Accepting the Challenges of Hostile Well Conditions in Onshore Wells-a Case Study
Manoj K. Tewari, Jaipal Singh, and Ramachandra Rao Doddapaneni
WLS, ONGC, Nazira, India
The hostile condition for logging put forth a challenge for logging data acquisition. The conventional Tough logging conditions (Tool Pusher technique) provided an escape route to logging data acquisition for formation evolution. Hostile conditions can arise due to many factors. One of the outcome of such conditions can be non- conveyance of logging devises to the desired depth resulting in no open hole data acquisition. There are many instances that even in vertical wells the conveyance of tools has become a problem and well log data acquisition could not be made possible.
The remedial measures are either convey the logging devices by drill pipes or log the well while drilling with logging devices put in bottom hole assembly and transfer the signal by mud pulse telemetry or evaluate the wells with cased hole formation evaluation techniques.
The Tool Pusher Technique gives a better scope for running the all logging services from conventional to high tech with better precision after the well is drilled to the desired depth and log parameters are to be corrected for borehole conditions.
Mud pulse telemetry system is less time consuming particularly in exploratory wells as the information received is not influenced by mud filtrate invasion; but in the less potential wells the cost of logging may prove to be capital intensive and lost equipment situation in hostile well may be pinching. With the advancement in the mud chemistry this problem claimed to be addressed?
Another way out is to record the logs when well is cased. The industry presents a series of logging equipments for formation evaluation in cased hole. This is not the best solution always for data acquisition depends upon the merit, objectives and category type of drilled wells.
Present paper is a case study of few wells where all these techniques are used and comparison logs are discussed. It will add value towards the planning of well logging jobs. Of course, it is the client, who has to take the decision which one is best suited to meet his requirements.
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