Reservoir Bible Questions

1. A commercial oil reservoir has recently been discovered. If the oil reservoir pressures above the bubble point pressure, the factor in material balance ….. far more important if the reservoir was producing below bubble point pressure:Produced GOR 2. An induced hydraulic fracture is aligned:Perpindicular to the minimum in situ stress direction 3. Based on Buckley-Leverett eq. What's the expected effect of capillary p.on microscopic displac.effic. of a water flooding? Decrease the microscopic displacment efficency. 4. Bucley Leverett equation: fw=(ko+ (koA/qtot*uo)*((Dpc/Dl)+g(ρw-ρo)*sinα)) / (1+ (kro/µo)*(µw/µrw)) 5. Considering a dynamic reservoir model, give 2 of the parameters need to be matched & 2 of the data can be used? WCT-> Kv,pc; HOIP->PHI, pc 6. Define apparent skin for gas wells: S'= S+Dgsc D=No darcy coefficient =kM/2πkhuR * (psc/Tsc)*[β'(1/rw - 1/r')+β(1/rw-1/r')] 7. Define the main features of injection fall off test. Why it is used as unconventional well testing?it's a press.trans.testing performed during injection of a fluid into a well. I't similar to drawdown testing for const. & variable rates.Shutting in an inject. well gives a press.falloff similar to press.build up in prod.well. A distintion from a drowdon/buildup test is made when the fluids injected are different. It's UNONCV. cause: 0 emission, no safety issues, mply equipment 8. Define the main features of MDT test. Why, it is used as an unconventional test?MDT havs a single probe or a dual parker configuration, and it's posssible test the fluid in an open cased hole by setting the parkers above and below the two interval ofinterest. It can be used to collect PVT sample, and it can be provide info about in situ fluid characteristics. In can be considered unconventional WT cause fluids are not produced tto surface, solving problem related to the handly of the fluid. 9. Describe briefly the static and dynamic model in reservoir: Static: consist of a conceptual&3D construction of a subsurface geological model. The 3D model describe:Structure,Stratigraphy,property of rock. Dynamic: it's a fluid flow similation, which workflow is composed by: Initialization, Hystory Matching, Forecasting,Evaluation of forecasting scenario (risk analysis). 10. Differences between static and dynamic model:Static (3D geolog.model) To investigate&model the res.structure&rock&fluid properties;Compute the HOIP;Make well trajectory planning. Dynamic (Fluid flow simul):Estimate recoverable resources&forecast the product. performaances;Select the best production scenario;Investigate all the possible improved recovery options 11. Eclipse initialization: 1)Datum depth,2)pressure@datum depth,3)GOC,4)WOC,5)Cp w-o,6)Cp g-o 12. Flow period is: Total period of time when well is producing 13. For an undersaturated oil reservoir, one equilibrium region is defined by: Initial press,datum depth,fluid contact,cp,PVT propert,°API 14. For which reasons the facies simulation is performed before the assignment of the petroph.proper? In order for the petroph.proper.to be distribuited according to a geological creiterion based on the facies distribut. 15. From operational point of view, conventional well testing consists of: 1)Imposing the surface rates;2)Measure of bottom hole pressure 16. Give the definition of reservoir: It's an subsurface body rock whit a sufficient permeability and porosity to store and trasmit hydrocarbons fluids and overlaid by a sealing rock that prevent hydr.to move upward 17. How can dual porosity be distinguished from dual permeabilty?Getting info on the reservoir geological environment 18. How can the formation fracture…..pressure be evaluated?From mini frac test carried out 19. How can we find sweep efficency? Sweep efficency is the rate between, the reservoir Area interested by thedisplacementfluid and the total area.It depend by the Mobility ratio,distance betwwen inj.wells, and the volume of injected fluid. 20. In a simulation model the hydros.equilib. Between 2 undersat.oil res.connected by the acquifer and with different OWC can be obtained by:Equal p &datum depth in the 2 regions@a depth deeper than the deepest OWC

