| At present,waterflood is the principal method to exploit oil reservoirs in Hong Shanzui oil field which belongs to medium porosity, low permeability oil reservoir with a high clay mineral content and strong water sensitivity.in the clay mineral, with Kaolinite56.1%,with illite-smectite23%,in the illite-smectite with montmorillonite70.11%, The swelling of illite-smectite meeting with water not only leads to block pores and throats but also cause permeability reduce greatly.that injection wells are incapable to efficiently absorb water has become one of the major problems in oil and gas exploitation.current injection augmentation technics such as acidizing,fracturing and jet perforating treatmnts are disadvantageous of losing validity in short period of time,regardless of its initial effectiveness.Consequently,it is desirable to increase injection effieieney in Hong18well of Hong Shanzui oil field.people always pay attention to the injected water quality since it influence the formation properties and production performance.Good water quality is required in order to increase the water flooding efficiency and producible reserves of a reservoir, which can get the balance between the higher injectivity/productivity and lower formation damage in the heterogeneous reservoir. The injection wanter of Hong18well is analyzed and researched, The scaling and the blocking in the injection pipelines and near well bore area become more and more serious, incompatibility between injection and formation waters that one water type is Na2SO4,another is CaCl2cause scaling and block up the layer. the polymer used to control the flooding can not glue or gelling performance is poor because of high content of Ca2+.Thus, anti-scaling techniques and microbicide is important.Among many anti-scaling techniques for oil field water injection pipeline network, the chemical anti-scaling technique is still in common use at oilfields at present.HPMA is widely used with good performance,but bad stability,PHPMA that C—P and phosphatidic acid group(—PO2H2) is introduced onto HPMA not only has is good stability,but also has corrosion inhibition.Use of nanofiltration device processing water quality can effectively reduce the salinity of water and content of magnesium、calcium polyvalentions, alleviate the pressure of polymer for anti-calcium and salt calcium, prevent scaling and blocking, the polymer gel prepared by nanofiltration and ultrafiltration water which is fully compliance with the requirements of polymer flooding shows a good stability, and viscosity also greatly raised. The experimental results showed as follows:PHPMA is synthesized,when the adding concentration of PHPMA was80mg/L, anti-scaling rate of calcium carbonate、barium sulfate and calcium sulfate were100%,83.62%and94.84%,inhibiting rate was less than0.0673mm/a. NL-8Nanofiltration equipment consists of the original water tank,raw water pump, fiber ball filter, hollow fiber ultrafiltration membrane system, precise filter, metering pump dosing system, Nanofiltration host and pure water tank. Experimental research and field tests show that the membrane filter devices which consist of finefilter, ultrafiltration, nanofiltration used to treat the water of0034well for preparing polymer performs well and is of great potential for application, the finefilter could remove94.6%of suspended solids、98.7%of SRB;and ultrafiltration remove all remaining suspended solids and bacteria; nanofiltration remove32.4%of NaCl and90.54%of Ca2+、Mg2+and other divalent ions. Polymer which is prepared by using the water purified by ultrafiltration and nanofiltration fully meet the requirements of polymer flooding, whose viscos、 stability, etc. are greatly improved. On the industrial application, the effect of nanofiltration is best that polymer and crosslinking agent was reduced by13.3%and10%respectively,which not only improve the flooding effect, but also have certain economic benefits.0034well injection water was purified by NL-8nanofiltration device flooding with polymer, whose effect is good that by the end of2011.11.30, oil production increased from25t to39.and absolute cumulative oil volume had6502.63tons, water content decreased from75%to67%.Through this paper research, as a first attempt for nanofiltration device used in oil field, the advantage of nanofiltration is treating water thoroughly, and no environmental load compared to adding scale inhibitors.Nanofiltration water is main used for preparing polymer because of accurate operation and limited day processing capacity of water,PHPMA and1427quaternary ammonium salt bactericide are used in other water to stable water quality and sterilize. This research has achieved satisfactory effect in field use. |
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