Pressure-Transient Responses of Horizontal and Curved Wells in Anticlines and Domes
- Nasser Saqer Al-Mohannadi (Colorado School of Mines) | Erdal Ozkan (Colorado School of Mines) | Hossein Kazemi (Colorado School of Mines)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- February 2007
- Document Type
- Journal Paper
- 66 - 76
- 2007. Society of Petroleum Engineers
- 5.8.6 Naturally Fractured Reservoir, 5.2.1 Phase Behavior and PVT Measurements, 5.6.3 Pressure Transient Testing, 5.1 Reservoir Characterisation, 1.6.7 Geosteering / Reservoir Navigation, 5.6.4 Drillstem/Well Testing, 5.5 Reservoir Simulation, 5.1.1 Exploration, Development, Structural Geology, 1.6 Drilling Operations
- 3 in the last 30 days
- 760 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
This paper presents a discussion of the pressure-transient responses of horizontal wells in anticlinal structures and curved and undulating wells in slab reservoirs. It confirms that, in the absence of a gas cap, conventional horizontal-well models may be used to approximate the flow characteristics of the systems in which the trajectory of the well does not conform to the curvature of the producing structure. If a gas cap is present, however, the unconformity of the well trajectory and producing layer manifests itself, especially on derivative characteristics when the gas saturation increases around the well. In general, the most significant deviations from the conventional horizontal-well behavior are observed during the buildup periods following long drawdowns. In these cases, the pressure-transient analysis is complicated and requires detailed numerical modeling of the well trajectory and reservoir geometry in the vertical plane.
Conventional horizontal-well pressure-transient models assume that the top and bottom boundaries of the reservoir are horizontal planes; that is, the producing stratum is a slab, and the well is straight and parallel to the slab boundaries. Wells, however, may be drilled horizontally in anticlines and domes, or they may be curved or undulating in a horizontal slab reservoir.
In the literature, several reservoir shapes have been considered in the context of horizontal wells: infinite slab (Clonts and Ramey 1986; Ozkan et al. 1989; Goode and Thambynayagam 1987; Rosa and Carvalho 1989; Kuchuk et al. 1990, 1991; Ozkan and Raghavan 1990a), cylinder (Ozkan and Raghavan 1991a, 1991b), rectangular parallelepiped (Ozkan and Raghavan 1991a, 1991b; Daviau et al. 1988; Odeh and Babu 1990), and vertical no-flow boundary at an arbitrary orientation (Azar-Nejad et al. 1996a). The common feature of these reservoir models is the assumption that the top and bottom boundaries are horizontal planes. Despite the fact that the conditions at the top and bottom boundaries strongly influence the pressure-transient characteristics of horizontal wells (Clonts and Ramey 1986; Ozkan et al. 1989; Goode and Thambynayagam 1987; Ozkan 2001), the effect of the curvature of these boundaries, as in the case of anticlines and domes, has not been discussed in the literature.
Similar to the curvature of the top and bottom boundaries, the curvature or undulations of horizontally oriented wells (referred to as horizontal wells in this paper) have not attracted much attention in the pressure-transient-analysis literature. Two studies have addressed this issue specifically. Azar-Nejad et al. (1996b) considered a curved well that was a quarter of a circle (from vertical to horizontal) in a slab reservoir. They showed that especially in anisotropic reservoirs, the pressure-transient response of the curved well could not be approximated by that of a straight horizontal well of equal drilled length. This study did not address the issue of effective well length and the effect of the aspect ratio (the ratio of the distance from the well to the closest boundary and thickness of the formation).
