26 Inch Hole Sidetracking Problems in Salman Oil Field, Persian Gulf: A Case Study
- Amir Masoud Kalantari-Dahaghi (Petroleum U. of Tech Iran) | Abolghasem Rahchamani (Petroiran Development Co) | Jamshid Moghadasi (Petroleum U. of Tech Iran) | Vida Gholami (Petroleum U. of Tech Iran)
- Document ID
- Society of Petroleum Engineers
- International Oil & Gas Conference and Exhibition in China, 5-7 December, Beijing, China
- Publication Date
- Document Type
- Conference Paper
- 2006. Society of Petroleum Engineers
- 1.14 Casing and Cementing, 4.2 Pipelines, Flowlines and Risers, 1.6.1 Drilling Operation Management, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.6 Drilling Operations, 1.6.9 Coring, Fishing, 1.6.11 Plugging and Abandonment, 4.6 Natural Gas
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This paper describes the reason of sidetracking in 26 inch hole of Salman field in Persian Gulf, its problems and restrictions including unconsolidated formation type, existence of washout below the conductor pipe, probability of anti collision , limitation to survey in order to determine the well situation and short side track interval. Finally the methods for overcoming these problems in order to do a successful sidetrack are explained.
The Salman Oil and Gas Field is an active oil producing complex in the Persian Gulf, in Iranian waters some 144 km south of Lavan Island. This field straddles the Iran - Abu Dhabi border with approximately two-thirds of the producing structure lying in Iranian waters. Water depth in the Salman field ranges between 20.0 and 43.3 metres, when measured at lowest astronomical tide (LAT).
The existing off-shore facilities at the Salman oil and gas field has been producing since 1968 and its current production rate is 100,000 bbl/day. The extracted crude oil is processed and exported via a sub-sea pipeline to onshore facilities at Lavan Island.
The oil is extracted from satellite platforms connected via a network of sub-sea lines to a central platform complex from where it is piped to shore.
The Salman Offshore Facilities Project involves enhancement of crude oil production by some 50,000 bbl/day and will incorporate new gas production facilities capable of processing 500 MMSCFD (dry basis) of gas from Dalan and 40 MMSCFD (dry basis) of Salman associated gas.
The Salman well 2SKB-2, as the third deviated gas development well on "B?? platform, (Fig 1), is one of the 9 gas wells commitment to be drilled in Salman buy back project.
This well is the 7th deviated development Kangan / Dalan gas well which to be drilled as a deviated well to the northeast with the general azimuth of ± 42º.The horizontal displacement of the well from platform to the northeast at the top of Kangan reservoir and the total depth is 1500m and 1700m respectively.
While milling the collapsed 30??conductor pipe, a 17 ½?? Taper mill was left in hole (TOF at 153.8m).
Several trips done to recover fish without any success, finally the engineering team went through two choices: Abandon the well or Sidetracking.
Well abandonment was really easy but PEDCO engineering team chose the difficult case.
Some factors while doing this rare job made it somewhat impossible which are classified as below:
- Unconsolidated Formation & wash out
- Anti-collision risk
- Short Sidetracking interval
- Surveying limitation
Unconsolidated Formation & washout
The Quaternary sequence consists of recent sandstones and unconsolidated lime mud which makes the shallow formation below sea bed in Salman field consists of chalky and marly bioclastic and coquina limestone. Beds of gypsum and anhydrite towards the base are also present. The main characteristic of this sequence is poor cementation between rock solids and grains as a result, wash out of this unconsolidated group by high flow rate which is standard for drilling 26"hole (1000 GPM) is reasonable.
As mentioned above well 2SKB-2 was the third well on "B?? platform, so sidetracking this wellbore to a direction far from other wells and especially from Iran-UAE boarder made this job critical. An anti-collision program ran and the best plan extracted and programmed.
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