Decline-Analysis/Short Build-up Welltest Analysis of Low Permeability Gas Reservoir.

Abstract

The development increasingly involves reservoirs with low and ultra-low permeability reservoir. "Traditional" welltest analysis technologies in such reservoirs lose their efficiency (Davletbaev A.Y., Zhylko E. Y. etc. 2015, Loznyuk O.A. etc. 2015) as they require long-time shut-in (about 1 month and more), which causes huge losses in production (Davletbaev A.Y., Islamov R. R etc. 2015). In such conditions, analysis of usual operation data analysis and decline analysis become relevant (Arps J.J. 1945, Fetkovich M.J. 1980, Ilk D., Blassingame T.A. 2013, Doublet D.E. etc. 1994). This method has a lot of limitations, in particular, it is necessary to know the value of the reservoir pressure at the moment of the reservoir operation for interpretation, which is not always possible in the conditions of the operation and maintenance phase. The present work offers the method permitting to increase the informational content of the decline analysis, as well as to determine the value of initial reservoir pressure by combining «short» build-up welltest analysis with decline analysis in the operating well.

Application of rate transient analysis modeling in diagnosis of well abnormal flowing status in Middle East carbonate reservoir

“…In order to furtherly mitigate the noise inherent to the production data, NPI analysis plots a normalized pressure rather than a normalized rate (Song, 2011;Li et al, 2009Li et al, , 2016Ishkin et al, 2016;Basayir, 2018;Ataei et al, 2018;Wei, 2018;Han et al, 2016;Sunday et al, 2014;Wang et al, 2018). If we plot vs. on a Log-Log scale, the boundary-dominated flow will exhibit a unit slope line, similar to pseudo-steady state in Pressure Transient Analysis.…”