Horizontal well StageFRAC

Tuesday, 07 February 2012 Read 3680 times
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West Siberia is the main oil production region of the company.

At the present stage of field development in West Siberia the new unconventional reserves within the low permeable Jurassic and Achimov formations are being actively developed. These reservoir targets are primarily developed by drilling a system of directional wells with further hydraulic fracture operations (HF).

 

Hydraulic fracture is critical for well completion. Without fracture operation no production enhancement could be achieved and development of low-permeable reservoir targets (JV1) will not be economic, being practically impossible for some targets at all (Ach) at the present stage of development.

With regard to technological schemes there are one-stage fracturing, selective (interval) fracturing and multiple stage fracture operation.

At one-stage fracturing all perforated zones will be affected by the injected fluid simultaneously, hydraulic fracture will be initiated at the lowest stress point and the resulted fracture height will be determined by the stress in the shale barriers. Well productivity will be dependent on properties of only one created and duly propped fracture. At multiple (selective) hydraulic fracturing of deviated wells there is a successive exposure of a formation zone or thin layer to the injected fluid provided there is sufficient number of shale barriers between zones. In this case well productivity will be higher due to stimulation of several pay-zones.

The selective hydraulic fracture is occasionally used due to high cost and high quantities of preparatory works required; its application is only possible if the borehole section revealed a favorable geological structure.

In 2010-2011 ОАО «LUKOIL» began to apply the multiple stage fracture operations in horizontal sections of wells drilled in the West Siberian fields. For the first time these operations were performed in Russia on a commercial scale. Using this technology, the propped fractures are successively created in selected zones, these zones are isolated with packers, thus only selected interval is being exposed to injection. Regarding to geological conditions, two to several dozens of hydraulic fractures could be created in one horizontal well (by the today’s worldwide statistics, the maximal number of fracs created in one horizontal well is 60).

In 2011 ОАО «LUKOIL» in collaboration with Weatherford and Schlumberger developed and successfully implemented in West Siberia the program of horizontal drilling and multiple stage fracturing. Around 100 horizontal wells have been drilled and completed using the multiple stage hydraulic fracture technology.

Comparative analysis of productivity indices of the deviated and horizontal wells with multiple stage fracture revealed a 3-5 fold increase in oil production of the drilled wells.

The results of horizontal drilling and completion operations performed in 2011 demonstrated a successful application of multistage hydraulic fracture technology for development of low permeable Jurassic formations of West Siberia.

Author

Veremko Nicholai A., Candidate of Technical Sciences.

Position
Head of the department for EOR technologies, Head Office for Oil and Gas Production and field development, OAO "LUKOIL"
Responsibilities:
Organization and coordination of activities of enterprises under OAO "LUKOIL" in the area of optimization of the oil field development, well completion technology, enhanced oil recovery and production enhancement.

Experience:
Since 1978. - A highly qualified expert in the field of oil field development and EOR. Has experience in laboratory research, pilot operations, science researches and production operation activities. More than 20 years experience in development of carbonate reservoirs; More than 12 years experience in development of clastic reservoirs.

Publications:
Supervisor of more than 42 projects of science research.
Has got more than 30 publications, including 5 inventions and a collection of articles.

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