Goktas and Ertekin (2003) discussed another common problem for horizontal wells—undulations. Their study indicated that when the vertical window of undulations becomes comparable to the formation thickness, undulations might influence the characteristics of pressure-transient responses. For practical windows of undulations that commonly result from standard drilling practices, however, the pressure-transient responses could be closely approximated by that of a straight horizontal well. This conclusion was different from that of Azar-Nejad et al. (1996b). It also must be noted that Goktas and Ertekin (2003) used the straight distance between the tips of the undulating well in the comparisons with straight horizontal wells, as opposed to the total drilled length used by Azar-Nejad et al. (1996b).
|File Size||1 MB||Number of Pages||11|
Al-Kobaisi, M., Ozkan, E., and Kazemi, H.2006. A HybridNumerical/Analytical Model of a Finite-Conductivity Vertical FractureIntercepted by a Horizontal Well. SPEREE 9 (4): 345-355.SPE-92040-PA. DOI: 10.2118/92040-PA.
Al-Mohannadi, N. 2003. Pressure-TransientAnalysis of Curvilinear Wells in Flat Structures and Horizontal Wells inAnticlines. PhD dissertation, Colorado School of Mines, Golden,Colorado.
Azar-Nejad, F., Tortike, W.S., and FarouqAli, S.M. 1996a. The Effect of theReservoir Geometry on Horizontal Well Performance. Paper SPE 37073presented at the SPE International Conference on Horizontal Well Technology,Calgary, 18-20 November. DOI: 10.2118/37073-MS.
Azar-Nejad, F., Tortike, W.S., and FarouqAli, S.M. 1996b. Performance ofHorizontal Wells with Irregular Geometry. Paper SPE 36550 presented at theSPE Annual Technical Conference and Exhibition, Denver, 6-9 October. DOI:10.2118/36550-MS.
Brooks, R.H. and Corey, A.T. 1964.Hydraulic Properties of Porous Media. Hydrology Papers, No. 3. Fort Collins,Colorado: Colorado State U.
Chaperon, I. 1986. Theoretical Study of Coning TowardHorizontal and Vertical Wells in Anisotropic Formations: Subcritical andCritical Rates. Paper SPE 15377 presented at the SPE Annual TechnicalConference and Exhibition, New Orleans, 5-8 October. DOI:10.2118/15377-MS.
Clonts, M.D. and Ramey, H.J. Jr.. 1986.Pressure Transient Analysis forWells With Horizontal Drainholes. Paper SPE 15116 presented at theCalifornia Regional Meeting, Oakland, California, 2-4 April. DOI:10.2118/15116-MS.
Daviau, F., Mouronval, G., Bourdarot, G.,and Curutchet, P. 1988. PressureAnalysis for Horizontal Wells. SPEFE 3 (4): 716-724.SPE-14251-PA. DOI: 10.2118/14251-PA.
Fleming, C.H., Gilman, J.R., and Kazemi,H. 1996. Testing of Horizontal Wells With Overlying Gas Cap. JPT48 (6): 533.
Fleming, C.H., Perschke, D.R., Gilman,J.R., and Kazemi, H. 1994. Pressure Transient Testing ofHorizontal Wells With an Overlying Gas Cap. Paper SPE 28391 presented atthe SPE Annual Technical Conference and Exhibition, New Orleans, 25-28September. DOI: 10.2118/28391-MS.
Giger, F.M. 1989. Analytic 2D Models of Water CrestingBefore Breakthrough for Horizontal Wells. SPERE 4 (4):409-416. SPE-15378-PA. DOI: 10.2118/15378-PA.
Goktas, B. and Ertekin, T. 2003. A Comparative Analysis of PressureTransient Behaviour of Undulating and Horizontal Wells. Paper SPE 81067presented at the SPE Latin American and Caribbean Petroleum EngineeringConference, Port-of-Spain, Trinidad and Tobago, 27-30 April. DOI:10.2118/81067-MS.
Goode, P.A. and Thambynayagam, R.K.M.1987. Pressure Drawdown andBuildup Analysis of Horizontal Wells in Anisotropic Media. SPEFE2 (4): 683-697; Trans., AIME, 283. SPE-14250-PA. DOI:10.2118/14250-PA.
