SPE 112355 New Agent for Formation-Damage Mitigation in Heavy-Oil Reservoir: Mechanism and Application Y. Wang and A. Kantzas, SPE, University of Calgary; B. Li and Z. Li, China University of Petroleum (East China ); and Q. Wang and M. Zhao, Dongxin Oil Company, Shengli Oil Branch, SINOPEC, P.R.China Copyright 2008, Society of Petroleum Engineers This paper was prepared for presentation at the 2008 SPE International Symposium and Exhibition on Formation Damage Control held in Lafayette, Louisiana, U.S.A., 13–15February2008.This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract Migration of formation fines has been shown to cause production decline in many wells, especially for sand production wells in heavy oil reservoir. Filter cakes in wire wrapped liner, which were formed by the attachment of viscous crude oil blended with formation fines, may block the flow paths of viscous oil. The solution to this problem is appropriate treatment to mitigate this type of formation damage. In this paper the performance at laboratory-scale of a new type of agent for formation damage mitigation is presented and some guidelines for its application including the injected pore volume and injection concentration are provided. The mechanism for damage mitigation with this type of agent in heavy oil reservoir was introduced in detail, it mainly include that this type of agent can reduce interfacial tension between crude oil and water and change the wettability of rock surface, which may lead to the breakaway of resins and asphaltenes attached to the rock surface. By simulation experiments and core flood tests the effectiveness of this type of agent to mitigate the damage in heavy oil reservoir was identified. Simulation experiment results show that, damage mitigation in cores with the permeability higher than 1μm 2 , is more effective than those with the permeability lower than 1 μm 2 , and core flood experiment results also indicate that this type of agent with the concentration of higher than 5% can remarkably increase recovery factor for cores with the permeability higher than 1 μm 2 . Finally some results on the behaviour of its application in heavy oil reservoir are presented. Introduction At present, treatment of oil and gas wells with chemicals and biological enzymes are widely practiced to stimulate the production rate of the wells (Harold, 2003, McRae, 2004, M.A. Siddiqui, 2003, M.B. Al- Otaibi, 2004), principally through the removal of production related damages or by increasing the permeability or conductivity of the rock matrix with natural or induced fracture. Also some chemical agents produced by enzymes in oil or gas well can increase water injection, and control water cut (e.g., water shut-off and profile adjustment) as well as sands. Biological enzyme, a new type and efficient plug- removal agent, shows good application results in such countries as Venezuela and Indonesia, etc. Also very good results have been obtained in wells in China ( Qin, 2002). The enzyme used in this research possesses following superiorities (Qin, 2002, RadEx Technology): •Made from DNA micr obes, chosing DNA nutrition as a protein base and biological liquid enzyme as non living catalyst which facilitates the entire biological reactions. •Changing rock wettability, where oil is trapped among the clusters of rocks and initially difficult to extract, could be produced. •Neither affect ed by pH and salinity of the formation fluid, nor affec ted by reservoir temperature and pressur e. •When it is applied into formation, it would not changing porosity and permeability of rocks. •Environmental friendly, pH 5-7, non pathogenic, dissolves in water, doesn’t dissolves in oil.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
New Agent for Formation-Damage Mitigation in Heavy-Oil Reservoir:Mechanism and ApplicationY. Wang and A. Kantzas, SPE, University of Calgary; B. Li and Z. Li, China University of Petroleum (East China);and Q. Wang and M. Zhao, Dongxin Oil Company, Shengli Oil Branch, SINOPEC, P.R.China
Copyright 2008, Society of Petroleum Engineers
This paper was prepared for presentation at the 2008 SPE International Symposium and Exhibition on Formation Damage Control held in Lafayette, Louisiana, U.S.A., 13–15February2008. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not beenreviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, itsofficers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission toreproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
AbstractMigration of formation fines has been shown to cause production decline in many wells, especially for sand production
wells in heavy oil reservoir. Filter cakes in wire wrapped liner, which were formed by the attachment of viscous crude oil blended with formation fines, may block the flow paths of viscous oil. The solution to this problem is appropriate treatment tomitigate this type of formation damage.
In this paper the performance at laboratory-scale of a new type of agent for formation damage mitigation is presented andsome guidelines for its application including the injected pore volume and injection concentration are provided.
The mechanism for damage mitigation with this type of agent in heavy oil reservoir was introduced in detail, it mainlyinclude that this type of agent can reduce interfacial tension between crude oil and water and change the wettability of rocksurface, which may lead to the breakaway of resins and asphaltenes attached to the rock surface.
