain size Answer: Grain size (D) Permeability is primarily controlled by the grain size of the reservoir rock. Smaller grain sizes generally result in lower permeability. 47. What is the equation for Darcy's Law, which describes the flow of fluid through a porous medium? A. $q = \frac{\mu \Delta P A},{k L}$ B. $q = \frac{A \Delta P L},{\mu k}$ C. $q = \frac{k \Delta P A},{\mu L}$ D. $q = \frac{\mu A \Delta P},{k L}$ Answer: $q = \frac{k \Delta P A},{\mu L}$ (C) The equation for Darcy's Law is $q = \frac{k \Delta P A},{\mu L}$, where $q$ is the volumetric flow rate, $k$ is the permeability, $\Delta P$ is the pressure difference, $A$ is the cross-sectional area, $\mu$ is the viscosity, and $L$ is the length of the porous medium. 48. What is the main objective of reservoir appraisal? A. To measure the pressure regime in the reservoir B. To determine the permeability of the reservoir C. To estimate the hydrocarbon reserves in the reservoir D. To analyze the fluid composition of the reservoir Answer: To estimate the hydrocarbon reserves in the reservoir (C) The main objective of reservoir appraisal is to estimate the hydrocarbon reserves in the reservoir. This involves assessing the volume of recoverable hydrocarbons and their distribution within the reservoir. 49. What is the purpose of a Drill Stem Test (DST) in oil exploration? A. To estimate the porosity of the reservoir B. To determine the fluid composition of the reservoir C. To measure the permeability of the reservoir D. To evaluate the productivity of the reservoir Answer: To evaluate the productivity of the reservoir (D) The purpose of a Drill Stem Test (DST) is to evaluate the productivity of the reservoir. It involves temporarily isolating a section of the wellbore and measuring the flow rate and pressure of the reservoir fluids to assess the potential for production. 50. Which factor primarily controls the net-to-gross ratio in a reservoir? A. Facies distributions B. Diagenesis C. Depositional environment D. Hydrocarbon saturation Answer: Depositional environment (C) The net-to-gross ratio in a reservoir is primarily controlled by the depositional environment, which determines the distribution of facies and the diagenetic processes that affect the rock. 51. What is the equation for calculating pore pressure in a reservoir? A. $P_{Hydrostatic} = \rho_{bulk}g$ B. $P_{Hydrostatic} = \rho_{bulk}gh$ C. $P_{Hydrostatic} = \rho_{water}gh$ D. $P_{Hydrostatic} = \rho_{water}g$ Answer: $P_{Hydrostatic} = \rho_{water}gh$ (C) The equation for calculating pore pressure in a reservoir is $P_{Hydrostatic} = \rho_{water}gh$, where $\rho_{water}$ is the density of water, $g$ is the acceleration due to gravity, and $h$ is the depth. 52. What is the equation for capillary pressure in a reservoir? A. $PC = (\rho_o + \rho_w)gh$ B. $PC = (\rho_o - \rho_w)g$ C. $PC = (\rho_o + \rho_w)g$ D. $PC = (\rho_o - \rho_w)gh$ Answer: $PC = (\rho_o - \rho_w)gh$ (D) The equation for capillary pressure in a reservoir is $PC = (\rho_o - \rho_w)gh$, where $\rho_o$ is the density of oil, $\rho_w$ is the density of water, $g$ is the acceleration due to gravity, and $h$ is the height above the free water level. 53. What is the relationship between capillary pressure and water saturation in a reservoir? A. Capillary pressure decreases as water saturation decreases B. Capillary pressure increases as water saturation increases C. Capillary pressure decreases as water saturation increases D. Capillary pressure increases as water saturation decreases Answer: Capillary pressure increases as water saturation decreases (D) The relationship between capillary pressure and water saturation in a reservoir is that capillary pressure increases as water saturation decreases. This is due to the capillary forces that act to retain the water in the reservoir rock. 54. Which of the following is NOT a factor that influences the gross rock volume of a reservoir? A. Capillary pressure B. Shape of structure C. Depositional environment D. Positions and throws of fault Answer: Capillary pressure (A) The gross rock volume of a reservoir is controlled by the shape of the structure, dip of flanks, positions and throws of fault, and depths of fluid contacts. Capillary pressure is not a factor that influences the gross rock volume. 55. What is the equation for calculating the ideal permeability from semilog plots of DST and production data? A. $\Delta t = \frac{k},{tp}$ B. $\Delta t = \frac{tp},{\sqrt{k}}$ C. $\Delta t = \frac{tp},{k}$ D. $\Delta t = \sqrt{\frac{tp},{k}}$ Answer: $\Delta t = \frac{tp},{\sqrt{k}}$ (B) The equation for calculating the ideal permeability from semilog plots of DST and production data is $\Delta t = \frac{tp},{\sqrt{k}}$, where $\Delta t$ is the Horner time, $tp$ is the time for pressure build-up, and $k$ is the permeability. 56. What is the main purpose of well testing analysis methods? A. To measure flow rate and flowing bottom-hole pressure B. To analyze pressure drawdown and build-up data C. To determine the hydrocarbon in place and reservoir performance D. To estimate reservoir pressure, permeability, and size Answer: To analyze pressure drawdown and build-up data (B) The main purpose of well testing analysis methods is to analyze pressure drawdown and build-up data. This analysis is highly specialist and evolving rapidly. 57. What is the equation for calculating the productivity index (PI) in well testing? A. $PI = \frac{q},{\Delta P}$ B. $PI = \frac{\mu},{k}$ C. $PI = \frac{k},{\mu}$ D. $PI = \frac{\Delta P},{q}$ Answer: $PI = \frac{q},{\Delta P}$ (A) The equation for calculating the productivity index (PI) in well testing is $PI = \frac{q},{\Delta P}$, where $q$ is the flow rate and $\Delta P$ is the pressure drawdown.