Enhance Oil Recovery Essay

Abstraction

Chemical Enhanced Oil Recovery ( EOR ) processes received more attendings presents. Crude Terephthalic Acid ( CTA ) as a chemical compound is used for deluging here as an option to the traditional hydrolyzed polyacryl amide ( HPAM ). Crude Oil samples from an Persian oil field were used during the implosion therapy trials. Sand packed theoretical accounts utilizing two different sizes of sand chiefly 50 and 100 meshes were employed in this probe.

A comparing between H2O implosion therapy and CTA implosion therapy as a secondary oil recovery procedure revealed that the recovery was improved by 10 % when CTA was used. The consequence of assorted injection rates and different concentration of chemical solutions on the recovery factor have been checked. Besides, experimental consequences improved the surfactant behaviour of the CTA solution in H2O. Furthermore, at third province, Sodium Dodocyl Sulfate ( SDS ) as an anionic wetting agent was flooded. Experiments showed that recovery factor increased by 5 % OOIP while utilizing SDS.

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Keywords: Chemical deluging – EOR- CTA-SDSSand packed theoretical account

Introduction

Polymers can typically be added to the injection H2O flooded through a reservoir to accomplish IOR. The intent of this additive is to barricade & A ; lsquo ; main roads ‘ for the injection H2O in the reservoir in order to alter and optimise flow forms. With the other technique, wetting agents ( detergents ) are added to injection H2O to & A ; lsquo ; wash out ‘ more oil in the reservoir. More specifically, polymers increase sweep efficiency by bettering the mobility ratio. Wetting agents, for their portion, enhance microscopic recovery by cut downing capillary forces in add-on to hiking sweep efficiency. Conventional polymers help to raise the viscousness of the injection H2O, whilst wetting agents cut down interfacial tenseness between oil and H2O. Petroleum applied scientists used polymer solutions so that it can brush the more country of oil-bearing reservoir and it can detain the discovery clip as good. during a standard H2O inundation, breakthrough clip comparatively come up fast and H2O thumbing take topographic point into the oil forepart because of high mobility of H2O relation to oil, therefore its sweep efficiency will be low [ 3-4 ].

Polymer is added to injecting H2O so that it can increase the viscousness of solution because of its high molecular weight and as a consequence of that, the thumbing consequence will be reduced and the sweep efficiency can be improved [ 5 ]. Hydrolyzed poly acryl amide ( HPAM ) and xantan gum as man-made and natural polymer severally, are normally used in polymer deluging both in field and in pilot undertakings. In 1964, Pye and Sandi established the fact that polymer implosion therapy can increase oil recovery compared to H2O implosion therapy, they expressed that partly hydrolyzed poly acryl amide ( HPAM ) can cut down the mobility of displacing H2O with increasing its viscousness and better the sweep efficiency of deluging procedure [ 6 ].

Fouling and Wang ( 2006 ) used high concentration of HPAM polymer solution during deluging surveies for Canadian oil field and illustrated the promising consequence of HPAM to increasing recovery factor to around 21 % of the originally oil in topographic point [ 7-8 ].Alkaline-surfactantpolymer ( ASP ) implosion therapy is studied by Zhang and Halliburton ( 2006 ) during the EOR procedure of a Chinese oil field and improved consequence of combination compared to polymer deluging lonely [ 9 ]. Kotlar and Selle ( 2007 ) studied the influence of combination of polymer ( mobility control agent ), surfactant ( cut downing IFT agent ) and a little bi-functional molecule ( increasing solubility agent and cut downing salt consequence ) during deluging to heighten oil recovery factor and deduced that oil recovery can be increased by 20 % OOIP [ 10 ].

Tabary and Bezin ( 2007 ) investigated the improved oil recovery techniques and remarked that chemical procedure plays an of import function in retrieving upswept oil by bettering the mobility ratio and cut downing residuary oil impregnation during procedures such as polymer implosion therapy, wetting agents polymer implosion therapy ( SP ) and alkalic / wetting agent /polymer ( ASP ).Basically surfactants cut down the interfacial tenseness between oil & A ; H2O and mobilise the residuary oil impregnation [ 11 ]. In 2007 Lakatos and Toth studied the viscoelastic wetting agents as mobility – control agents to heighten oil recovery. Their experiments showed that the viscoelastic wetting agent could be replaced by traditional mobility control agents because they could cut down IFT and command the mobility ratio at the same time [ 12 ]. Crude Terephtalic Acid ( CTA ) was used in this survey as a macro monomer that can increase H2O viscousness because it belongs to polyesters household with comparatively high molecular weight. In add-on, SDS was selected to deluge in third province in order to rinse out the residuary oil after polymer implosion therapy through the sand packed theoretical account.

