Laboratory Researches of the Polymeric Composition in the Pore Space of Bulk Models

Transcription

1 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. Laboratory Researches of the Polymerc Composton n the Pore Space of Bulk Models I. Raupov Assstant Professor Ol and Gas Department, Sant-Petersburg Mnng Unversty, 2, 21-st lne, Sant-Petersburg, Russa. ORCID D. Podoprgora Assstant Professor Ol and Gas Department, Sant-Petersburg Mnng Unversty, 2, 21-st lne, Sant-Petersburg, Russa. Abstract Ths artcle descrbes the results of laboratory fltraton and mcrotomography researches of polymerc composton based on hydrolyzed polyacrylontrle. We detected changes of fltraton and rheologcal propertes of the polymerc composton n the pore spaces accordng to the tme and dstance and to removal of the model away from the bulk end when smulatng the n-stu water shutoff. As a result of the fltraton and mcrotomography researches we proposed a graphc-analytcal method of calculaton of the relaxaton tme of the polymerc composton whch s a vscoelastc lqud. Later t s used to descrbe the flow of vscoelastc lqud n the pore space. The results of evaluaton of the relaxaton tme n dynamc tests n the oscllatng voltage mode and the relaxaton tme value obtaned wth the help of graphcanalytcal method, have hgh precson and relablty, and can be descrbed by the same equatons that allows us the use of the expermental data for the calculaton of fltraton parameters at njecton of vscoelastc lqud. The proposed method of processng the rheologcal, fltraton and mcrotomography researches of hydrolyzed polyacrylontrle can be recommended as a method for descrbng the flow of a vscoelastc lqud. Ths method allows choosng waterproofng composton wth optmum propertes wth regard to ts rheologcal and fltraton propertes and modes of ts njecton nto productve formaton, t allows to estmate the permeated volume of gel, ts dstrbuton n the pore space, change of rheologcal propertes durng fltraton, pressure gradent of njecton at dfferent tme ponts and dfferent parts of the pore space. Keywords: n-stu water shutoff, polymerc composton, fltraton researches, mcrotomography researches, rheologcal researches. INTRODUCTION For a more detaled study of the process of fltraton and penetraton of the polymerc composton nto the pore space, we offered mcrotomography researches [1] of bulk models after njecton of water solatng composton wth a radopaque substance. MAIN PART MICROTOMOGRAPHY RESEARCH METHODS Durng the mcrotomography research of core-samples [2,3], n ths case of bulk model, the presence of a model of formaton water n t, of the polymerc composton, and possbly entraned ar brngs up a problem of the precse and clear separaton of these phases when takng the results of experments. To do ths, the radopaque substance s used. For the water-soluble reagents the odne-contanng compounds are often used (for example, sodum odde, potassum odde). We used potassum odde accordng to GOST (State Standard) as an X-ray contrast agent. The concentraton of KI was chosen expermentally takng nto account the absorpton coeffcent of X-ray produced by bulk model materal. To make a clear vsualzaton and to dentfy the saturatng substance n the composton of the model, t s necessary that the X-ray densty of the saturatng lqud was much larger than the X-ray formaton densty). So, we determned that addng 0,5 wt%. of potassum odde to the polymerc composton results n gettng a radopaque mage of system "bulk model polymerc composton model of formaton water". 365

