Deep transient testing methodology: An integrated approach to redefine the real-time reservoir complexities and well deliverability

Abstract Pressure transient analysis (PTA) forms a critical part of the reservoir characterization and quantitative evaluation of reservoir properties. In most of the cases, the pressure transient data are acquired by conventional drill stem tests (DST) to estimate fundamental reservoir properties like permeability, skin, and boundary, used for various well deliverability studies. However, with the emergence of cost optimization scenarios due to reduced crude oil prices in the market, and strict regulatory standards issued by the concerned governments, many exploration wells fail to pass the feasibility standards for a conventional full-scale drill stem test. At the same time, conventional formation testers couldn't help because of the limitation of its extremely low radius of investigation. The recent development of an improved wireline formation tester (WFT) version known as Deep Transient Tester (DTT) enables the industry to capture the far-field reservoir properties with a deeper investigation, complex reservoir heterogeneities, and possible boundary information. However, the acquired data needs advanced solution techniques for accurate interpretation of the information, which lacks at present. In the present study, we have showcased the development of a novel workflow that can interpret the deep transient testing data with better accuracy. The workflow is called Integrated Deep Transient Testing (IDTT). The IDTT workflow is the first of its kind, as per our knowledge, that utilizes both the analytical and numerical methods for the pressure transient analysis with advancements in each of them. The workflow has been validated by comparing results from three modes of testing DST, DTT, and WFT in a common well. Reservoir engineers can refer to the IDTT workflow to interpret the DTT pressure data to characterize reservoir properties, boundary information, and deliverability studies in simple to complex geological settings using the presently developed method.