the resins tested are defined hereafter by their trade name or number belonging to the borden company , as well as by their composition given by the maker , completed by other measurements . these are phenolic resins , preferably phenol - formol resins , in particular resol type phenol - formaldehyde resins . the residual water content of the solid resins is determined by differential thermal analysis tga . the amount of water in the initial product is measured by means of the karl fischer method or by azeotropic distillation . similarly , the free phenol and furfuryl alcohol concentrations are determined after chloroform extraction and chromatographic separation . table 1______________________________________ borden bordenresins 5002 5004______________________________________viscosity at 25 ° c . ( pa . s ) 0 . 07 0 . 021density at 20 ° c . 1 . 19 1 . 16ph at 20 ° c . 7 . 95 8 . 70dry matter after 2 hat 150 ° c . 62 % 38 % at 250 ° c . by tga 36 % 62 % water content % ( value 17 % 9 % provided ) karl - fischer test 19 - 23 % 12 % free phenol content -- -- tga extraction test 5 . 3 % 4 . 7 % furfuryl alcohol content -- 38 % chromatographicdetermination______________________________________ a resin 5005 ( borden ) which notably differs from resin 5004 in a furfuryl alcohol content of about 50 % is also tested . a rayneri paddle agitator has been used to prepare the formulations . with this type of device , the agitating speed was set to 500 rpm for about 30 minutes . for formulations containing mineral fillers , agitation was performed with a waring mixer for 5 minutes . the setting time of resins is determined according to the thickening time determination technique . the thickening time is determined with a consistometer according to a procedure defined by the petroleum cementing standards api 10 . this device mainly consists of a cylindrical vessel containing the material , equipped with a stationary agitator paddle . this assembly is dipped in a pressurized thermostat - controlled cell . the rotating speed of the bowl is 150 rpm , the agitator is secured to a calibrated spring and to a potentiometer allowing to measure the torque exerted on the paddle by the cement . the spring is periodically calibrated with a weight calibration equipment . the end of the test is determined by the torque measurement . as soon as it is prepared , the formulation is set in the cylindrical vessel . the latter is closed by a flexible diaphragm which isolates the resin from the pressurization oil while transmitting the pressure . after applying an initial pressure , heating is started with a predetermined warm - up rate . the pressure is readjusted , at the end of the warm - up time , to the value required for the test . measurement of the thickening time ends when the torque reaches the limit set during calibration . it is the time passed since heating has been started which determines the thickening time . a haake viscometer associated with a thermostat - controlled cell is used . the working principle of this device is based on the &# 34 ; single air gap &# 34 ; or &# 34 ; double air gap coaxial cylinders &# 34 ; configuration . the fluid to be studied is placed in the stator , the internal cylinder being connected to the rotor . the internal and external cylinders are provided with grooves in the direction of the generating lines in order to prevent slippage on the wall . the rotating speed and the torque measurement are achieved on the shaft of the rotor . the velocity gradient or deformation rate on the wall of the internal cylinder is linked with the rotating speed of the rotor . the tangential stress on the wall is linked with the moment of resistance measured on the shaft of the rotor . the flow law relating the stress τ ( pa ) to the shear rate γ ( s - 1 ) is associated with a mathematical model . examples of the commonest models are : ostwald model : τ = kγ n with the consistency index and n the fluid behaviour index bingham model : τ = τ o + μγ with μ the plastic viscosity and τ o the threshold stress . setting of the resins is performed in 7 - cm high molds having an inside diameter of 2 . 5 cm . prior to pouring the resin , the molds are previously coated with grease and silicone . after filling with the selected resin , the molds are placed in a setting cell under temperature and pressure conditions . the samples are thereafter redimensioned and characterized , notably by measurement of the compressive strength and of the permeability . the testing device comprises a stationary lower plate and an upper plate to mounted on a knuckle joint . the compression stress is applied until the cylindrical sample of section s breaks . the maximum applied load f is measured by means of the device . the compressive strength is defined by the relation : r c = f / s . r c is expressed in pascal , f in newton and the surface area s in m 2 . the permeability constant k is evaluated from the injection of water into a resin sample subjected to a confining pressure of 40 bars . the system is laterally sealed by interposing a cylindrical membrane on the walls of the sample . the amount of water that has flowed off is measured alter several hours . the calculating formula used is as follows : ## equ1 ## with : μ the viscosity of the fluid in pa . s , k in m 2 ( 1 m darcy = 0 . 987 10 - 15 m 2 ). the setting time is measured as a function of the effect of the temperature in order to determine if , as it is , the resin on which the cementing composition is based is compatible with the setting time requirements which commonly prevail in the trade . the required setting times are generally of the order of 3 to 5 hours according to the depth of the cementing operation . the results are shown in table 2 . the setting times of the resins are assessed in relation to the thickening time as defined above . table 2______________________________________thickening timetemperature (° c .) borden 5002 borden 5004 borden 5005______________________________________ 80 9 hours & gt ; 48 hours & gt ; 48 hours100 2 hours & gt ; 48 hours & gt ; 48 hours120 55 minutes 8 . 