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Expedite® ServiceQ: Is Expedite compatible with DeltaFrac 140, DeltaFrac 200, and SilverStim LT?A: Yes, Expedite 225 is compatible with all this fluid systemes. However, it may affect the pH, crosslink time, and break time of these fluids. Therefore, proper quality control for verification prior the job is required. Q: Can I pump Expedite in fluid that does not contain proppant?A:Do not use Expedite in any stage that does not contain proppant. The resin will adhere to metal when it is not in the presence of proppant. Q: Is the % coating for Expedite figured on mass/mass or volume/volume??A: Neither. The percent coating is based on volume/mass. A 3% coating requires 3.75 gallons (volume) of Expedite per 1000 lbs (mass) of proppant. If you convert the volume to cc’s and the weight to grams you will find the percentage is approximately 3% (3.13% is the actual percentage). Q: Is Expedite Compatible with MY-T-Oil V??A: Yes, it is. Q: Can you use a solvent to dissolve the Expedite material (from the wellbore or in the fracture)?A: No. Expedite systems were designed for their purpose. There is not such a type of solvent that can easily destroy the Expedite once it has been cured properly no even in the proppant pack. HF acid or strong oxidizers may soften up the proppant pack, but this is as a result of HF acid reacting with the proppant (sand) underneath the coated resin. HF will have little or no effect on man make proppants. Q: How does the application of Expedite affect the proppant sieve distribution?A: The question regarding the sieve size of proppant after it is coated with Expedite and if it increases the proppant size is a common one. There is a very small increase in the proppant diameter (very, very small) but the same thing happens with Resin Coated proppants. The proppant suppliers will purchase the substrate which is sieved to whatever mesh size is needed (20/40, 30/50, etc.). They then apply resin to the substrate. Once the coating process is complete the proppant is run through a screen that separates any particles that are to large or have “clumped” together. They don’t re-sieve the material. With all that said, if he is concerned that Expedite coated Bauxite may cause a screen-out then the same potential exists with a resin coated Bauxite (like Ceramax P) provided by a proppant supplier. Q: What is the best way to remove expedite coated proppant from the wellbore?A: Generally the use of a motor and mill to clean expedite in wellbores is preferred. Using a motor and a mill is a safer option as compared to using a wash nozzle or a Pulsonix tool. There has been a case in the Gulf Coast where they cleaned expedite in a well using a wash nozzle but that was right after the frac job. You may succeed in washing expedite with a wash nozzle but the safest option is to go with a motor and a mill. It is a cheaper insurance for the customer as he is saved by the additional cost of another CT trip with motor / mill if the wash nozzle doesn’t do the job. The mill size will be further dictated by any restrictions in the well. Mills generally used for drilling cement in wells are good like bare claw mills or mills with tungsten carbide inserts. Q: Can you use Pulsonix tool to remove Expedite coated proppant from the wellbore.A: We have used a Pulsonix tool to clean out an Expedite pack under certain circumstances (immediately after the job). This would depend on how long the material has been allowed to cure before trying to remove it. We have had pretty good luck with the Pulsonix tool going through hard scale and packed sand bridges, but we are only talking about a few feet at a maximum. Considering multiple hundreds or even thousands of feet of Expedite treated proppant it would probably not be financially feasible when compared to mechanically removing the sand with a mill, since the penetration rate could be less than a few feet a day as opposed to a few hundred feet a day with a good motor and mill. Also, keep in mind that most of the time, the Pulsonix tool is used in conjunction with an acid treatment, so you are getting the benefits of the acid and the pressure wave oscillation. Q: How do we handle flowback if the well screens out?A: If a well screens-out, the procedure we have followed is flow-back for immediate clean-up but there is a stipulation. If the well screens-out during flush then the chances are the well will be shut-in for the recommended period of time and allow to gain some CS. We have been flowing back at reduced rates immediately after screenout. We would like to keep the flowback rate around 1BPM or less. Once we get bottoms up we may shut the well in for a couple of hours to allow the Expedite to gain some compressive strength. The table below shows the Simulated Consolidation of Expedite in the Wellbore with 2% Expedite 350 in Sirocco frac fluid. NC stands for No Consolidation. The proppant needed to 4 hours @ 250°F to begin to gain some “stiffness”. Time (hrs) Temperature (F) 125 180 200 250 1 NC NC NC NC 2 NC NC NC 4 NC NC Stiff 8 170 psi Q: We don’t worry about washing off the Sand Wedge coating when flowing back (i.e. we don’t wait before flowback). So why do we worry about washing off the Expedite??A: SandWedge has its own nature, tenacious characteristic that once coated on a surface it should remain on the substrate. Expedite although sticky but it must depends on a number of ingredients (i.e., surfactant, coupling agent) and ambient conditions (i.e., time and temperature) to help it stay on the surface. We have done the early flowback testing back in ’96 or ’97 for the SandWedge, and the results indicated that there is insignificant loss of coated amount. And when we introduced dry coating SandWedge NT, the performance was even better. Regarding Expedite, we have done the experiments to determine the effect of early flowback of fluid across the proppant pack (coated with Expedite 350) during the first 90 minutes after coating. We saw a significant reduction of the amounts of the resin remaining on the proppant. However, if you allow the proppant pack to remain undisturbed without meddling at temperature for the first 90 min, the amount of resin removed was negligible. Q: Why is the reason for considering Expedite non reducing conductivity?A: Extensive lab test has been published to present the significant Increase in conductivity when using Expedite coated proppant especially at low closure stress. Unlikely