Synthesis Research And Performance Evaluation Of Anti-scaling Agent For Coalbed Methane Squeeze Injection

In recent years,we have strengthened the efforts to developing coalbed methane in our country,scaling is one of problems we encountered in the development,scaling problem can not only negatively affect the production of CBM,but also cause environmental pollution problems at some level.At present,squeezing inhibitor treatment technology is widely used in oil field at home and abroad because it has special advantages of long-term life and wide scope compared with other traditional scale inhibition methods,but it's rarely used in coalbed methane development scaling in the report.Therefore,the squeezed scale inhibitor is researched for coalbed gas reservoir and low permeability and the hydrophobic and lipophilic characteristics of Junlian shallow CBM blocks,which is based on field scaling survey.Ultimately,the research determines the optimum synthesis conditions of it,analyzed the structure of it,and evaluates its the anti-scaling,compatibility and adsorption properties.The research analyzes the field scale investigation and scaling trend of Junlian shallow CBM block,the results shows that scaling mainly occurred in the wellbore,main component of scale sample is calcium carbonate based inorganic salt and iron oxide and iron sulfide based on corrosion products,the water type of gas block produced water is sodium bicarbonate,salinity and scale-forming ions concentration of gas block produced water is high.The reasons of scaling is related with water quality,temperature and pressure,pH,pipe quality and water production and so on.The results showes that most of the block SI>0 by using SSP2010 scaling prediction software,there is a serious calcium carbonate scaling tendency.A squeezed scale inhibitor(LPB)takes acrylic acid(AA),butyl acrylate(BA)and sodium hypophosphite as raw material to synthesize ternary copolymerization by solution polymerization.Through its anti fouling effect evaluation to the research determines the optimum synthesis conditions:w(BA/AA)= 5%,w(NaH2PO2)=3%,w((NH4)2S2O8)=1.4%,reaction temperature is 75 ?,reaction time is 5h.The chemical structure of LPB is identified by IR and 1H-NMR.According to reservoir conditions of junlian shallow CBM blocks,the research discusses the antifouling performance of LPB in terms of dosage,temperature,pH,etc.The results showes that:when the temperature is 45 ?,MIC values of LPB is 20mg L,that antiscaling efficiency value reachs 91.51%;the antiscaling efficiency of LPB decreases with increasing temperature in the temperature range of the block;LPB showes good antifouling performance in the range of 7 to 8 of the block produced water pH value;LPB is compatible with gas produced in the use of a range of concentrations.The research analyzes the antiscaling mechanism of LPB in the terms of chelation adsorption,coagulation dispersion and lattice distortion combined with scanning electron microscopy.By compared with Phosphonate group with the sodium polyacrylate(PAAS),the research evaluates adsorptive retention of LPB on coal rock in terms of static surface adsorption retention and dynamic adsorption retention and analyzes the scale inhibitor concentration,temperature,chloride content,displacement speed and other factors.The results indicates that:static surface adsorption of LPB and PAAS on coal rock corresponded to the Langmuir law,the adsorption capacity of LPB is greater than PAAS;the adsorption capacity of LPB and PAAS decreases with increasing temperature;the adsorption capacity of LPB and PAAS increases with exaggerating sodium chloride content,but does not increase when they have reached saturation adsorption;the squeezing life of LPB on coal rock is 1.73 times the PAAS under the same conditions;the squeezing life of LPB on coal rock increases limitly with exaggerating the concentration of the initial injection;the larger water production of gas wells,the shorter the squeezing life of LPB.LPB is the squeezing scale inhibitor applying to CBM,while introducing a hydrophobic group and a phosphine group comparing with conventional sodium polyacrylate scale inhibitor(PAAS).LPB has not only excellent antifouling effect and longer squeeze life easy to monitor,but also easy to monitor,should be able to extend the pump inspection time and reduce the cost of mining,has some Guiding significance in the future development of coalbed methane squeezing scale inhibitors.