Almost all wells eventually “feel” their boundaries. In Section 2-2 the steady-state condition implied a constant-pressure outer boundary. Naturally, this boundary can approximate the impact of a larger aquifer. Induced constant pressure may be the result of injector–producer configurations. For no-flow boundaries, drainage areas can either be described by natural limits such as faults, pinchouts, and so… Continue reading Pseudo steady-State Flow
Month: June 2023
Transient Flow of Undersaturated Oil
The diffusivity equation describes the pressure profile in an infinite-acting, radial reservoir, with a slightly compressible and constant viscosity fluid (undersaturated oil or water). This equation, with similar expressions in wide use in a number of engineering fields such as heat transfer (Carslaw and Jaeger, 1959), has the classic form Its generalized solution is where Ei(x)… Continue reading Transient Flow of Undersaturated Oil
Steady-State Well Performance
Steady-state performance means that all parameters, including flow rate and all pressures, are invariant with time. For a vertical well draining a region with radius re, this requires that the pressure at the well boundary, pe, and the bottomhole flowing pressure, pwf, are constant with time. Practically, the boundary pressure, pe, for a production well can remain constant only… Continue reading Steady-State Well Performance
Introduction
Well deliverability analysis predicts the wellbore flowing pressure for a given surface flowrate. Deal with well inflow performance and describe the reservoir variables that control well productivity under different conditions. Wells drilled in oil reservoirs drain a porous medium of porosity ϕ, net thickness h, and permeability k. To understand the process of flow from the reservoir and into… Continue reading Introduction
Units and Conversions
We have used “oilfield” units throughout the text, even though this system of units is inherently inconsistent. We chose this system because more petroleum engineers “think” in bbl/day and psi than in terms of m3/s and Pa. All equations presented include the constant or constants needed with oilfield units. To employ these equations with SI… Continue reading Units and Conversions
Well Productivity and Production Engineering
1.3.1. The Objectives of Production Engineering Many of the components of the petroleum production system can be considered together by graphing the inflow performance relationship (IPR) and the vertical flow performance (VFP). Both the IPR and the VFP relate the wellbore flowing pressure to the surface production rate. The IPR represents what the reservoir can… Continue reading Well Productivity and Production Engineering
The Surface Equipment
After the fluid reaches the top, it is likely to be directed toward a manifold connecting a number of wells. The reservoir fluid consists of oil, gas (even if the flowing bottom-hole pressure is larger than the bubble-point pressure, gas is likely to come out of the solution along the well), and water. Traditionally, the… Continue reading The Surface Equipment
The Zone near the Well, the Sandface, and the Well Completion
The zone surrounding a well is important. First, even without any man-made disturbance, converging, radial flow results in a considerable pressure drop around the wellbore and, as will be demonstrated the pressure drop away from the well varies logarithmically with the distance. This means that the pressure drop in the first foot away from the… Continue reading The Zone near the Well, the Sandface, and the Well Completion
Permeability
The presence of a substantial porosity usually (but not always) implies that pores will be interconnected. Therefore the porous medium is also “permeable.” The property that describes the ability of fluids to flow in the porous medium is permeability. In certain lithologies (e.g., sandstones), a larger porosity is associated with a larger permeability. In other… Continue reading Permeability
Areal Extent
Favorable conclusions on the porosity, reservoir height, fluid saturations, and pressure (and implied phase distribution) of a petroleum reservoir, based on single well measurements, are insufficient for both the decision to develop the reservoir and for the establishment of an appropriate exploitation scheme. Advances in 3-D and wellbore seismic techniques, in combination with well testing,… Continue reading Areal Extent