A Novel Approach to Wireline Logging in Directional Wells and Difficult Logging Conditions

Abstract

Conventional wireline logging has always faced the challenge of obtaining data in highly deviated wells, horizontal wells and those with bad hole conditions. Typical solutions included pumping down tools through open end drillpipe, drillpipe conveyed wireline logging, coiled tubing conveyed wireline logging or ultimately Logging-While-Drilling.These operations are time consuming and costly. A new openhole memory logging system was introduced in 2000, initially as a more efficient alternate to pipe conveyed logging in such wells.Extensive field-testing of this system over the last few years has yielded a series of technical developments that has evolved into a low cost and unique formation evaluation logging system.This system combines memory logging with a novel deployment system that yields a cost effective approach to obtaining high quality formation evaluation data.Obtained post-drilling, the shuttle system conveys memory logging tools rapidly to TD inside the drillpipe as part of a wiper trip or check trip. Logging tools used in this system are designed to be extremely short and small diameter (2.25").The system is battery powered and includes a wide variety of capabilities including quad-combo measurements and, in the near future, repeat formation pressure testing.Logging tools are conveyed to TD inside the drillpipe.Once at TD, an electro-mechanical pressure activated release mechanism moves the tool string from inside the drillpipe into the openhole.A landing collar and latch mechanism maintains a mechanical connection between the top of the tool string and the shuttle system that remains connected to the drillpipe.A pressure signaling system not only controls the tool release but also provides simple two-way communications - a key element in providing real-time QA in the memory repeat formation pressure tester operations.Examples will be shown where these systems have demonstrated to be cost effective. INTRODUCTION The development of openhole memory logging was driven by the need to reduce total formation evaluation costs in high angle directional and horizontal wells and in wells with bad hole conditions.Also the risk of logging these wells in terms of guaranteeing data acquisition and the cost of tools lost in hole were important drivers. The choice of logging techniques in these well environments has previously been confined to LWD, pipe conveyed deployment of wireline tools and, where deviation allows, crude deployment of basic wireline tools through drillpipe.The choices made between the above options have been a compromise between cost, data integrity and value.The introduction of openhole memory logging has provided another alternative. In shallow vertical wells wireline acquisition is typically the lowest cost option, but becomes prohibitively expensive in deep directional wells due to the cost of rig time associated with pipe conveyance (bearing in mind also that LWD data is generally acquired concurrently with drilling operations).Conversely, in shallow vertical wells LWD is expensive relative to wireline tools conveyed under gravity.Memory logging occupies the middle ground. Wireline service providers have responded to the rapid growth of LWD in the past two decades by adding new measurements and more complexity.These can deliver value in many cases, but the approach is not always appropriate in mature fields that have a requirement for high quality basic measurements delivered at low cost.In this context, openhole memory logging represents a third way - neither wireline nor LWD. The memory tools' transducers, geometry and measurement dynamics are all those associated with wireline data, as are the measurements and their associated quality.They were proved initially with wireline conveyance - batteries and memory modules were added later.