2 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. Mcrotomography researches were conducted on a computer hghenergy mcrotomograph SkyScan 1173 at the Department of Hstorcal and Dynamc Geology of the Mnng Unversty. Three-dmensonal vsualzaton of bulk models s presented n fgures 1, 2. Fgure 1. Vsualzaton of bulk model 8 after njecton of the polymerc composton n the three-dmensonal space (К perm=8,11*10-3 μm 2 ) program for a full two-dmensonal and threedmensonal quanttatve mage analyss. The followng parameters were obtaned: pore volume, porosty, specfc area, volume equvalent dameter (pore dameter), etc. All these parameters were obtaned for each of the pores wthn the acceptable resoluton of the nstrument, that condtons a large amount of data. The most valuable parameter s the pore dameter whch determnes the pore volume. There are varous patterns to descrbe the pore spaces of the formaton. The most relevant s the representaton of the pore space as conductng channels [4]. For a more accurate calculaton of the volume of the permeated polymerc composton, the bulk model was provsonally dvded nto equal cylnders each 2.5 mm hgh. The calculaton of the volume of permeated polymerc composton V pol s reduced to summng volumes of these channels of dfferent dameters flled wth waterproofng composton: n V pol = l å S (1) =1 l segment length (l=2,5 mm), mm; S area of the -th channel, mm 2, whch s defned by the formula: Fgure 2. Vsualzaton of bulk model 2 after njecton of the polymerc composton n the three-dmensonal space (К perm=20*10-3 μm 2 ) The permeated polymerc composton wth potassum odde has a lghter colour, as t has a hgher X-ray densty than the surroundng area of the bulk model. To separate one thng from another the area wth water solatng composton s marked wth a gray lne. The bulk models tomograms show that the polymerc composton has dfferent ways of penetraton nto the pore space: at the entry the composton s more sold (hgher contrast) whle n the remote parts the composton s present n smaller amounts (lower contrast). RESULTS OF THE MICROTOMOGRAPHY RESEARCHES Interpretaton and analyss of the obtaned results of mcrotomography researches were carred out usng CT-analyser S = p d 2 4 d dameter of the -th channel, mm. In case of the sphercal shape of the pore, the volume of the permeated polymerc composton V pol can be determned by the formula: (2) V pol = 4 3 p å d (3) When analyzng the amount of pores, ther dameters were grouped accordng to the followng dmensons, mm: 0,01-0,015; 0,015-0,02; 0,02-0,025; 0,025-0,03; 0,03-0,035; 0,035-0,045; 0,045-0,05; 0,05-0,055; 0,055-0,06; 0,06-0,065; 0,0650,07; 0,07-0,075; 0,075-0,08; 0,08-0,85; 0,085-0,09; 0,09-0,95; 0,095-0,1. It was determned that the maxmum number of pores occuped by the polymerc composton corresponds to the range of pores wth a mnmum dameter 0,01-0,015 mm (fgure 3), whch, apparently, are the most senstve to changes of the rheologcal propertes of the polymerc composton: durng the tme t takes before the polymerc composton penetrates to a remote part of the bulk model, the effectve vscosty of the composton ncreases. n =1 366

3 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. Fgure 3. Dstrbuton of the number of pores n the bulk model 8 wth the permeated polymerc composton accordng to ther szes An mportant property of the porous body s the dstrbuton of the volume of pores accordng to ther rad. Ths relaton s descrbed by the ntegral and dfferental curves (Pcture 4). Fgure 5. Dstrbuton of pores accordng to ther szes We bult ntegral curves dependng on the dstance to the nput end of the bulk model. These curves descrbe the dstrbuton of the volume of the permeated polymerc composton accordng to pore szes (fgure 6). The red lne corresponds to the largest possble volume of the pores, wheren the pore dameter s 0,03 mm (the range of pore dameters s 0,01-0,1 mm), whch ndcated the relablty of the results. Fgure 6. Dstrbuton of pore volume of the bulk model 8, that contans polymerc composton, accordng to ther szes (the range of pore dameters s 0,01-0,1 mm) Fgure 4. Integral (top) and dfferental (bottom) curves of pore dstrbuton accordng to ther rad (the numbers are condtonal) The red lne shows the maxmum change of the pore volume per change unt of ther rad that s a sgn of the maxmum pore volume n whch a lqud can be contaned. Fgure 5 shows a normal pore dstrbuton (dfferental curve) n terrgenous reservor accordng to ther szes, where pores wth the szes d Vmaxpore=0,015 mm [5] preval. If we analyze the entre range of pore szes contanng the polymer composton, then the maxmum amount of permeated water resstant composton s n pores wth a dameter equal to d Vmaxgel=0,035-0,11 mm (fgure 7). Ths fact ndcates that not the entre maxmum possble pore volume s occuped by the polymerc composton. Thus, we can make a concluson that when choosng a polymerc composton for n-stu water shut off t s mportant that the composton was able to permeate nto the pores wth a dameter whch corresponds to the maxmum pore volume (n ths case d Vmaxpore=0,03mm): d V max gel d V max pore (4) 367