By simulation experiments and core flood tests the effectiveness of this type of agent to mitigate the damage in heavy oilreservoir was identified. Simulation experiment results show that, damage mitigation in cores with the permeability higher
than 1μm2
, is more effective than those with the permeability lower than 1μm2
, and core flood experiment results also indicatethat this type of agent with the concentration of higher than 5% can remarkably increase recovery factor for cores with the
permeability higher than 1μm2. Finally some results on the behaviour of its application in heavy oil reservoir are presented.
IntroductionAt present, treatment of oil and gas wells with chemicals and biological enzymes are widely practiced to stimulate the
production rate of the wells (Harold, 2003, McRae, 2004, M.A. Siddiqui, 2003, M.B. Al-Otaibi, 2004), principally through the
removal of production related damages or by increasing the permeability or conductivity of the rock matrix with natural or
induced fracture. Also some chemical agents produced by enzymes in oil or gas well can increase water injection, and control
water cut (e.g., water shut-off and profile adjustment) as well as sands. Biological enzyme, a new type and efficient plug-
removal agent, shows good application results in such countries as Venezuela and Indonesia, etc. Also very good results have
been obtained in wells in China (Qin, 2002).
The enzyme used in this research possesses following superiorities (Qin, 2002, RadEx Technology):
• Made from DNA microbes, chosing DNA nutrition as a protein base and biological liquid enzyme as non living catalyst
which facilitates the entire biological reactions.
• Changing rock wettability, where oil is trapped among the clusters of rocks and initially difficult to extract, could be
produced.
• Neither affected by pH and salinity of the formation fluid, nor affected by reservoir temperature and pressure.
• When it is applied into formation, it would not changing porosity and permeability of rocks.
• Environmental friendly, pH 5-7, non pathogenic, dissolves in water, doesn’t dissolves in oil.
C = concentration of biological enzyme solution (dimensionless, by volume)
θ = contact angle (degree)
c p = capillary pressure (Pa)
1 K = permeability of core after blocking (μm
2 )
oW = work of adhesion for oil phase (mN/m)
0 K = initial permeability of core (μm
2 )
2 K = permeability of core after antiblocking (μm2 )
wW = work of adhesion for water phase (mN/m)
woσ = interfacial tension between oil and water (mN/m)
r = radius of capillary tube (m)
Acknowledgements
The authors would like to thank Y.Guo for the time he committed to helping with the simulation of these experiments. His
advice and support made this portion of the paper possible. We also acknowledge Dongxin Oil Company, Shengli oil field,
SINOPEC for its permission to publish this paper.
References
1. Anderson, William G. [A], Wettability Literature Survey – Part 1: Rock/Oil/Brine Interactions and the Effects of Core Handling on
Wettability, JPT, October 1986, pg 1125 – 1144.
2. Anderson, William G. [B], Wettability Literature Survey – Part 2 Wettability Measurement, JPT, November 1986, pg 1246 – 1262.
3. Craig, F.F., The Reservoir Engineering Aspects of Waterflooding; monograph series (1971), SPE, Richardson, TX.
4. Harold D. Brannon, Robert M., Paul S.Carmon et al, Enzyme Breaker Technologies: A Decade of Improved Well Simulation; SPE
84213, SPE Annual Conference and Exhibition held in Denver, U.S.A, 5-8 October 2003.5. J.A McRae, S.M. Heath, C.Strachan et al, Development of an Enzyme Activated, Low Temperature, Scale Inhibitor Precipitation
Squeeze System; SPE 87441, the 6 th international Symposium on Oilfield Scale held in Aberdeen, UK, 26-27 May 2004.
6. M.A. Siddiqui, H.A. Nasr-EI-Din, Saudi Aramco, Evaluation Of Special Enzymes As A Means To Remove Formation Damage
Induced By Drill-In Fluids In Horiztonal Das Well In Tight Reservoir; SPE 81445, SPE 13th Middle East Oil Show And Conference
held in Bahrain 5-8 April 2003.
7. M.B. Al-Otaibi, H.A. Nasr-El-Din, and M.A. Siddiqui, Saudi AramcoChemical Treatments to Enhance Productivity of Horizontal and
Multilateral Wells: Lab Studies and Case Histories; SPE89467, 2004 SPE/DOE Fourteenth Symposium on Improved Oil Recovery held
in Tulsa, Oklahoma, U.S.A., 17-21 April 2004.
8. Pingping Shen, Experimental Technology of Petrophysics; Oil Industry Press, P.102-104, 1995.