A new approach in petrophysical rock typing

Abstract

Petrophysical rock typing in reservoir characterization is an important input for successful drilling, production, injection, reservoir studies and simulation. In this study petrophysical rock typing is divided into two major categories: 1) a petrophysical static rock type (PSRT): a collection of rocks having the same primary drainage capillary pressure curves or unique water saturation for a given height above the free water level, 2) a petrophysical dynamic rock type (PDRT): a set of rocks with a similar fluid flow behavior. It was shown that static and dynamic rock types do not necessarily overlap or share petrophysical properties, regardless of wettability. In addition, a new index is developed to define PDRTs via the Kozeny-Carman equation and Darcy's law. We also proposed a different index for delineation of PSRTs by combining the Young-Laplace capillary pressure expression and the Kozeny-Carman equation. These new indices were compared with the existing theoretical and empirical indices. Results showed that our indices are representatives of previously developed models which were also tested with mercury injection capillary pressure, water-oil primary drainage capillary pressure, and water-oil relative permeability data on core plugs from a highly heterogeneous carbonate reservoir in an Iranian oil field. This study enabled us to modify the conventional J-function to enhance its capability of normalizing capillary pressure data universally.

Effect of overburden pressure on determination of reservoir rock types using RQI/FZI, FZI* and Winland methods in carbonate rocks

“…Among these methods, RQI/FZI and Winland approaches are the most widely used techniques of rock typing (Winland 1972;Abbaszadeh et al 1996;Svirsky et al 2004;Biniwale 2005;Obeida et al 2007;Shenawi et al 2007;Chekani and Kharrat 2009;Ye et al 2011;Riazi 2018). However, as it is concluded from Mirzaei-Paiaman et al (2018), the RQI/FZI method completely fails in complicated cases such as heterogeneous rocks. Therefore, they suggested that using FZI* gives more reliable results.…”

“…Generally, petrophysical rock typing is categorized into two separate classes which are petrophysical static rock typing (PSRT) and petrophysical dynamic rock typing (PDRT). PSRT is defined as a group of rocks with a similar capillary pressure curve in the drainage process, whereas PDRT is described as a set of rocks that shows similar fluid flow behavior (Mirzaei-Paiaman et al 2018). Proper application of rock typing provides more real dynamic reservoir behavior in simulation models (Attar et al 2015;Saboorian-Jooybari et al 2015.…”

“…These techniques can be classified into two general groups: the theoretical and the empirical methods. The theoretical methods (such as rock quality index (RQI)/flow zone indicator (FZI) (Amaefule and Altunbay 1993), shale zone indicator (SZI) (Jongkittinarukorn and Tiab 1997;Nooruddin and Hossain 2011), modified FZI (Nooruddin and Hossain 2011), FZI* (FZIstar) (Mirzaei-Paiaman et al 2015) and FZI** (FZI-double star) (Mirzaei-Paiaman and Saboorian-Jooybari 2016) and PSRTI (Mirzaei-Paiaman et al 2018)) are basically derived from the well-known Kozeny-Carman equation. Empirical methods, such as Winland (Kolodzie Jr 1980;Pittman 1992;Aguilera 2002), generate relationships between porosity, permeability and a specific size of pore throat which is taken from mercury injection capillary pressure tests.…”

Improved reservoir characterization by employing hydraulic flow unit classification in one of Iranian carbonate reservoirs

“…The concept of flow unit has been developed as an in-tegrating tool for petrophysical description of the reservoir (Stolz et al, 2003;Izadi et al, 2012;Mirzaei-Paiaman et al, 2015, 2018. Based on this concept, rocks with similar petrophysical and flow properties are categorized within the same unit (Pittman, 1992;Amaefule et al, 1993;Soto et al, 2001;Kaydani et al, 2011;Ngo et al, 2015;Rabiller, 2017).…”

“…Different methods can be applied for interpreting the flow units and their corresponding petrophysical properties (Bagci et al, 2007;Banga et al, 2007;Schatz et al, 2007;Brigaud et al, 2014;Goda et al, 2014;Pyrcz et al, 2014;Rebelle, 2014). The amount and the type of information required by each method; however, varies depending on the data and the tools available (Jaya et al, 2005;Bagci et al, 2007;Askari et al, 2011;Rebelle, 2014;Tiab et al, 2015;Abdallah et al, 2016;Mirzaei-Paiaman et al, 2018). This may lead to different flow unit interpretation of the same reservoir.…”