4 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. d Vmaxpore d Vmaxgel Fgure 7. Dstrbuton of the pore volume of the bulk model 8, contanng polymerc composton accordng to ther szes (the range of pore dameters s 0,01-0,935mm) In case ths nequalty s not satsfed, the polymerc composton does not fll the pore volume completely due to ts hgh effectve vscosty and elastc propertes. Durng the workng process [6] we noted that together wth a decrease n clearance that shapes the pore channel, the effectve vscosty of the polymerc composton ncreases. The Table 1 shows the results of the mcrotomography researches and calculatons. Table 1. Results of radography researches, the pore dameter range s 0,01-0,1 mm Parameter Pore quantty n, unts Pore channel area S, mm 2 Polymer volume V cyl, mm 3 Polymer volume V spher, mm 3 1 Pore szes, мм 0,01-0,015 2 Dstance to the 0-2, ,84 12,09 0,30 3 nput end of the bulk model 5-7, ,37 8,42 0, , ,80 9,50 0, , ,16 10,41 0, , ,72 6,80 0, , ,22 13,05 0, , ,27 5,66 0,14 9 General ,38 65,94 1,64 10 Pore szes, мм 0,095-0,1 11 Dstance to the 0-2, ,63 9,07 1,88 12 nput end of the bulk model 5-7, ,84 12,11 2, , ,69 14,24 2, , ,97 12,41 2, , ,10 15,26 3, , ,80 14,51 3, , ,31 13,27 2,76 18 General ,35 90,86 18,90 368

5 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. THE RESULTS OF FILTRATION AND RHEOLOGICAL RESEARCHES To make an n-stu waterproofng t s necessary to know the changes of fltraton and rheologcal propertes of the polymerc composton at dfferent moments of tme and n dfferent areas of the pore space (fgure 8). The results of complex fltraton, rheologcal and radography researches are presented n table 2. Dstance to the nput end of the bulk model Table 2. Results of complex fltraton and radography researches Tme t, s Effectve vscosty, mpa *s Injecton pressure gradent, MPa/m Volume of the permeated gel, mm , ,47 58, , ,49 45, , ,65 48, , ,32 49, , ,76 38, , , , ,47 33,16 The volume of the permeated polymerc composton was calculated accordng to pore dameters 0-0,015; 0,15-0,02; 0,02-0,025; 0,025-0,03; 0,03-0,035, whch were the most senstve to the changes of rheologcal propertes of gel. It s obvous that the njecton pressure gradent of vscoelastc lqud s not descrbed wth the lnear law of fltraton (fgure 8): wth an ncrease n the effectve vscosty of the polymerc composton the pressure drop ncreases exponentally. k permeablty, µm 2 ; gradp njecton pressure gradent, Pa/m; A constant factor (А=10) (Wsler E. M., 1970); θ relaxaton tme, s.; d referental pore sze, mm. Based on the fact that the parameters of vscoelastcty of the polymerc composton depend on the sze of pore area, we assumed that the thckness of the polymer layer affects the relaxaton tme of gel. For ths purpose we assessed the relaxaton tme of the ntal polymerc composton for dfferent clearance szes: mm, mm, mm (Table 3). As the relaxaton tme we took the tme necessary to make the voltage e (2,72) tmes lower. Fgure 8. Relaton of njecton pressure gradent, effectve vscosty and volume of the permeated polymerc composton to the tme To descrbe the flow of vscoelastc lqud n a porous medum we use a formula that takes nto account the relaxaton tme θ of a referental pore sze d [7]: where ω fltraton speed, m/s; μ vscosty, mpa s; 2 gradp 1 A k d (5) Table 3. Results of determnaton of gel relaxaton tme for polymer layers of dfferent thckness durng the dynamc tests Parameters Value 1 Polymer layer thckness h, mm 0,275 0,975 5,225 2 Relaxaton tme θ, s At the same tme we assessed the polymerc composton relaxaton tme based on the results of fltraton and mcrotomography researches,.e. the nverse problem was solved. We used the formula (5) to calculate the relaxaton tme wth dfferent pore dameters d (based on results of radography researches) and fltraton speed w through these pores wth the known values of njecton 369

