April 24, 2011
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Home / Issue Archive / 2011 / March #3 / Analysis of Well Filter Operations – An Intake Section FVPR5(A)-12 with Compressed WMPM Filter Elements

№ 3 (March 2011)

Analysis of Well Filter Operations – An Intake Section FVPR5(A)-12 with Compressed WMPM Filter Elements

   Over 30 percent of Samaraneftegaz well stock has problems with solids entrainment. Subject to the type of solids one of the methods of ESP protection is applied: fluid filtering upstream of the pump. This method is used by plentiful oil producing companies, however for solids of specific grain size.

By I.S. Pyatov, CEO; V.V. Nikolaev, Lead Engineer; S.V. Sibiryov, Development Director, REAM-RTI A.S. Totanov, Chief Specialist of ORMF UDNG; Ya.S. Lozovoy, Chief Process Engineer, Manager of ORMF UDNG; A.A. Vasilyauskas, Chief Specialist of ORMF UDNG, Samar

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   Presence of clay, salts, asphalt-resin-paraffin deposits (ARPD) introduce essential limitations and reduce filter performance.

   In the second half of 2010, REAM jointly with Samaraneftegaz began field tests of filters series FVPR5(A)-12, designed and manufactured by REAM-RTI, which use a new type of filter elements on the basis of compressed wire mesh permeable materials (WMPM), as shown in Fig. 1.

   WMPM is a spatially-oriented wire structure manufactured by cold plastic deformation. This structure provides a “slot” effect for the flow, i.e. particles hitting the filter do not jam its pores as is the case in metallic foam structures.
FVPR5(A)-12 filters are designed with outer WMPM filter elements. Being made of corrosion-resistant wire, these filter elements provide lower flow resistance compared to conventional devices, and can operate in almost any harsh environment.

   Elastic properties of WMPM filters ensure high resistance to mechanical stress, which sets them apart from the currently used equipment, and allows regeneration of the individual filter elements for subsequent reuse.

   These advantages of WMPM allowed design engineers to make the filter element almost by 1.5-2 times shorter while maintaining the capacity; also, now the filters remain intact when equipment is taken out of a deviated well hole.
For 180 days test run were selected the following units:
three ESP type units, size 5, with filters FVPR5-12-40-200-200;
three ESP type units, size 5A, with filters FVPR5-12-S43-420-200.

   In each size one of the units had filters with bypass valves, which provide the required pumping rate in the event of filter clogging. These valves extend the servicing time of the unit.

   FVPR5(A)-12 filters were designed with module-type installation in mind, and can be joined into a filter with up to 600 cu.m/day capacity.

   Filtration rating of all filters from a pilot batch is 200 microns, which is sufficient to shrug off the proppant and its derivatives. When finer filtering is required, operators can use developed unified filter elements with filtration rating of 100 microns or less.

   Two of six pilot units are currently in operation; other two are waiting for hydrofracturing and installation.

   A test unit installed in Well 856 of Kudinovskoye field was in operation for 183 days. The inspection showed that the unit went down because of a filter shaft failure due to emergency operation mode of the ESP (propping). Only 15-20 percent of the filter element surface was covered with solids; this means that in normal operational mode the ESP unit would run for approximately 900 hours. After the inspection it was decided to reinforce the shaft of FVPR5(A)-12 filter for pumps of capacity over 100 kW; for such models a special shaft version (22 mm instead of 17 mm) was designed.

   The unit in Well 714 of Kudinovskoye field was pulled out for geological and technical maintenance (GTM) after 92 days of operation. Unit disassembly revealed partial clogging of filter elements with asphalt-resin-paraffin deposits. It should be noted that no flow rate decrease or extremely high frequency growth was reported during its operation (Fig. 2).

   In both cases, the working body of the pump has slight wear of washers and bushings. There are no solids, proppant or its fragments in the inner cavities of the filter and pump, which confirms the high efficiency of WMPM filters for the ESP unit protection after fracturing works.

   Available preliminary test results allowed further design modernization: a frame for filter elements has been reinforced; wingtips of filter elements have been replaced (to provide better corrosion resistance); engineers designed a new modification of FVPR5(A)-12 filter with the reinforced shaft.
Conclusions and Recommendations

   The outcomes of field testing of the filters with WMPM filter elements manufactured by REAM-RTI verify that this type of filter elements is highly effective, when used for ESP unit protection in wells with heterogeneous solids, scaling and asphalt-resin-paraffin deposition due to design features and low hydraulic resistance.

   REAM’s WMPM filter elements demonstrated high capability of efficient regeneration and reuse in filtering systems of downhole equipment.
It is recommended to test a larger quantity of FVPR5 and FVPR5(A) filters fitted with bypass plate valves to verify their efficiency to increase ESP units performance in wells with solids of heterogeneous composition.

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