Reservoir Paraffin Precipitation: The Oil Recovery Challenge In Dom Joao Field?

Mezzomo, R.F.; Rabinovitz, Andre

doi:10.2118/99-54

Cited by 2 publications

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“…However, in most cases, the temperature of the injected water is not controlled. Therefore, resulting from the injection of large volume of cold water, a decrease in reservoir temperature is observed (Muslimov et al 1968;Mingareev et al 1968;Mezzomo and Rabinovitz 2001;Rocha et al 2003). The problem of clogging the pore volume of the near-wellbore area with wax resulting from a decrease in temperature is described by Borisov et al (2018), Yusupova et al (2016).…”

Section: Introductionmentioning

confidence: 99%

Formation damage induced by wax deposition: laboratory investigations and modeling

Sandyga

Struchkov

Рогачев

2020

J Petrol Explor Prod Technol

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There are oil fields, wherein favorable conditions for the formation damage induced by wax deposition are created during production. The damage can be expressed by a decrease in porosity and permeability and a reduction in the drainage area. There are only a few unconventional fields, and this makes them unique. To prevent this complication, it is necessary to control the field production. Assuming the presence of such problem, the conventional reserves may turn into difficult oil reserves whose production is problematic, which will compromise the project profitability. The key to the problem is associated with the experimental procedure and research conditions for investigation wax crystallization in oil, being the subject of this paper. The authors showed that the use of WAT measurement technique in an open measuring system is not enough to control wax deposition in the reservoir pore volume. Based on the results of the flooding technique and micro-computed tomography, a digital core, that allows to simulate fluid flow in the porous medium of the core before and after formation damage, has been created. The calculation of the change in the thermal field around the injection well over time, according to the extended Lauwerier's concept, has been carried out. WAT of a wax-bearing solution was measured by the rheology method using an open measuring system (plate-to-plate measuring system under atmospheric pressure), and the dependence of viscosity versus temperature was obtained during experimental studies. The temperature was decreased from 60 to 10 °C at a cooling rate of 1 °C/min. The experiment was carried out at atmospheric pressure and a shear rate of 5 s −1 . Also, filtration technique and micro-computed tomography were used. The dependence of the pressure gradient versus temperature and the pore throat diameter distribution functions for the initial core and core with organic scales were obtained. The flooding experiment was carried out at a constant flow rate of 0.5 cm 3 /min and confining pressure of 4.1 MPa. The temperature was decreased from 40 to 33 °C at a cooling rate of 1 °C/h. The inflection points on the curves viscosity versus temperature and pressure gradient versus temperature confirm the WAT. The results of the laboratory experiments showed that WAT, measured by the rheology method is 3-4 °C lower than WAT, measured by the flooding technique. The results of the micro-computed tomography showed that initial porosity decreased from 9.0 to 2.1% as a result of wax deposition. The pore throats with diameters from 20 to 70 μm are involved in the clogging with wax. The calculation results confirmed the possibility of cooling the near-wellbore area of injector to a temperature equal to WAT and the cold front movement to the producing wells. The production profiles calculated based on the models of porosity and permeability reduction, showed that wax deposition in the near-wellbore area can cause a significant decrease in the productivity index. An effective remediation technology for injection wells ...

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Section: Introductionmentioning

confidence: 99%

Formation damage induced by wax deposition: laboratory investigations and modeling

Sandyga

Struchkov

Рогачев

2020

J Petrol Explor Prod Technol

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Research of Temperature Conditions of Organic Sediments Formation in the Productive Formation at Paraffinic Oil Well Production

et al. 2021

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The paper presents the studies results of the temperature conditions for the formation of organic (asphalt-resin-paraffinic) deposits in the productive formation during the downhole production of paraffinic oil, including the results of experimental studies to assess the temperature of oil saturation with paraffin in the pore space of reservoir rocks. The studies were carried out in order to substantiate and develop a technology for preventing such deposits in the "reservoir - well" system. The results of filtration and rheological studies showed that for the same oil, the wax saturation temperature in the pore space of the reservoir rock could exceed the value of this parameter in the free volume. It was found that for the investigated solutions (models of highly paraffinic oils), the phase transition of paraffin from liquid to solid state, the formation of wax crystals in the pore space occured at a temperature 3-4° C higher than in the free volume. The results of tomographic studies of the core material, performed before and after filtration of a paraffin-containing solution through it with a decrease in temperature, showed that the open porosity of rock samples decreased on average four times due to the clogging of their pore space with paraffin. Based on the results of the filtration experiment and computed tomography, a digital core model was created, which allowed modeling the fluid flow in the pore space of the rock before and after the formation of paraffin deposits in it. The calculations results of the changes dynamics in the thermal field around the injection well confirmed the probability of cooling the bottomhole zone of the well to a temperature equal to the temperature of the onset of wax crystallization, as well as the probability of the cold water front advancing to neighboring production wells, which could cause a significant decrease in the productivity due to the formation of paraffin deposits in pore space of reservoir rocks. The research results are recommended to be taken into account when developing oil fields in conditions of possible formation of organic (asphalt-resin-paraffinic) deposits in the productive formation. This will make it possible to more reliably predict and effectively prevent its formation in the "reservoir - well" system.

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Reservoir Paraffin Precipitation: The Oil Recovery Challenge In Dom Joao Field?

Cited by 2 publications

References 0 publications

Formation damage induced by wax deposition: laboratory investigations and modeling

Formation damage induced by wax deposition: laboratory investigations and modeling

Research of Temperature Conditions of Organic Sediments Formation in the Productive Formation at Paraffinic Oil Well Production

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