33 hours & gt ; 48 hours140 & lt ; 30 minutes 3 hours 5 hours______________________________________ furfuryl alcohol modified resins have setting times compatible with their use as a component of a cementing material . it can be noted that varying the proportion of furfuryl alcohol allows to readily control the setting time , considering the temperature used . fig1 shows curves giving the setting time , laid off as ordinate , as a function of the temperature , laid off as abscissa , for resin 5002 ( reference number 1 ), resin 5004 with 78 % by weight of caco 3 and 50 % by weight of silica sio 2 ( reference number 2 ) and resin 5005 also with a caco 3 and sand filler ( reference number 3 ). it can be noted that the type of unreactive filler has practically no influence on the setting time . fig2 illustrates the theological behaviour of the resin borden 5004 , with or without filler , at 90 ° c . the rheogram gives the shear γ ( s - 1 ), laid off as abscissa , and the corresponding stress rate τ ( pa ), laid off as ordinate . the pure resin 5004 shown by curve 4 , at the test temperature ( 90 ° c . ), shows that the stress rate cannot be measured in the shear range studied : from 10 to 100 s - 1 . at this temperature , the resins become very fluid in relation to conventional cement slurries . curve 5 relates to resin 5004 to which 33 % by weight of a caco 3 filler has been added . an ostwald type rheological behaviour appears when adding a certain amount of filler . furthermore , it has been measured that the viscosity of a resin can be readily controlled according to the grain size of the filler . for the same percentage by mass , the silica smoke filler of small grain size has a greater influence on the viscosity than a filler of larger grain size such as caco 3 . fig3 shows examples of rheograms of the resin 5004 containing fillers of different natures and concentrations . measurements have been performed at 90 ° c . curve 6 relates to a mixture containing 33 % caco 3 . curve 7 relates to a mixture containing 50 % caco 3 . curve 9 relates to a mixture containing 78 % caco 3 . table 3______________________________________type of filler silica sio . sub . 2 silica smoke caco . sub . 3 microsilica______________________________________average grain size 50 2 5 0 . 012 ( μm ) ______________________________________ influence of the nature of the filler on the thickening time of resin borden 5004 : table 4______________________________________temperature 5004 + 78 % caco . sub . 3 +(° c .) 5004 50 % sio . sub . 2 5004 + 25 % sio . sub . 2______________________________________120 8 h 20 9 h 10140 3 h 00 2 h 50 3 h 10160 1 h 00 1 h 15 1 h 05______________________________________ the setting time of resin 5004 is little sensitive to the amount of filler and to the nature of the unreactive filler . the influence of fillers on the mechanical properties of the resins has been studied by measuring the compressive strength . the effects of the fillers is observed on the resin 5002 set at 80 ° c . after 3 days . all the measurements are summed up in table 5 . like the viscosity , the compressive strength generally increases with the amount of particles added . furthermore , all the compressive strength values are markedly greater than those corresponding to a conventional cement slurry formulation which is of the order of 30 to 50 mpa . table 5______________________________________measurement of the compressive strength r . sub . c ( mpa ) resin borden 5002 + filler % of filler 0 0 . 5 1 2 5 10 15 20 25______________________________________silica smoke 60 68 80 57 58caco . sub . 3 60 62 75 80 60microsilica 60 70 97 81______________________________________ in particular , the resistance effect is the most notable for the microsilica which has the finest grain size . in fact , filling of the organic matrix is much denser with fine particles , which accounts for the compressive strength increase . in order to try to increase the compressive strength value , mixtures of fillers whose proportions are determined by optimizing the dry compactness of the mixture can be used . the filler formulations defined in table 6 could be advantageously used . table 6______________________________________filler formulationsformulation no . 1 no . 2 no . 3______________________________________composition 10 % silica 10 % silica 5 % silica smoke smoke smoke 15 % caco . sub . 3 10 % caco . sub . 3 12 . 5 % caco . sub . 3 20 % silica 10 % silica 12 . 5 % silicacompressive 94 98 96strength r . sub . c withresin 5002 at 80 ° c . ______________________________________ it can be seen that optimization of the mixture of fillers leads to improved compressive strength values . relation between the permeability ( k ), the speed of sound ( v ) in the material and the compressive strength ( r c ) various techniques have been used in order to establish the effect of mineral fillers on a series of mechanical properties . the results of the measurements are given in the following tables 7 and 8 : table 7______________________________________resin + 25 % silica smoke speed ofresins density sound ( m / s ) k ( mdarcy ) r . sub . c ( mpa ) ______________________________________5002 1 . 35 2 . 19 9 . 2 10 . sup .- 3 96 - 102 ( 5 days at 120 ° c .) 5004 1 . 38 2 . 2 6 . 1 10 . sup .- 3 53 - 59 ( 5 days at 120 ° c .) ______________________________________ table 7______________________________________resin + 50 % caco . sub . 3 speed ofresins density sound ( m / s ) k ( mdarcy ) r . sub . c ( mpa ) ______________________________________5002 1 . 54 2 . 2 9 . 2 10 . sup .- 2 126 - 131 ( 5 days at 120 ° c .) 5004 1 . 55 2 . 4 4 . 41 10 . sup .- 7 49 ( 5 days at 120 ° c .) ______________________________________ the initial resin formulations having densities of the same order of magnitude , in the region of 1 . 1 , the density values of the cementing material only depend on the type and on the nature of the filler added . for example , according to tables 7 and 8 , with 25 % of silica smoke , the density obtained is in the 1 . 35 - 1 . 38 range , and with 50 % of caco 3 , the density obtained is in the 1 . 54 - 1 . 55 range . the silica smoke and the carbonate having the same grain size , the materials have comparable permeabilities for each type of resin despite the great difference in amount . from a furfuryl alcohol modified resin , a compressive strength increase is measured between the two types of fillers , due to the difference in the proportion of filler added .