21. In a typicall naturally fractured reservoir: Fluids are mainly stored in the matrix blocks and mainly flow along th fractures 22. In the case of monophase flow which of the following logs provides info bout the fluid entry points in a prod.well? Temperature logs 23. In the cut off analysis, the net-pay is obtained by applying: the cut off on shale volume, porosity &water saturation 24. In the definition of most appropiate orizontal grid cell dimensions(xy) in a 3D reserv.model,which issues must be taken in account? 1)Dimension of sedimentary bodies,3)Well spacing,4)Total numb.of cell 25. In the definition of most appropiate vertical grid cell dimensions in a 3D reserv.model,which issues must be taken in account? 1)Vertical eteroegenity,2) Presence of fault,3)Suspect of water coning,4)Total number of cell 26. In wich of the following steady state, flow occurs? Strong water drive (press=cost x presenza acquifero) 27. Indicate the term that wil NOT change the performance for an oil well:Water influx such as reservoir pressure remain const 28. Indicate what defines the correctness of the model initialization: Fluids equilibrium, static OHIP=dynamic OHIP 29. Investigation radius is: 1)Valid under transient conditions;2)A function of q;3)A function of K 30. List the main phase of numerical model/reservoir simulation:1)initialization,2)history matching,3)forecasting 31. List the main phase of reservoir static modelling: 1)Database creation &quality check,2)Stratigraphy well correlation&fluid contact&compartment identification 32. Logs: Fluid:Resistivity&Conductivity; Geology/lithology: Gamma ray;Porosity:Density&Neutron 33. Mechanical Skin correspond to: 1)Permeability reduction near wellbore;2)Lower well productivity 34. Plot the specilized plot and write the appropiate equation (Transient conditions): prw=pi-qu/4πkh * (ln2,25td+2S) 35. Select slope: Radial= 0; Linear=1/2;Bi-Linear=1/4; Spherical=-1/2 36. Should the press.derivat.indicate a slope equal to half?Horizontal well;Infinite conductvitity vertical fracture;parallel boundary(channel) 37. Simulation constrains apllied during a reservoir producation? Qo_MAX, Qin_MAX, GOR_MAX, WHP_MAX,BHP_min 38. Strong water drive is in a gas or oil reservoir? Oil reservoir 39. The assumption NOT used in the derivation of the Horner eq? Flow into wellbore continues after well shut in 40. The do nothing scenario is simulated: in the case of production reservoirs 41. The effect of shutting the well in, through a tester valve located down hole: WBS minimization 42. The end point scaling option can be used to apply: A variation of the relative permeability curves and/or cp curves in specific model areas 43. The parameter to calibrate in History matching are: Those affected by uncertain 44. To compare the production forecasts between 2 development scenarios of an oil reser. Which param. Are considered?Cumulative hydroc.productions &Gas, Oil, Water rates 45. To completely sustain the reservoir pressure in a producing oil reservoir through gas inj.,the water rate must be equal to: QgiBgi=QoBo+QwpBwp+QgfBgf 46. To completely sustain the reservoir pressure in a producing oil reservoir through water inj.,the water ratemust be equal to: QwiBwi=QoBo+QwpBwp+QgfBgf 47. What are the espected effects of decreasing the vertical permeability(anisotropy) in a dynamic reservoir model? delayed waterbreaktrough and decreasing water prod. 48. What are the espected effects of increasing the vertical permeability in a dynamic reservoir model? Anticipated waterbreaktrough and increasing water production 49. What are the influence of temperature on GOIP?No effect in the reservoir 50. What are the main objectives of WellTesting? 1)Estimate the reservoir k; 2)Estimate the

