A New Approach Formation Tester Interval Pressure Transient Test Design

Abstract

Increased deepwater drilling today requires that expensive and risky drillstem testing operations be optimized by other technologies that provide dynamic information about the formations to be tested. Wireline-conveyed interval pressure transient tests (IPTTs) are becoming a common practise today for optimizing and designing these expensive tests. Typically, prior to an IPTT, there is only a limited amount of information available about the reservoir and fluids properties and it tends to be generally probabilistic. Therefore, the optimal design of IPTT tests is a necessary challenge for a successful and reliable test. IPTT is found to be dependent on the noise and on observable flow regimes associated with the pressure buildups. Success and reliability are not only a function of gauge metrology but also of the formation deliverability and geometry. This paper describes a new methodology for IPTT design that allows estimation of the reliability of these transient tests. A normally distributed random noise is superimposed on the analytical pressure profile computed for a given formation, fluid PVT properties, and gauge metrology. The success of an IPTT in a particular environment is estimated based on the theoretical pressure derivative and noise-superimposed pressure derivative. This approach is repeated for a range of rock, and fluid properties and practical limits to identify what is a successful. Two field examples are presented to validate this methodology.

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“…The discrete spatial distribution of fracture and fault conductivities can be estimated from transient pressure *Address corresspondence to this author at the China University of Petroleum-Beijing, 18 Fuxue Road, Changping, Beijing China 102249; Tel: (86)01089733754; E-mail; taoguo@vip.sina.com measurements that are spatially distributed [6]. The dual packer module of wireline formation tester (interval pressure transient tests) provides pressure measurements in the near well bore, which can be about 10 ft to 30 ft depending on reservoir permeability [7]. The dual-packer module for an interval test straddles a fracture, a set of fractures, or a fault zone and makes direct measurements of effective conductivities.…”