Production enhancement from sand management philosophy. A Case Study from Statfjord and Gullfaks
- Jamie Stuart Andrews (Statoil) | H. Kjorholt | H. Joranson
- Document ID
- Society of Petroleum Engineers
- SPE European Formation Damage Conference, 25-27 May, Sheveningen, The Netherlands
- Publication Date
- Document Type
- Conference Paper
- 2005. Society of Petroleum Engineers
- 3 Production and Well Operations, 4.1.9 Tanks and storage systems, 4.3.4 Scale, 1.6 Drilling Operations, 4.1.2 Separation and Treating, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 4.2 Pipelines, Flowlines and Risers, 5.1.1 Exploration, Development, Structural Geology, 1.8 Formation Damage, 1.2.3 Rock properties, 5.6.4 Drillstem/Well Testing, 3.2.5 Produced Sand / Solids Management and Control, 4.1.5 Processing Equipment, 2.4.3 Sand/Solids Control, 4.5 Offshore Facilities and Subsea Systems, 2.2.2 Perforating, 4.2.3 Materials and Corrosion, 2.4.5 Gravel pack design & evaluation
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Statfjord and Gullfaks are "Brown" fields operated by Statoil in the Tampen area of the North Sea. The production from these fields is characterized by large volumes of water and increasing sanding tendencies. The operator has for many years followed a strategy whereby sand produced with the wellstreams has been handled topsides prior to on-site disposal. The adoption of a sand management strategy has been crucial for prolonging economic reservoir development during tail production.By choosing to deal with sand topsides the operator has been able to pursue low cost slot replacement drilling where wells are completed without sand control equipment. The cased-hole functionality has facilitated multi-target drilling and is suited to selective production of each sand member through cheap plug/perf interventions.
Significant gains in production (acceleration) and reserves (IOR) have resulted from the pursuance of sand management in these fields.Examples of wells showing productivity improvements as a direct result of allowing intervals to produce sand are presented. In addition, production gains achieved from replacing choked back "sand free" production with "maximum acceptable sand rate" production are presented. Increased sand tolerance has also led to reserve increases in some wells as unproductive intervals that were previously sanded up have cleaned up and started to flow. It will be argued that this strategy negates many concerns with formation damage during well work because such damage is produced out with the sand and the wells clean up naturally.
The transient nature of sand production is discussed and the production gains observed in each field is presented.Such a strategy requires that the sand production is managed in a safe and controlled manner where the negative consequences of sand production are manageable and predictable. This paper will also discuss the improvements made in sand detection and on-line erosion mapping required to improve the sand tolerance of these facilities.
Sand management is not a new concept. It has been used successfully in heavy oil developments for several years. Cold production of oils with viscosities as high as 11000 cp has found to be economic provided large sand influx is maintained in these wells. Erosion concerns in such low velocity cases are generally not limiting. In more traditional environments, sand production has been considered unacceptable. Operators have typically implemented a conservative approach where production rate (and revenue) has been restricted to reduce sand production and decrease the risk of erosion leading to a loss of containment. However, recent sand management practices have shown good results in both technical and economic terms through controlled sand production to surface rather than classical sand control through total sand exclusion[2-5].
On Statoil's Statfjord and Gullfaks fields a sand management strategy has been in place for more than a decade. By choosing to permit sand production to surface the operator has reaped production benefits and avoided costly sand control completions during infill drilling operations. This strategy has moved the production bottleneck away from well potential and over to sanding levels on these fields. Typically, wells are choked back to a maximum sand free rate (MSFR) or to a Maximum Acceptable Sand Rate (MASR). Production of sand creates disposal issues and several integrity challenges:
Sand is erosive and may affect the functionality of valves and regularity equipment.
Uncontrolled erosion can lead to loss of integrity and hazardous situations.
Sand fill in separators or storage tanks /transportation vessel may cause process problems and ultimately lead to costly shut downs and removal operations.
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