A numerical study of the pseudotime transformation for drawdown in the infinite-acting period

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · SPE (Society of Petroleum Engineers) Format. Eval.; (United States)

OSTI ID:5794900

Yue-lu, Y; Finjord, J

Drawdown with a constant-surface-conditions gas rate into a single well, starting at homogeneous pressure conditions in a cylindrical gas reservoir, is simulated numerically. For radii much larger than the wellbore radius, the pseudopressure solution in the infinite-acting period can be plotted uniquely as a function of a Boltzmann variable s=r/sup 2//sub D//4t/sub rhoD/, where r/sub D/ and t/sub rhoD/ are dimensionless radius and pseudotime. The nonlinear correction terms in the pseudotime diffusion equation, far from being negligible for drawdown, can become dominant in the infinite-acting period. This confirms an analytical result obtained previously. The correction terms are shown by simulation to be functions of s only for radii much larger than the wellbore radius. Plotted vs. In s, the pseudopressure shows an approximately linear behavior with a slope slightly larger than the usual constant-diffusivity slope. This was predicted by an explicit analytical solution.

• Research Organization: Rogaland Regional C. (NO)
• OSTI ID: 5794900
• Journal Information: SPE (Society of Petroleum Engineers) Format. Eval.; (United States), Journal Name: SPE (Society of Petroleum Engineers) Format. Eval.; (United States) Vol. 4:2; ISSN SFEVE
• Country of Publication: United States
• Language: English

Related Subjects

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03 NATURAL GAS
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CALCULATION METHODS
NATURAL GAS WELLS
NONLINEAR PROBLEMS
OIL WELLS
RESERVOIR PRESSURE
SIMULATION
WELLS