Goals of Well Analysis D Determination of the flowrate T To determine under what flow conditions well will cease to produce. o select the most economical time for the installation of artificial lift o optimize the well conditions and system geometry o analyze each component in the well system
5 porous media vertical well surface facility Separator Stock tank Sales Gas production system
Inflow performance relationship (IPR) is defined as the relation between the surface flowrate (q) and bottomhole flowing pressure (P wf ). Inflow Performance Relationship (IPR) IPR curves are used to analyze the deliverability of wells by estimating the production rate for a given bottomhole flowing pressure and vice versa and also reflect the ability of the reservoir to deliver fluid to the wellbore.
IPR Curve 1) Straight line (Constant PI) 1) Straight line (Constant PI) 2) A curve which shows that the PI is decreasing with rate 2) A curve which shows that the PI is decreasing with rate 3) A combination of 1 and 2. 3) A combination of 1 and 2.
Constant PI Production rate is proportional to the pressure drawdown Occurs for single phase liquid flow
Fetkovich’s Equation Using data from multirate tests on 40 different oil wells in six fields, Fetkovich showed that the following approach was suitable for predicting performance: where 0.5 ≤ n ≤ 1.0 This can be expressed in a form similar to Vogel’s IPR. (P r 2 – P wf 2 ) psia Flowrate ( q ) STB/d Log Log 1/n
IPR Curve for Multiphase Flow
Effective Parameters on Inflow Performance Dow point and bubble point pressure Reservoir pressure depletion Skin effect
Tubing Performance Relationship (TPR or VFP) Tubing performance may be defined as the behavior of a well in giving up the reservoir fluids to the surface. Flowing bottomhole pressure (tubing intake pressure) for each production rate equals total pressure drop through the tubing and any bottomhole restriction and wellhead pressure. P wh Q P wf relation between the surface flowrate (q) and (Pwf). relation between the surface flowrate (q) and tubing intake ressure(Pwf).
Pressure Drop In the Vertical Well Hydrostatic pressure drop Friction pressure drop
Change in phase behavior in the production tubing
Natural flow Accrue when the wellbore flowing pressure and tubing intake pressure (at perforation depth) are equal, TPR and IPR curves intersect together. The intersection of TPR and IPR curves called natural flow point.
Variables that Effects on Natural Flow Wellhead pressure Gas/liquid ratio Tubing size Static pressure &…
Effect of Wellhead Pressure
Effect of Gas/Liquid Ratio
Effect of Tubing Diameter
Effect of the Skin
Wellhead Performance By using of the wellhead performance can show in which range of flowrate in the well column, the hydrostatic pressure drop is more than friction pressure drop.
26 porous media Separator Stock tank Sales Gas production system vertical well
IPR & TPR & WPR P wh TPR WPR Rate Pressure IPR
Choke Performance The main function of a choke is to dissipate large amounts of potential energy (i.e., pressure losses) over a very short distance. Two types of two-phase flow can exist in a choke : Critical flow Subcritical flow P 1 = Wellhead ( upstream) pressure P 2 = downstream pressure P2/P1 ≤ %50 = R C P2/P1 > %50 = R C
CPR and WPR The intersection of the WPR and choke performance curve defines the rate of natural flow for the given choke size. The intersection of the WPR and choke performance curve defines the rate of natural flow for the given choke size.
Gilbert and Ros
Recommend Basic requirement for well performance analysis is the ability to determine, so it is required to determine BHP using surface data Basic requirement for well performance analysis is the ability to determine, so it is required to determine BHP using surface data Determine the best correlation to predict the fluid behavior in well column same as culender smite or duckler &… Determine the best correlation to predict the fluid behavior in well column same as culender smite or duckler &… Examine the quality of separator tests using daly reports of SPGC Examine the quality of separator tests using daly reports of SPGC