than expected, Expedite increases the conductivity instead of decreasing it. The reason behind is that proppant is coated just right before it pumped to the fracture. Expedite can reduce the proppant settling rate in the fracture and hence improve the vertical distribution of the proppant pack, increases the propped-fracture height and expands porosity and permeability in the proppant pack. Similar lab test done with SandWedge shown that treated proppant settles more slowly and less compactly than untreated proppant. The test showed that treated proppant settles and forms a pack that is 10% less dense that untreated proppant. The Expedite treated proppant settles at the form of a vugular packing (figure below), creating empty spaces of high porosity. When the treated is settling in the fracture, Expedite is still tacky similar to the texture of SandWedge. Therefore, it creates resistance to rolling and resulting in pack of lower density. SPE 90398 fig 1 Expedite conductivity comparison test SPE 98088 Fig 4 Expedite conductivity comparison test SPE 82215 Fig 12 Expedite conductivity comparison test SPE 50002 Fig 5 and 6 SandWedge settling test Q: Can I flowback the well after the Expedite job?A: Expedite coated proppant requires a shut-in time period to allow the resin to cure. Since the resin is temperature activated, it will remain liquid (thick) until it reaches its curing temperature. Therefore, no dragging forces (fluid velocity) should be applied to the proppant pack while curing. In order words, it is recommended not to flow back the well until the cure process is finished. This time has been estimated based on previous lab test published in some SPE papers. However, if flowback is required, you should be aware that there is always certain risk involved with early flowback as often applied in force closure procedures. Forced closure practices are doable under restricted conditions of flowback rate and time but they are not recommended. If the frac gel has not been completely broken, the proppant will flow back with the frac gel. Also, grain-to-grain contact cannot be established because all it takes is a thin film of cross-linked gel to prevent the forming of contact point, and thus consolidation of the pack will not be created in the case of Expedite coated proppant, or any resin coated proppant.
Q: We don’t worry about washing off the Sand Wedge coating when flowing back (i.e. we don’t wait before flowback). So why do we worry about washing off the Expedite?A: SandWedge has its own nature, tenacious characteristic that once coated on a surface it should remain on the substrate. Expedite although sticky but it must depends on a number of ingredients (i.e., surfactant, coupling agent) and ambient conditions (i.e., time and temperature) to help it stay on the surface. We have done the early flowback testing back in ’96 or ’97 for the SandWedge, and the results indicated that there is insignificant loss of coated amount. And when we introduced dry coating SandWedge NT, the performance was even better. Regarding Expedite, we have done the experiments to determine the effect of early flowback of fluid across the proppant pack (coated with Expedite 350) during the first 90 minutes after coating. We saw a significant reduction of the amounts of the resin remaining on the proppant. However, if you allow the proppant pack to remain undisturbed without meddling at temperature for the first 90 min, the amount of resin removed was negligible. Q: Can I delay the setting process of Expedite by pumping a chemical into the wellbore after screenout (eg Citric/Acetic acid)?A: Never let Expedite 225 expose to any types of acids, because they will totally ruin your Expedite 225 coated proppant…Acid will prevent Expedite 225 from curing. You can pump large volume of pre-pad to help cool down the well thus slow the curing of the resin, but DO NOT attempt to use acid to slow down the curing of this resin. Q: What is the rheological model that best represents Expedite?A: Expedite 225 and 350 are Newtonian fluids. Q: Why is the reason for considering Expedite non reducing conductivity?A: Extensive lab test has been published to present the significant Increase in conductivity when using Expedite coated proppant especially at low closure stress. Unlikely than expected, Expedite increases the conductivity instead of decreasing it. The reason behind is that proppant is coated just right before it pumped to the fracture. Expedite can reduce the proppant settling rate in the fracture and hence improve the vertical distribution of the proppant pack, increases the propped-fracture height and expands porosity and permeability in the proppant pack. Similar lab test done with SandWedge shown that treated proppant settles more slowly and less compactly than untreated proppant. The test showed that treated proppant settles and forms a pack that is 10% less dense that untreated proppant. The Expedite treated proppant settles at the form of a vugular packing (figure below), creating empty spaces of high porosity. When the treated is settling in the fracture, Expedite is still tacky similar to the texture of SandWedge. Therefore, it creates resistance to rolling and resulting in pack of lower density.
Q: Can I flowback the well after the Expedite job?A: Expedite coated proppant requires a shut-in time period to allow the resin to cure. Since the resin is temperature activated, it will remain liquid (thick) until it reaches its curing temperature. Therefore, no dragging forces (fluid velocity) should be applied to the proppant pack while curing. In order words, it is recommended not to flow back the well until the cure process is finished. This time has been estimated based on previous lab test published in some SPE papers. However, if flowback is required, you should be aware that there is always certain risk involved with early flowback as often applied in force closure procedures. Forced closure practices are doable under restricted conditions of flowback rate and time but they are not recommended. If the frac gel has not been completely broken, the proppant will flow back with the frac gel. Also, grain-to-grain contact cannot be established because all it takes is a thin film of cross-linked gel to prevent the forming of contact point, and thus consolidation of the pack will not be created in the case of Expedite coated proppant, or any resin coated proppant. |
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