skin;3)Define remedial jobs;4) Estimate formation press. 51. What does a caliper log measure? WBS damage 52. What does the negative value of skin indicate? There is a permeability enhancment,i.e.stimulation, made by acidification 53. What is avarage pressure, and define all terms? P(av)=1/v∫pdv p(av)= pi-(qt/Ct*A*PHI*h) 54. What is history matching? Model calibration by matching real and simulated data by changing parameter model 55. What is the apparent skin? The apparent skin is the damage S' caused by the turbolence due by turbolent gas flow in the well. S'=S+Dqgsc, where D include: mechanical skin and geometrical skin 56. What is the equation of investigation radius? Rd=1,5*(kt/ct*PHI*u)^0,5 57. What is the log facies characterization?The assignment of lithological and petrohisical properties to the previously classified log-facies 58. What is the MBH function? 4π*tDA + ΣEi(-dj^2/4ηt) F dipende da: Shape of drainage area, Position of wells, Time tDA 59. What is the objective of reservoir simulation? To build 3D model that simulates the reservoir dynamic behaviour in order to forecast the field productivity according to different development scenario 60. What is the typicall behaviour of fluid flow in the fractured reservoir called due porosity? If S>0 (Restricted flow condit)There is a damage @ the interface of matrix and fissures, and the production is substained only by fissures through thehydrocarbons contained in it. If S=0 (Unrestric.flow.cond.)there is no damage @ the interface and the matrix, respond quickly to pressure variation, and feed the fissures with hydrocarb 61. What is the water cut? The percentage of water present respect the total liquid produced 62. Which are parameter affect WBS effect? Vw(volume of the well) & K(formation permeability) & C(compr.of the fluid) 63. Which are the main goals of areal interference test? AREAL: verify the continuiity between well,(drainage at the same level); VERTICAL:verify hydraulic communic. between 2 pools of the same well and reserv.commun.in the well. 64. Which are the main goals of limit test? Investigate on thedimensions of the reservoir 65. Which are the main types of unconventional well testing?1) Mini DST,2) Injection fall off test, 3)Closed chamber test,4) Downhole production reinjection 66. Which of the following are hydrocarbons traps? 1)Anticline,2)Fault,3)Statrigraphic,3)Salt dome 67. Which of the following are reservoir rocks?1)Clastic(sand,gravel), 2)Carbonate(limestone,dolomite) 68. Which of the following are sealing rocks?1)Salt, 2)Anydrite,3)Shale/clay 69. Which of the following combinations provides the highest efficency of an oil displacment process by water injection?Low mobility ratio, Low capillary pressure,Low krw, Low inj rate. 70. Which of the following workflow is correct?Fault modelling,horizontal modelling,internal zonation modelling,layering petrophisical modelling,upgridding&upscaling 71. Which parameter can be changed during history matching? Kabs,krel,cp,Acquifer parameters,Fluid contact,HOIP 72. Which parameters affect Dietz factor?: A (Shape of drainage area) & rw^2 (distance) 73. Why the knowledge of minimum in situ stress is important?It represent the press @ which the rock breaks 74. Wich pressure is normally measured by wirelin formation tester? Pressure of the dynamic mobile phase in the reserv. (Dynamic) 75. Write an equation describing the gas flow in a reservoir under transient cond.and define all terms: m(pi)-m(pw)=qsc*T*psc/2πkhTsc*(ln2,25*td+2S') td=tk/u*PHI*ct*rw^2 76. Write equation of pressure depletiond ue to production? Pi-P(avarage) = qt/ A*PHI*h*ct 77. Write the equation describing the gas flow in a reservoir area under early transient cond.and define all terms: m(pi)-m(pw)=qsc*T*psc/2πkhTsc*(ln2,25*td+2S') td=tk/u*PHI*ct*rw^2 78. Write the equation of Skin Factor: S= (k/k' -1)ln(r'/rw)

79. Write the Horner Equation: p(rw,t)=p*-(qu/(4πkh))*(log(tp+Δp/Δp)); if new well non in prod: p*=p OR p*=p(av) * (qu/4πkh)*F F:F function