CTA Specifications

CTA which is an abbreviation for “ Crude Terphitalic Acid ” is one isomer of the three phthalic acids. It is largely used as a trade good chemical, well as a beginning compound for doing of polyester ( specifically PET ) which its belongings given in table 1. Addition to good solubility of CTA, it is stable in high temperature around 2800C. It has the chemical expression C6H4 ( COOH ) 2 ( Figure1 ) and known as 1, 4-benzenedicarboxylic acid as good. CTA can heighten the viscousness of H2O when is augmented. Therefore, it can be a campaigner during chemical deluging procedure to better oil recovery factor.

SDS Specifications

Sodium dodecyl sulphate ( SDS or NaDS ) or sodium lauryl sulphate ( SLS ) is an anionic wetting agent with molecular expression C12H25SO4Na. The molecule has a tail of 12 C atoms, attached to a sulphate group, giving the molecule the amphiphilic belongingss required of a detergent ( figure 2 ). SDS is likely the most researched anionic wetting agent compound. Sodium lauryl sulphate can work out trapped oil in porous media and hence, found an drawn-out use in reservoir technology field. The critical micelle concentration ( CMC ) in pure H2O at 25 & A ; deg ; C is 0.0082 M, and the collection figure at this concentration is normally considered to be approximately 50. The micelle ionisation fraction ( a ) is around 0.3 ( or 30 % ).

Experimental set up

To look into the polymer-surfactant EOR procedure, a sand packed column was employed in this survey. A glassy column with inside diameter of 2.5 centimeter and tallness of 25 centimeter was used as the sand battalion holder. Two metallic meshed distributers were positioned on the both terminals of the column. The entryway and issue parts of the theoretical account were equipped with rims and valves to command the implosion therapy rate. Silicate sand with mesh Numberss 50 and 100 are selected as porous media. First, the sand was washed and allowed to dry in free air for 2 yearss. Then, it was poured into the sand battalion bit by bit and was packed good. When the sand battalion holder became full, the terminal rim was closed and so was connected to a CO2 storage armored combat vehicle and the CO2 was allowed to flux through the sand battalion for about 15 proceedingss to wholly throw out the entrapped air.

Then it was flooded with H2O and during H2O deluging the permeableness of the sand battalion was measured using a changeless H2O caput. The water-flooded sand battalion was so flooded by oil utilizing a really precise syringe pump and 4 to 5 pore volumes of the oil was allowed to go through through it. At this clip the sand battalion has been stand foring an oil reservoir that has connate H2O and ready to prove ( figure 3 ). Assorted CTA solutions were injected in secondary province until no more oil would go forth the theoretical account and during the trial, the volume of oil and polymer solution which were traveling out the theoretical account and besides the clip of depletion were recorded. At the third province, SDS was flooded until no more oil could go forth the theoretical account and recovery factor was calculated for SDS implosion therapy every bit good.

CTA Helpfulness

In order to happen out how good the CTA will make, a comparing between it and H2O is made during flooding procedure and the consequence are shown on figure 4. As one can see, the CTA implosion therapy has more recovery factor around 10 per centum against pure H2O injection. Besides, because of the production of CTA near the Persian oil field ; it is opted for this survey during deluging procedures. Water implosion therapy can be replaced by CTA deluging in secondary phase because during of trials, there are neither marks of surface assimilation on sand surface nor decrease of absolute permeableness.

Experiments

Crude Oil samples from an Persian oil field are selected to be used during the implosion therapy trials. CTA solutions were produced in concentrations of 100,250 and 500 ppm. Because of low solubility of CTA in ambient temperature, the solutions were heated up to 700 C while it was stirred. Fortunately, the solutions would hold been unvarying and stable during the trials. In attempts to look into the consequence of solution viscousness on recovery factor, three different concentrations were prepared. Table2 shows the solution belongingss. Experiments were performed as antecedently described. Solutions with different concentrations were injected in a changeless rate ( 0.2cc/min ) and four trials were done in changeless concentration ( 250 ppm ) at different rates ( 0.2, 0.6, 0.8, and 1 cc/min ). Table 3 illustrates the word pictures of experiments. In third province, SDS are injected in changeless concentrating ( 2500 ppm ) and assorted flow rate to obtain the consequence of flow rate on effectivity of SDS deluging in third province.

IFT decrease belongings of CTA

In order to look into the IFT decrease belongings of CTA solution, after fixing the theoretical account a 250 ppm solution of HPAM was injected in secondary phase until no more oil can go forth the theoretical account and so a solution of CTA with 250 ppm concentration was injected in third province. Experiment showed that the 250 ppm solution of CTA increased the viscousness of H2O up to 2.5 cp which is less than the HPAM, but it could retrieve more oil from the sand packed theoretical account about 3 % ( figure 5 ). Therefore, this may be attributed to surfactant behaviour of CTA. In add-on theoretically CTA belongs to polyester groups which make soap froth when solve in H2O.

