SVIBOR - Project code: 2-01-135


Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69


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Project code: 2-01-135

Formation Damage Caused by Borehole Fluids

Main researcher: STEINER, IVO (44756)

Type of research: basic
Duration from: 01/01/91. to 12/31/95.

Papers on project (total): 75
Papers on project quoted in Current Contents: 3
Institution name: Rudarsko geološko naftni fakultet, Zagreb (195)
Department/Institute: Mining, Geotechnics and Petroleum Engineering Department Petroleum Engineering Institute
Address: Pierottijeva 6, 41000 Zagreb
City: 10000 - Zagreb, Croatia
Phone: 385 (041) 440406
Fax: 385 (0)440008

Summary: Production of hydrocarbon fluids (oil and gas) and water through wells is dependent on condition of inflow of such fluids through the zone surrounding those wells. Formation damage in this zone is a consequence of pressure of the fluid filling the well during its drilling, completion and workover. Conditions were studied in whose damage of the zone surrounding wells originates and how this damage can be prevented or how consequences of it can be eliminated or decreased. By study of relevant literature, by analysis of production parameters and by laboratory tests which simulate in situ conditions in rocks there was an attempt to find solutions to improve production conditions of valuable mineral fluids. Laboratory equipment, between which own designs were too, have been used for simulation of processes in pay zones and in wells. From literature recepies for well killing fluids were found which do not damage or minimally damage rocks along the wellbore. Purposeful application of horizontal and extended-reach wells, which enable more convenient conditions for fluid inflow into wellbore, is suggested. Prevention of corrosion products and chemical percipitates, which can cause formation damage, were studied too. In the years 1994 and 1995 research on influence of technology on prevention of formation damage has been continued. Primarilly it was done by application of deviated, extended-reach and horizontal wellbore, as well as by improvement of borehole stability. Improved was the application of X-ray Computerized Tomography in study of fluid flow through cores.

Keywords: formation damage, chemical formation damage, mechanical formation damage, killingof the well, horizontal well, chemical percipitate, corrosion products, mineral fluid production, X-ray Computerized Tomography

Research goals: Fundamental goal of research of the influence of borehole fluids (drilling fluid, salt water and other fluids in wellbores) on formation damage reduction of productive sandstones and other oil, gas and water bearing rocks is the improvement of the quality of operations in drilling, in well casing landing and cementing practice, in completion and workover of wells as well as in production of commercially valuable fluids with reduced costs per volume unit of those fluids. Expected results are: 1. Recepies of borehole fluids causing lower formation damage; 2. Design of three-dimensional nozzles for drillin bits which for identical cleaning efficiency as applied ones with circular openings require lower jet velocity and lower pressure of circulating fluid on rocks at the hole bottom; 3. Programming of drilling of extended-reach and horizontal wells in selected fluid deposits in an aim to achieve conditions for more favorable influx of valuable fluids into wellbores.


  1. Name of project: 2-01-135 Smanjenje propusnosti stijena bušotinskim fluidima
    Name of institution: Rudarsko-geološko-naftni fakultet Sveucilišta
    City: 10000 - Zagreb, Croatia

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Last update: 10/12/95