01-Semilog Analysis for Oil Wells

01-Semilog Analysis for Oil Wells - Semilog Analysis for...

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Semilog Analysis for Oil Wells 1
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Semilog Analysis for Oil Wells 2 Upon completion of this section, the student should be able to: 1. Analyze a constant-rate drawdown test using semilog analysis. a. Identify the data that correspond to the middle time region on the diagnostic plot. b. Calculate permeability and skin factor from a semilog graph. 2. Analyze a buildup test following a constant-rate flow period using the Horner method. a. Calculate the Horner pseudo-producing time for variable rate production. b. List the conditions that must be satisfied for the Horner pseudo-producing time to be applicable without referring to the text. c. Identify the data that correspond to the middle time region on the diagnostic plot. d. Calculate permeability, skin factor, and initial pressure from a Horner graph for a buildup test in a well in an infinite-acting reservoir.
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Semilog Analysis for Oil Wells 3
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Semilog Analysis for Oil Wells 4 Note that the skin factor affects the pressure response only within the altered zone. The pressure profile at points beyond the radius of the altered zone is not affected by the skin factor. We have already seen that the additional pressure drop due to skin at the wellbore can be calculated from the flow rate and fluid and rock properties. We can modify the Ei-function solution to apply for 2 cases: 1) at the wellbore, and (2) beyond the altered zone.
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Semilog Analysis for Oil Wells 5 Neither of these expressions is valid within the altered zone. Neither of these expressions is valid until after the logarithmic approximation to the Ei-function becomes applicable throughout the altered zone.
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Semilog Analysis for Oil Wells 6 When < 0.01, we may use the logarithmic r c 948 2 w φμ < 0.01, we may use the logarithmic approximation to the Ei-function. This expression may be written in the same form as the equation of a straight line. kt t y ~ p wf ( 29 x ~ t log 10 m ~ kh qB 6 . 162 μ - b ~ s 869 . 0 23 . 3 r c k log kh qB 6 . 162 p 2 w t 10 i + - φμ μ -
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Semilog Analysis for Oil Wells 7 A graph of p wf vs. log 10 (t) should fall on a straight line. Slope m allows us to estimate permeability. Intercept b (which is usually referred to as p 1hr ), allows us to estimate skin factor s.
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Semilog Analysis for Oil Wells 8 Slope m (t 1 , p wf1 ), (t 2 , p wf2 ) are any two points on the straight line portion of the graph. Normally, t
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This note was uploaded on 04/05/2011 for the course PETE 689 taught by Professor Staff during the Spring '08 term at Texas A&M.

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01-Semilog Analysis for Oil Wells - Semilog Analysis for...

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