Comparison of Permeability from NMR and Production Analysis in Carbonate Reservoirs

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. ________________________________________________ AbstractSeveral issues come to mind in the pursuit of log-derived permeability. Two of them, often referred to in recent publications, are the accuracy of the parameter and the representative of this permeability. Permeability from nuclear magnetic resonance (NMR) logs is often compared to core, wireline formation tester mobility, drillstem test and production data. The variation in vertical and lateral extent of these different measurements can give valuable insight into reservoir behavior. Average matrix permeability can be estimated from wireline NMR measurements while the other methods can more accurately evaluate the directional reservoir permeability as it varies with heterogeneities such as vugs, fractures, maximum horizontal stress and stylolites.Determining matrix permeability in carbonates from NMR data has been considered more difficult than in typical sandstone reservoirs. Recent developments in NMR carbonate analysis have provided insight as to how the permeability estimation from NMR logs can be improved. A method will be presented that overcomes some of the limitations of using NMR permeability in carbonates and will be compared with conventional NMR permeability estimation, core, wireline formation tester and drillstem test analysis in three Middle East carbonate reservoirs.

Application of nuclear magnetic resonance permeability models in tight reservoirs

“…Quintero et al improved the SDR model by introducing a weighting factor to the SDR model . The weighting factor is calculated by comparing the length of the fully saturated core plug relaxation distribution to the length of the fully saturated mud relaxation distribution.…”

“…A new permeability factor P f is introduced for the SDR equation, which can be calculated by the following equation: …”

Application of production logging tools in estimating the permeability of fractured carbonated reservoirs: A comparative study

“…Due to the fact that production logging tools investigate and evaluate the dynamic properties of the reservoir in the wellbore; in respect of the way, it is the reflection of absolute reservoir permeability (Quintero and Boyd, 1999;Sullivan, 2007;Faroognia et al, 2011). Thereby, the obtained permeability from these logs is fundamentally similar to realistic reservoir properties and act as the proper amount of permeability especially in fractured carbonated reservoirs which are considered as tight reservoirs in terms of creating dual permeability between matrix and fracture permeability.…”

NMR Logging tools providing better answers for hydrocarbon bearing reservoirs, North Western Desert, Egypt

“…In water saturated rocks, it can be proven mathematically that the decay curve associated with a single pore will be a single exponential with a decay constant proportional to pore size. The small pores have short T2 value and large pores have long T2 values Kenyon 1992, Chen et al, 1999, Quintero et al, 1999, Godefroy et al, 2001, Allen et al, 2001and Toumelin et al, 2002 . Because T2 values can be related to pore sizes, T2 value can be selected below which the corresponding fluids are expected to reside in small pores and above which the corresponding fluids are expected to reside in larger pores.…”