Effective Mitigation of Tool Sticking Risk in Formation Testing and Fluid Sampling Operations

Prasad, Tushar (Shell) | Castillo, Homero Cesar (Baker Hughes Inc.) | Elshahawi, Hani (Shell)


The increased use of deep, highly-deviated and tortuous wells has increased the risk of wireline logging tool strings getting stuck downhole. If this risk is not appropriately managed and effectively mitigated, significant financial exposure can result from the cost of the multi-day fishing operations, the lost-in-hole and replacement charges, and -most importantly- the loss of opportunity to acquire critical subsurface data. This exposure is even higher in environments with large operating costs, such as deep water.

Historically, formation testing and fluid sampling tools have been among the most frequently stuck, fished and lost logging equipment. On the other hand, formation testing continues to provide some of the most essential information for reservoir characterization. Therefore, managing the risks associated with tool deployment is essential.

This paper discusses the sticking mechanisms of formation testing and fluid sampling tool strings, and provides specific recommendations for the planning and execution of such operations. The various factors that lead to differential sticking or keyseating of the tool string and the wireline cable are discussed. A dataset that explores a wide variety of situations is analyzed to provide a pragmatic guideline for effective mitigation of tool and cable sticking. A specific example from highly deviated deep water well is shown to highlight the significance of proactive planning.