Kuchuk, F.J., Goode, P.A., Brice, B.W.,Sherard, D.W., and Thambynayagam, R.K.M. 1990. Pressure-Transient Analysis forHorizontal Wells. JPT 42 (8): 974-979, 1028-1031.SPE-18300-PA. DOI: 10.2118/18300-PA.
Kuchuk, F.J., Goode, P.A., Wilkinson,D.J., and Thambynayagam, R.K.M. 1991. Pressure-Transient Behavior ofHorizontal Wells With and Without Gas Cap or Aquifer. SPEFE 6(1): 86-94; Trans., AIME, 291. SPE-17413-PA. DOI:10.2118/17413-PA.
Odeh, A.S. and Babu, D.K. 1990. Transient Flow Behavior of HorizontalWells: Pressure Drawdown and Buildup Analysis. SPEFE 5 (1):7-15; Trans., AIME, 289. SPE-18802-PA. DOI:10.2118/18802-PA.
Ozkan, E. 2001. Analysis of Horizontal-WellResponses: Contemporary vs. Conventional. SPEREE 4 (4):260-269. SPE-72494-PA. DOI: 10.2118/72494-PA.
Ozkan, E. and Raghavan, R. 1990a. Performance of Horizontal WellsSubject to Bottomwater Drive. SPERE 5 (3) 375-383;Trans., AIME, 289. SPE-18559-PA. DOI:10.2118/18559-PA.
Ozkan, E. and Raghavan, R. 1990b. A Breakthrough Time Correlation forConing Toward Horizontal Wells. Paper SPE 20964 presented at the EuropeanPetroleum Conference, The Hague, 21-24 October. DOI:10.2118/20964-MS.
Ozkan, E. and Raghavan, R. 1991a. New Solutions for Well-Test-AnalysisProblems: Part 1—Analytical Considerations. SPEFE 6 (3):359-368. SPE-18615-PA. DOI: 10.2118/18615-PA.
Ozkan, E. and Raghavan, R. 1991b. New Solutions for Well-Test-AnalysisProblems: Part 2—Computational Considerations and Applications.SPEFE 6 (3): 369-378. SPE-18616-PA. DOI:10.2118/18616-PA.
Ozkan, E., Raghavan, R., and Joshi, S.D.1989. Horizontal Well PressureAnalysis. SPEFE 4 (4): 567-575; Trans. AIME,287. SPE-16378-PA. DOI: 10.2118/16378-PA.
Ozkan, E., Sarica, C., and Haci, M. 1999.Influence of Pressure Drop Alongthe Wellbore on Horizontal-Well Productivity. SPEJ 4 (3):288-301. SPE-57687-PA. DOI: 10.2118/57687-PA.
Ozkan, E., Sarica, C., Haciislamoglu, M.,and Raghavan, R. 1995. Effect ofConductivity on Horizontal Well Pressure Behavior. SPE AdvancedTechnology Series 3 (1): 85-94. SPE-24683-PA. DOI:10.2118/24683-PA.
Peaceman, D.W. 1983. Interpretation of Well-BlockPressures in Numerical Reservoir Simulation With Nonsquare Grid Blocks andAnisotropic Permeability. SPEJ 23 (3): 531-543. SPE-10528-PA.DOI: 10.2118/10528-PA.
Rosa, A.J. and Carvalho, R.S. 1989. A Mathematical Model for PressureEvaluation in an Infinite-Conductivity Horizontal Well. SPEFE4 (4): 559-566. SPE-15967-PA. DOI: 10.2118/15967-PA.
Umnuayponwiwat, S. and Ozkan, E. 2000. Water and Gas Coning TowardFinite-Conductivity Horizontal Wells: Cone Buildup and Breakthrough. PaperSPE 60308 presented at the SPE Rocky Mountain Regional/Low-PermeabilityReservoirs Symposium and Exhibition, Denver, 12-15 March. DOI:10.2118/60308-MS.