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Insights From Interval Pressure Transient Tests Derive Key Fracture Parameters

The complete paper describes the shortcomings of traditional well testing methods and the methodology and results of applying wireline-conveyed IPTT in a light-oil reservoir offshore Norway. The study focuses on cases in which fractures are present in the near-wellbore region but do not intersect the wellbore. The study included parameters such as fracture densities and conductivities, distance between fractures and wellbore, and the vertical extension of the fractures across geological beds.

Introduction

Fractures can be first-order controls on fluid flow in hydrocarbon reservoirs. Understanding fracture characteristics such as aperture, density, distribution, conductivity, and connectivity is key for reservoir engineering and production analysis.

Well testing plays a key role in fracture characterization, particularly in fractured reservoirs. New advances in pressure transient analysis (PTA) have enabled the interpretation of production data such that the resulting geological scenarios are in better agreement with fracture patterns observed in outcrop analogs.

Traditionally, drillstem-test (DST) data have been the primary source of information for well testing. However, the authors hypothesized that wireline-conveyed tools designed for interval pressure transient testing (IPTT) could yield a more-thorough description of near-wellbore heterogeneities, including fractures. To prove their hypothesis, they used a next-generation wireline testing tool to investigate the applicability of IPTT for characterizing fractured reservoirs, using detailed numerical simulations models with accurate wellbore representation to generate synthetic IPTT responses. The effect of the different fracture scenarios on the pressure transient tests was recorded as characteristic signatures on diagnostic plots, which the authors call IPTT-geotypes because they can be used to assist the interpretation of IPTT responses.

The paper includes a field example of an IPTT case that was analyzed using the concept of geological well testing. Information from petrophysical logs and the IPTT-geotypes was integrated to assist the calibration of a reservoir model developed to represent the geological setting of the tested reservoir interval. The results provided a sound interpretation of the reservoir geology and quantitative estimation of the matrix and fracture parameters.

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 195435, “Macro Insights From Interval Pressure Transient Tests: Deriving Key Near-Wellbore Fracture Parameters in a Light-Oil Reservoir Offshore Norway,” by Alfredo Freites, SPE, Patrick Corbett, SPE, and Sebastian Geiger, SPE, Heriot-Watt University, et al., prepared for presentation at SPE Europec featured at the 81st EAGE Conference and Exhibition held in London, 3–6 June 2019.
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Insights From Interval Pressure Transient Tests Derive Key Fracture Parameters

01 February 2020

Volume: 72 | Issue: 2

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