Patent EA-005253-B1 (EA)
Title: Arrangement for and method for restricting the inflow of formation water to a well
IPC: E21B43/12
Filed: 2002-04-26
Abstract: 1. An arrangement for restricting the inflow of formation water from an underground formation to a hydrocarbon producing well, where, between the underground formation and a production tubing (38) located in the well, there is disposed at least one flow chamber (3,33) connected to the production tubing (38), the flow chamber (3,33), preferably via a filter (2) in one portion, being open to inflow of formation fluid and in communication with the production tubing (38) via at least one opening (7, 32), characterised in that the flow chamber (3,33) is provided with at least one free floating body (4,34) with approximately the same density as the formation water, where the at least one body (4,34) is designed through the closing of at least one opening (32) or choking, to reduce the inflow of formation water to the production tubing (38). 2. An arrangement in accordance with claim 1, characterised in that several bodies (4) are arranged in the flow chamber (3), which bodies through aggregation to a packed form (14) are designed by means of buoyancy and gravitational forces to choke the flow of formation water through the flow chamber (3). 3. An arrangement in accordance with one or more of the preceding claims, characterised in that a plug (39) is disposed between the flow chamber (33) and the interior space of the production tubing (38), which plug projects into the production tubing (38), and where the plug (39) is provided with a non-through bore extending from the flow chamber (33) to a position on the inside of the pipe wall of the production tubing (38), the inwardly projecting end portion of the plug (39) being designed to be removed by means of a well intervention tool or liquid solvent, whereby the bore of the plug (39) is opened to flow. 4. An arrangement in accordance with one or more of the preceding claims, characterised in the production tubing (38), outside the part of the flow chamber (33) in which the free-floating bodies (34) are disposed, being provided with through openings (31). 5. A method of restricting the inflow of produced formation water from an underground formation to a hydrocarbon producing well, where, between the underground formation and a production tubing (38) located in the well, there is disposed at least one flow chamber (3,33) connected to the production tubing (38), the flow chamber (3,33), preferably via a filter (2) in one portion, being open to inflow of formation fluid and in communication with the production tubing (38) via at least one opening (7,32), and where the produced hydrocarbons have a density that is different from the density of the formation water, characterised in that during flow of the produced hydrocarbons through the flow chamber (33) bodies (34) with approximately the same density as the produced formation water are kept, through gravitational and buoyancy effects, substantially away from openings (32) provided between the flow chamber (33) and the interior space of the production tubing (38), the similar densities of the bodies (34) and the formation water causing the bodies (34), as the formation water flows through the flow chamber (33), to be whirled around in the formation water that completely or partially fills the flow chamber (33), whereby they may cover the openings (32) and by so doing, gradually reduce the flow rate of formation water from the flow chamber (33) to the production tubing (38), alternatively they may concentrate to form an aggregate (14) in the flow chamber (3,33), which reduces the flow rate of formation water.