Directional drilling in the deep gas fields of Saudi Arabia is very challenging because of the hard formations and harsh drilling conditions. The formations encountered are primarily hard limestone and dolomites interbedded with anhydrite. This paper describes various drilling solutions implemented in deep gas drilling. These solutions include:

  1. Successful introduction of open hole sidetrack (OHSDTR) technique to drill multilateral horizontal wells.

  2. Implementation of Powered Rotary Steerable System (PRSS) in Khuff and Pre-Khuff formations.

  3. Drilling Optimization to enhance drilling performance.

Conventionally, whipstock technique was employed for drilling dual laterals. Saudi Aramco and Schlumberger D&M jointly came up with the idea of drilling dual laterals using an OHSDTR technique to avoid complication due to whipstock failure. First successful dual lateral horizontal Khuff-C gas producer drilled with the open hole sidetrack technique, saved $975,000 and two weeks of rig time. It also helped in getting rid of time consuming whip stock operation which sometimes even resulted in loosing entire lateral due to unsuccessful whip stock retrieval.

With PRSS, the company was able to drill both vertical and curve sections in one run, maximize rate of penetration (ROP), and increase footage per bit run while meeting directional requirements. Successful development of the PDC bit in conjunction with the PRSS system led to record runs in all deep gas fields. Casing-to-casing sections were drilled with an improved ROP of approximately 97%, compared to that of a conventional motor. The integrated power section played a key role in improving penetration rate. In addition to tangible time savings, it offered benefits such as reduced tortuosity and better hole cleaning.

This paper reviews the design and optimization processes that when developed resulted in improved drilling performance, significantly reduced rig days and enabled early delivery of the wells in challenging deep gas drilling in Saudi Arabia.

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