E-Core Analysis Applications

Tue, 01/22/2013 - 14:23

Understanding the geophysical and geochemical characteristics of a reservoir is essential to optimize production strategies for effective reservoir management. One adept technology for executing an in-depth analysis of rock formation and characteristics within a particular well is core analysis. DTK Group offers two different variants of core analysis technology: conventional core analysis and e-core analysis. Conventional core analysis consists of analyzing a core sample from a particular well to determine its characteristics. The results of the single sample analysis are then extrapolated to model the whole reservoir’s features. The technology has limitations, especially regarding the number of core samples extracted from the selected well. Each core gives a nine meter biopsy of the well’s petrophysical composition, which might not necessarily correlate with the key well sections that need to be scrutinized. While the response to this problem might reside in increasing the number of samples extracted, the cost implications of each core excision are high. This restricts the efficiency of the technology, also taking into consideration the fact that core analysis can take up to two years to be processed.

A solution to reduce the time and cost gap of conventional core analysis is e-core analysis, which can be based on sidewall core samples and drill cutting samples, apart from conventional core samples. Its microscopic imaging technology enables the company to recreate the internal structure of rocks and model them virtually. In the 3D model of the rock, petrophysical/single phase parameters are calculated, producing results on the porosity, absolute permeability, formation factors, elastic properties, and other sophisticated flow variables in weeks. The information is then extrapolated to constitute a network model, which helps in the calculation of two phase parameters, such as capillary pressure, relative permeability, and resistivity index, as well as the results of wettability sensitivity tests.

While Pemex has increased its requirements for core samples in some exploration wells from less than five to as much as 20, the new challenges that the NOC faces in the coming years demand a shift to e-core analysis. Operations on deepwater drilling rigs average higher expenses than conventional offshore or onshore operations. This translates into a higher overall cost to halt operations and take the time to extract conventional core samples. E-core provides the same information by doing analysis on samples that can be obtained without cutting a core, and this represents considerable financial savings.

The possible application of e-core analysis also extends to the future of unconventional reservoirs, with the necessity for a profound understanding of the different shale rock characteristics along the diverse geology of the country. Conventional core analysis of shale samples would be extremely time consuming and costly, resulting in questionable conclusions due to their zero permeability feature. Instead, e-core technology microscopically recreates the internal structure of a shale sample and enables its analysis even at extremely low permeability values in a shorter time and with better precision.

While e-core analysis is not a replacement for conventional core analysis, both technologies complement each other to better typify rock characteristics within reservoirs for a more refined understanding.