Managed Pressure Drilling, the Impact of Correctly Applying the Technology and the Results Obtained After Drilling an Exploratory Well in a Deep Gas Reservoir of Saudi Arabia
Authors: Al-Thuwaini J.. , Emad M.. , Ketabchi I.. , Torres F.. , Russell R.. , Arnone M.. 
Published: January 2010

Saudi Arabia has at today a reported fourth largest reserve of Natural gas in the world and as the fastest growing energy consume in the Middle East it is also consuming the totality of the national gas production, having no net import or exports of Natural Gas. The Natural Gas production and consumption was increased by 62% in the last 10 years and the demand in the country is expected to double the actual capability by 2030. This is the proposed target, and it is expected to be achieved under significant investment of foreign companies that are planning and executing projects related with non-associated gas fields in different areas of Saudi Arabia.

Several oil companies are focused in explore, and produce in case of success exploration campaign, from high pressure, high temperature and deep gas reservoirs. The grade of reservoir properties anisotropy including the high uncertainty of pore and fracture pressures in the hostile environment that a conventional drilling practice will face in the deep exploratory wells is not resulting at the end as an efficient and viable way to reach the planned production target.

The correct application of a new technology as Managed Pressure Drilling (MPD) has demonstrated the impact in the successful result obtained specifically in Saudi Arabia. This paper is summarizing the planning process behind an MPD project as well as the description of the obtained results in a case history.

In the exploratory well project case developed in this paper, the main driver for MPD was to reduce the Non Productive Time usually experienced in other exploratory off-set wells drilled in the same basin by ascertaining in real time the reservoir pressure limits (pore and fracture) controlling mud losses and influx events associated with the new formation drilled. The right determination of the pressure balance between fluid losses and influxes was achieved and the operational window was successfully managed during all the stages of the MPD operation.

Traditionally, the high solids content of the drilling fluid used in conventional drilling practices in this area, which main objective is to obtain an extreme overbalanced condition that could overlap the high level of reservoir uncertainties and anisotropy, is also damaging the reservoir itself, impacting the final production and productive life of the well. The content of solids was reduced to the minimum during this MPD operation, managing the annular pressure just by manipulating the MPD equipment adjusting in real time the back pressure exerted from surface.

MPD reduced at the minimum the drilling non productive time associated with common hazards usually observed during conventional drilling practices in the same area and also finalized the exploratory well drilled in this deep gas reservoir without report any incident. In addition it has improved the reservoir production compared to the wells that were drilled conventionally.