Let's Disrupt the Wireline Pressure Testing Practices, Shall We?
Authors: Garcia G. D. , Dumond H. , Mishra V. , Chen L. , Hayden R. , Babin C. 
Published: April 2019

A concept platform integrating the precise movement of a linear or azimuthal actuator, such as in instrumented wireline intervention tools (IWIT), with fast pressure measurement is presented. This device is intended to accurately move a measurement probe or sampling assembly either in the longitudinal or azimuthal direction in the wellbore to significantly improve data quality and operational efficiency.

Precise movement control enables acquiring data at exact intervals to eliminate errors induced by cable stretching, overpulls, or variable cable creep. Monte Carlo simulations of this concept using current IWIT capabilities suggest significant reduction of the pressure gradient uncertainty over common wireline protocols. The operational procedure includes correlation using standard wireline gamma ray logs, anchoring of the platform at the top of the interval to be tested and performing the distributed survey using a combination of tractors and linear actuators for every probe displacement. Removing cable movement significantly reduces an important source of error in distributed pressure measurements. These acquisition errors induce interpretation uncertainties like position of contacts and connectivity between flow units. These have profound impacts in exploration and appraisal decisions and field development plans.

This concept platform would enable reducing the time spent on pressure surveys if similar accuracy to current standard practices is acceptable. Because the remaining source of error is mostly due to gauge accuracy, results show that fewer stations are necessary to replicate standard wireline results. Where accuracy is important, as with distributed pressure measurements to quantify reserves using gradient intersection to define fluid contacts or determine compositional gradients, the proposed approach is shown to significantly reduce gradient error using the same number of stations. We use synthetic data sets built from previous work to show the impact of the error reduction in the position of the fluid contact.

IWITs currently used in cased hole employ active anchoring to perform intervention tasks. The controlled downhole force available for these operations goes up to 80,000 lbf while the anchoring force could be up to 150,000 lbf. In the proposed concept platform, this pulling force could be instrumental where there is high risk of differential sticking. By anchoring the upper part of the platform in overlying impermeable intervals, the probe could be lowered into the permeable interval to conduct the pressure survey without exposing the full length of the platform to the pressure differential forces for significant risk mitigation. The high pulling capacity of the anchoring module can be used to apply up/down force on the probe in case of differential sticking without applying high tensions to the wireline cable.

The proposed architecture for the concept platform innovatively combines several operational concepts used today as separate entities in wireline operations. Their integration, however, generates important efficiency gains, reduces the risk in stationary measurements and operations, improves accuracy, and enables the implementation of unprecedent distributed pressure measurements with azimuthal rotational capabilities using wireline. Azimuthal movements can be used to align the measurement probe away from breakouts, drilling induced fractures, debris or geological features like vugs or fractures that may compromise the sealing ability of the probe.