Stuck-Pipe Prevention Solutions in Deep Gas Drilling; New Approaches
- Julio M. Guzman (Saudi Aramco) | Mohamed E. Khalil (Saudi Aramco) | Nicolas Orban (Schlumberger) | Mohammed Ahmed Mohiuddin (Schlumberger) | Jaywant Verma (Schlumberger) | Sukesh Ganda (Schlumberger)
- Document ID
- Society of Petroleum Engineers
- SPE Saudi Arabia Section Technical Symposium and Exhibition, 8-11 April, Al-Khobar, Saudi Arabia
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 1.6.7 Geosteering / Reservoir Navigation, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 1.6.2 Technical Limit Drilling, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 1.6.1 Drilling Operation Management, 5.8.7 Carbonate Reservoir, 1.2.3 Rock properties, 1.6 Drilling Operations, 1.7.5 Well Control, 1.6.6 Directional Drilling, 4.1.5 Processing Equipment, 1.12.2 Logging While Drilling, 4.1.2 Separation and Treating, 1.2.2 Geomechanics, 2.5.4 Multistage Fracturing,
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The primary cause of nonproductive time (NPT) incurred by Saudi Aramco in the deep gas drilling environment is stuck-pipe incidents. These incidents are mostly caused by hole cleaning, differential sticking, and wellbore stability issues.
To address the stuck-pipe incidents, the Saudi Aramco drilling engineering division and a service company together developed new procedures and techniques that proved to be efficient in stuck-pipe reduction.
Poor hole cleaning was identified as the main reason for stuck-pipe incidents. Procedures with compilation of best practices having reference to planning, drilling, tripping, and working tight spots were introduced. Torque & drag (T&D) simulation, along with equivalent circulating density (ECD) monitoring, was introduced as a road map to give a bigger picture and to give warning signs along the way.
In addition, past experiences showed that mud weight could significantly be reduced without gas flow occurring. This highlighted that, due to the complex nature of the reservoir, uncertainty existed in reservoir pressure estimation. Hence, it was recommended to run a formation-pressure-while-drilling service to better understand the formation pressure distribution. The idea was to measure, while drilling, the formation pressure of different layers, which would allow an optimal overbalance adjustment to mitigate the differential sticking risk.
Even though drilling in the direction of minimum horizontal stress leads to maximizing the propagation of fractures during the stimulation phase hence increasing production rates, it has also been observed that it leads to wellbore instability, which in turn causes stuck-pipe incidents. To address the stuck pipes in such situations, a technique was developed based on creation of mechanical earth models (MEM). This practice has helped to interpret the response of the wellbore by identifying hazards and to raise awareness of wellbore stability.
The services have been an innovative approach to mitigation of stuck-pipe incidents in deep gas drilling. The techniques are a way forward to reduce stuck-pipe incidents and hence lost-in-hole situations.
The primary cause of nonproductive time (NPT) incurred by Saudi Aramco in the depleted deep gas drilling environment of the giant Ghawar carbonate field is stuck-pipe incidents.
The Ghawar oil field is by far the largest conventional oil field in the world and accounts for more than half of the cumulative oil production of Saudi Arabia. Although it is a single field, it is divided into six areas.
The Ghawar field was discovered in 1948. Production began in 1951 and reached a peak in 1981. This is the highest sustained oil production rate achieved by any single oil field in world history. Gas drilling was initiated in 1987. Gas wells are mainly drilled in the south portion of the field in late Permian KB and KC stacked carbonate reservoirs at depths of 11,500 ft to 12,000 ft true vertical depth (TVD).
In a typical gas well, kickoff is at approximately 9,500 to 10,000 ft TVD in base of the Jilh dolomite; the well profile requires 3.5 to 4° build rates to land in K-C carbonate. Next, casing is planned and set at about 70° inclination. A pilot hole of approximately 2,000 to 3000 ft in length is then drilled across twelve K-C layers. Based on the porosity results of the pilot hole, a specific K-C layer is targeted for another 5,000-ft lateral.
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