6 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. pressure gradent gradp, moblty of polymerc (k/μ) composton at the gven moment of tme: d k gradp A 1 Herewth we calculated the fltraton speed w for each dameter usng the followng formula: Q S Q flud flow rate (polymerc composton) through -th channel, mm 3 /s; S cross sectonal area of -th channel (based on results of radography researches), mm 2. We determned flud flow rate accordng to a certan volume (based on results of radography researches) n each fltraton channel V and tme t : V Q t Tme t spent on a fltraton of polymerc composton nto pore space s determned by boundary condtons, more specfcally by the values of njecton pressure gradent at whch gel fltraton takes place. We used graphcal method to determne boundary condtons for polymerc composton fltraton: 0,18 MPa/m gradp 3,27 MPa/m. (6) (7) (8) For each channel wth dameter d we calculated the values of njecton pressure based on the results of the fltraton researches. As an example, Table 4 shows the calculaton results for gel njecton pressure gradent nto fltraton channels wth average dameters range 0,01-0,015mm, 0,015-0,02mm, 0,02-0,025mm, 0,03-0,035mm. Table 4. Results of calculatons of gel njecton pressure gradent for dfferent pore dameters Average pore dameters d,mm 1 Tme t, s 0,0125 0,0175 0,0225 0, gradp, MPa/m 3 2 1,11 0,70 0,53 0, ,32 2,11 1,58 0, ,65 4,21 3,16 1, ,08 7,02 5,27 2, ,62 10,53 7,90 4,09 We used the above mentoned formulas to calculate the gel relaxaton tme for dfferent dameters of pore channel. (Table 5). Table 5. Results of calculatons of polymerc composton relaxaton tme based on the results of the fltraton and radography researches Parameters Values 1 Average pore dameter d, mm 0,0125 0,0225 0,0325 0,0725 0, Volume of permeated gel V, mm 3 65,94 53,31 90, ,4 252,03 3 Fltarton tme t, s Volume flow rate Q, mm 3 /s 0,7327 0,2468 0,1736 3,5929 0, Cross sectonal area of pore channel S, mm 2 26,38 21,32 36,39 577,74 100,81 6 Fltraton speed w, mm/s 0,0278 0,0116 0,0048 0,0062 0, Relaxaton tme θ, s 0,14 0,59 2,08 3,56 10,94 8 Average pore dameter d, mm 0,2975 0,4475 0,5975 0,6725 0, Volume of permeated gel V, mm 109,89 33,69 9,17 5,39 4,73 10 Fltarton tme t, s Volume flow rate Q, mm 3 /s 0,2642 0,0717 0,0152 0,0094 0, Cross sectonal area of pore channel S, mm 2 43,96 13,48 3,67 2,16 1,89 13 Fltraton speed w, mm/s 0,0060 0,0053 0,0041 0,0044 0, Relaxaton tme θ, s 15,13 25,72 44,13 47,04 64,53 370

7 Internatonal Journal of Appled Engneerng Research ISSN Volume 12, Number 3 (2017) pp Research Inda Publcatons. RELATION BETWEEN CALCULATED DATA AND LABORATORY RESEARCHES RESULTS Then we compared the values of the relaxaton tme of the polymerc composton, whch we calculated based on the results of mcrotomography and fltraton researches, and the ones we determned n dynamc tests n gel oscllatng voltages mode (fgure 9). Fgure 9. Relaton of relaxaton tme and pore dameter (polymer layer thckness) [4] Tronov V.P. Water cleanng of dfferent types for further usage n formaton pressure mantenance system. / V.P. Tronov, А.V. Tronov. Kazan: Publshng House «FEN», p. [5] Ibatulln R.R. Technologcal processes of ol feld development. М.: JSC «VNIIOENG», p. [6] Raupov I.R. Technology of n-stu water shut off of terrgenous reservors usng polymerc compostons and optcal method for process control: thess research of Doctor of Scence: / Raupov Inzr Ramlevch. Sant- Petersburg, p. [7] Mrchnk М.F. Physcal and geologcal problems of enhance of ol and gas recovery. / М.F. Mrchnk, А.H. Mrzajanadze, Zheltov Yu.V. and others. М.: Publshng House «Nedra», p. The calculated values and expermental results of determnaton of the relaxaton tme of the ntal polymerc composton are practcally equal and are to be descrbed by nearly the same equatons. Ths allows us to use the expermental data to calculate the fltraton parameters at njecton of vscoelastc lqud. CONCLUSION The above descrbed approaches to the complex laboratory researches of polymerc compostons allow us to fnd the composton wth optmum propertes for the n-stu water shut off takng nto account ts rheologcal and fltraton characterstcs and the modes of ts njecton nto the productve formaton. They also allow us to evaluate the volume of the permeated composton, ts dstrbuton n pore space, the changes of rheologcal propertes before and after fltraton, njecton pressure gradent at dfferent moments of tme and n dfferent parts of pore space. REFERNCES [1] Shtyrlyayeva А.А. Prospects and problems of the use of computer mcrotomography for studyng core samples / А.А. Shtyrlyayeva, А.V. Zhuravlyov, А.I. Gerasmova // Petroleum geology. Theory and practce V URL: [2] Sdorovch А.V. Thermomechancal study of amorphous crystallne polymers / А.V. Sdorovch, Е.V. Kuvshnsky // Hgh-molecular compounds V P [3] Ryabokon S.А. Process lquds for completon, mantenance and repars of wells. Krasnodar: JSC SPA «Burenye», p. 371