Laboratory Study And Field Application Of Low-cost Weak Gel

Weak gel is a certain visco-elasticity gel formed by a low concentration polymer and Crosslinking agent, weak gel is used widely and used in a large dosage in water plugging and profile control in Changqing oilfield, with the increasement of the number of wells underconstruction, the weak gel has optimized and improved constantly, and it’s performance has strengthened constantly.polymer weak gel which is linked by metal ions, like chromium ions, aluminum ions etc. can be dehydrated and breaks easily, and is with poor salt resistance and high cost, weak gel crosslinked by phenolic and resin is impacted by formation environment easily. So we developed a new kind of weak gel, aldehyde Ⅱ phenol crosslinked weak gel, which is with stability up to13months, with low cost, and is free of formation environment impact. In order to protect environment and simplify the process of compounding of Two phenolic aldehyde Crosslinked agent, aldehyde Ⅱ phenol pre-polymer crosslinking agent is developed contenting free formaldehyde for only1%, and will be tested in field in2013.The paper mainly includes the following work:Firstly, on the basis of the study on weak gel which is linked by various metal ions, and through a large number of experiments,aldehyde Ⅱ phenol is synthesis by material like polypropylene acyl amine,formaldehyde,resorcinol,Crosslinking agent additives etc. and the properties of aldehyde phenol Crosslinking weak gel is observed and studied.Secondly, for enhancing the pertinence of measurement, SWM-800-large size three-dimensional physical simulation system and two-dimensional plate models were adopted in laboratory, profile control mechanism of complicated fracture was studied in Chang4+5reservoir. Because inorganic blocking agents contains large amounts of water, this water can flow away along high permeability channel during blocking agent injecting which make inorganic blocking agents difficult to achieve effectively blocked. In order to effectively block fracture, inorganic weak gel plugging agent injection were applied, this can make full use of the advantage of each plug of plugging agent.Thirdly, in the year of2011,pro file control of14wells were constructed applying aldehyde Ⅱ phenol crosslinked weak gel in Chang4+5reservoir in Changbaishan in Changqing field.43wells of the corresponding77wells took effect,water cut decressed from71%to62.2%,daily oil production incressed from64.3t to74.2t,cumulative incremental oil was2741t,blocks natural decreasing rate decreased from17.44%to15.03%, integrated decreasing rate decreased from14.63%to10.58%,development situation improved clearly, and the recovery enhanced by2.5%.Finally, this article prospects the development of water plugging technology and profile control technology in Changqing oilfield, proposes some opinions on water plugging technology and profile control technology in Changqing oilfield.