This paper reviews the recently concluded first Near-Balanced Nitrified Stiff Foam application for a fractured low pressure reservoir formation; Sui Main Limestone in the Baluchistan region of Pakistan. The SML formation has presented extreme drilling challenges in this field. Severe loss circulation and reservoir influxes have made drilling this formation a night mare for the operator. Lot of Non Productive time has been spent while trying to pass through this formation. A recent application of the unconventional and innovative technologies has provided the client with an excellent solution. The major scope of work for this well is to pass the SML formation without having loss circulation and reservoir influx into the well bore while keeping good drilling performance and finally case the complete formation in one casing.

A brief history of the Near-Balanced Drilling Technology using the Nitrified Stiff Foam fluid is provided in this paper which is followed by a discussion of the remarkable results achieved in this well. While performing the job the loss circulation problem was totally eliminated. Near-Balanced condition was constantly being monitored and maintained throughout the operation that resulted in no inflow from the reservoir into the well bore. Stiff Foam application also resulted in gaining outstanding drilling performance. All this resulted in the drilling of this formation in time less than half of the planned days. Finally the complete formation was cased within one casing without any complication.

In Summary; application of the state-of-the-art and advanced technologies helped operator to eliminate the NPT associated with the drilling of this challenging formation. The operator was not only benefited with the rewards of this application but it also helped it to perform the Post Drilling operations in controlled, safe and desired manner. This paper reviews the process that was used to identify, plan, and implement these unconventional techniques. The purpose of this paper is to highlight all the benefits and lessons learnt while performing this first Nitrified Stiff Foam Near-Balanced Drilling mode application in Pakistan. This will help many operators in the designing and implementation of such techniques to challenging hydrocarbon bearing formations.

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