Consequence of concentration of shooting solution on recovery factor

Injections of CTA solution with three concentrations were done. Injections were making until no more oil could go forth the theoretical account. It is expected that the solutions with more concentration can retrieve farther original oil in topographic point from the sand packed theoretical account. During these trials, SDS was injected in changeless concentration ( 2500 ppm ) every bit good. The consequences of injection with assorted concentrations are shown on figure 6. Since more syrupy solution will displace oil across the theoretical account ideally and occupy more country of the theoretical account, the discovery clip will detain and the syrupy thumbing consequence will be mitigated. Therefore, the recovery factor and sweep efficiency will lift. The consequences from the experiments, besides, verify this physical construct

Consequence of injection rate on recovery factor

CTA and SDS were flooded at three rates of injection in order to happen out the relation of deluging rate and recovery factor. Injecting of high rate solution which expected to short-circuit the majority of oil can besides enforce more force per unit area bead on porous medium. Therefore, the fingering effects may farther be observed every bit good as coning phenomenon will be included because of unbalancing between gravitative forces and syrupy forces at high rates. The consequences are exhibited in figure 7. Since high rate of injection cause to brush less country of theoretical account and besides, the motion of solution through the theoretical account is more longitudinal, the discovery clip will diminish and recovery factor will cut down every bit good.

Salinity consequence on efficaciousness of solution

By and large proved that the concentration of anionic compounds such as Na+, Ca2+ and Mg2+ have some effects on implosion therapy procedures which are imposed on oil reservoirs to better recovery factor. Salinity which specially means concentration of Na+ has a drawback on Hydrolyzed Polydacryl Amide ( HPAM ) efficiency during polymer implosion therapy and reduces the its helpfulness, hence HPAM should be used for such reservoirs which have low seawater concentration. However, CTA shows opposition against salt up to 2500ppm. Figure 8 illustrates a comparing between Dow Pusher 500 polyacrylamide and CTA solutions related to consequence of Nacl concentration on their viscousness [ 4 ]. Hence, CTA could be a suited campaigner for polymer implosion therapy procedures of reservoirs with high salt concentration procedures of reservoirs with high salt concentration.

Consequence of temperature on effectivity of CTA

Adequate temperature ranges in which polymers remain stable without debasement are really sensitive to types of polymer. It is believed that most polymers will be decomposed at high temperatures and so lose their pertinence. Reservoirs with temperature higher than 3000 F should normally be avoided for utilizing polyacrylamide because it loses their viscofying belongings at that temperature. Our experiments showed that CTA could prolong temperature up to 2500 degree Celsius without losing its belongings for the ground that it is contained of benzoic cringle in its construction which is really stable.

Consequences and treatment

This survey concerns chemical deluging procedure to better oil recovery utilizing CTA and SDS as a polymer and surfactant agent severally. A sand packed theoretical account is used to look into the impact of assorted parametric quantities on ability of CTA and SDS to retrieve more oil during deluging procedure. Experiments are designed to analyze effects of injection rate, concentration, temperature and salt on implosion therapy procedures. In add-on, the IFT belongings of CTA is checked every bit good. Taking every thing into the consideration, the undermentioned tax write-offs are obtained:

  • Experiments show that CTA can better H2O deluging efficiency about 10 % at secondary province.
  • Although the viscofying belongings of CTA solution is less compared to HPAM solution but it is used here because of its handiness and economical facets. Furthermore, it showed thermic and electrolyte stableness every bit good as IFT decrease belongings.
  • CTA was flooded in secondary province and it showed no surface assimilation inclination on sand surface or besides ability to cut down absolute permeableness of the theoretical account. Furthermore, the better recovery was received compared to third use of that.
  • CTA deluging at low rates shows more recovery factor because the fingering and bypassing effects will be mitigated.
  • When CTA is flooded at high concentration, more recovery will obtained since a solution with more viscousness will be obtained and mobility ratio will shut to integrity.
  • Since CTA is belong to polyesters groups, its solution exhibits the consequence on decrease of interfacial tenseness between oil and H2O.
  • CTA is able to prolong the high salt every bit good as maintain its stableness belongings at high temperatures.
  • SDS as a surfactant agent could better recovery factor around 5 % OOIP at third province.
  • SDS could retrieve more oil at less rate of injection while used in third province.

Terminology:

  • EOR: Enhanced Oil Recovery
  • SOR: Residual Oil impregnation
  • SWC: Connate Water Saturation
  • OOIP: Original Oil in Topographic point
  • IFT: Interfacieal Tension
  • PV: Pore Volume
  • Releasing factor: Recovery Factor
  • CTA: Crude Terephthalic Acid
  • HPAM: Hydrolyzed Poly Acryl Amide
  • South dakota: Sodium Dodecyl Sulfate
  • HPAM: Hydrolyzed Poly Acryl Amide
  • South dakota: Sodium Dodecyl Sulfate