Integrated 3D Acid Fracturing Model for Carbonate Reservoir Stimulation

2013 ◽  
Author(s):  
Xi Wu ◽  
Alfred Daniel Hill ◽  
Cassandra Oeth ◽  
Ding Zhu ◽  
Eduardo Gildin
Keyword(s):  
Carbonate Reservoir ◽  
Acid Fracturing ◽  
Reservoir Stimulation

scholarly journals An innovative concept on deep carbonate reservoir stimulation: Three-dimensional acid fracturing technology

2020 ◽  
Vol 7 (5) ◽  
pp. 484-497
Author(s):  
Jianchun Guo ◽  
Bo Gou ◽  
Nan Qin ◽  
Junsheng Zhao ◽  
Lin Wu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Carbonate Reservoir ◽  
Acid Fracturing ◽  
Reservoir Stimulation ◽  
Innovative Concept

Case Studies of Tight-Gas Carbonate Reservoir Stimulation: Acid Fracturing vs. Propped Fracturing

2006 ◽  
Author(s):  
Xianwen Li ◽  
Zhenfeng Zhao ◽  
Xu Ma ◽  
Xiaoduo Wang ◽  
Huanshun Zhou
Keyword(s):  
Case Studies ◽  
Carbonate Reservoir ◽  
Tight Gas ◽  
Acid Fracturing ◽  
Reservoir Stimulation

Using Advance Acid Fracturing Design to Increase the Production Efficiency in a HPHT Reservoir: A Success Story from Southern Mexico

2021 ◽  
Author(s):  
Frank Figueroa ◽  
Gustavo Mejías ◽  
José Frías ◽  
Bonifacio Brito ◽  
Diana Velázquez ◽  
...  
Keyword(s):  
High Temperature ◽  
Laboratory Tests ◽  
Reaction Rates ◽  
Gas Production ◽  
Carbonate Reservoir ◽  
Fluid Distribution ◽  
Acid Etching ◽  
Southern Mexico ◽  
Acid Fracturing ◽  
Fluid Systems

Abstract Enhanced hydrocarbon production in a high-pressure/high-temperature (HP/HT) carbonate reservoir, involves generating highly conductive channels using efficient diversion techniques and custom-designed acid-based fluid systems. Advanced stimulation design includes injection of different reactive fluids, which involves challenges associated with controlling fluid leak-off, implementing optimal diversion techniques, controlling acid reaction rates to withstand high-temperature conditions, and designing appropriate pumping schedules to increase well productivity and sustainability of its production through efficient acid etching and uniform fluid distribution in the pay zone. Laboratory tests such as rock mineralogy, acid etching on core samples and solubility tests on formation cuttings were performed to confirm rock dissolving capability, and to identify stimulation fluids that could generate optimal fracture lengths and maximus etching in the zone of interest while corrosion test was run to ensure corrosion control at HT conditions. After analyzing laboratory tests results, acid fluid systems were selected together with a self-crosslinking acid system for its diversion properties. In addition, customized pumping schedule was constructed using acid fracturing and diverting simulators and based on optimal conductivity/productivity results fluid stages number and sequence, flow rates and acid volumes were selected. The engineered acid treatment generated a network of conductive fractures that resulted in a significant improvement over initial production rate. Diverting agent efficiency was observed during pumping treatment by a 1,300 psi increase in surface pressures when the diverting agent entered the formation. Oil production increased from 648.7 to 3105.89 BPD, and gas production increased from 4.9 to 26.92 MMSCFD. This success results demonstrates that engineering design coupled with laboratory tailor fluids designs, integrated with a flawless execution, are the key to a successful stimulation. This paper describes the details of acidizing technique, treatment design and lessons learned during execution and results.

Acid Fracture Conductivity Behavior of Tahe Carbonate: High Closure Stress, Long-Term Conductivity, and Composite Conductivity

2014 ◽  
Vol 1042 ◽  
pp. 44-51
Author(s):  
Jia Nye Mou ◽  
Mao Tang Yao ◽  
Ke Xiang Zheng
Keyword(s):  
Creep Deformation ◽  
Contact Time ◽  
Carbonate Reservoir ◽  
Fracture Conductivity ◽  
Acid Rock ◽  
Acid Fracturing ◽  
Closure Stress ◽  
Composite Conductivity ◽  
Conductivity Behavior

Acid fracture conductivity is a key parameter in acid fracturing designs and production performance prediction. It depends on the fracture surface etching pattern, rock mechanical properties, and closure stress. The fracture surfaces undergo creep deformation under closure stress during production. Preservation of fracture conductivity becomes a challenge at elevated closure stress. In this paper, we investigated acid fracture conductivity behavior of Tahe deep carbonate reservoir with high closure stress and high temperature. A series of acid fracture conductivity experiment was conducted in a laboratory facility designed to perform acid fracture conductivity. Gelled acid and cross linked acid with different acid-rock contact times were tested for analyzing the effect of acid type and acid-rock contact time on the resulting conductivity. Closure stress up to 100MPa was tested to verify the feasibility of acid fracturing for elevated closure stress. Long-term conductivity up to 7-day was tested to determine the capability of conductivity retaining after creep deformation. Composite conductivity of acid fracture with prop pant was also carried out. The study shows that the fracture retained enough conductivity even under effective closure stress of 70MPa. The gelled acid has a much higher conductivity than the cross linked acid for the same contact time. For the gelled acid, contact time above 60-minute does not lead to conductivity increase. Acid fracture with prop pant has a lower conductivity at low closure stress and a higher conductivity at high closure stress than the acid fracture, which shows composite conductivity is a feasible way to raise conductivity at high closure stress. The long-term conductivity tests show that the acid fracture conductivity decreases fast within the first 48-hour and then levels off. The conductivity keeps stable after 120-hour. An acid fracture conductivity correlation was also developed for this reservoir.

scholarly journals A rock self-supporting high conductivity acid fracturing technique in a deep carbonate reservoir

2020 ◽  
Vol 570 ◽  
pp. 022005
Author(s):  
Lu Baoping ◽  
Jun Zhou ◽  
Tingxue Jiang ◽  
Shidong Ding ◽  
Linbo Zhou ◽  
...  
Keyword(s):  
Carbonate Reservoir ◽  
High Conductivity ◽  
Acid Fracturing

Integrated Acid Fracture Model with Reservoir Simulation Under Non-Isothermal Condition

2021 ◽  
Author(s):  
Tohoko Tajima
Keyword(s):  
Reservoir Simulation ◽  
Isothermal Condition ◽  
Carbonate Reservoir ◽  
Temperature Sensitive ◽  
Reservoir Model ◽  
Coupled Modeling ◽  
Fracture Conductivity ◽  
Acid Fracturing ◽  
Significant Difference ◽  
Fracturing Process

Abstract Modeling of acid fracturing process is challenging because of the coupled complex effects of flow through porous media and fractures, chemical reaction in a geostatistical base, wormhole propagation, and reservoir heterogeneity. To avoid the complexity, decoupled approaches are commonly used; the reservoir effect is represented by leakoff with a constant leakoff coefficient, and analytical solutions for heat flux from a reservoir is used to avoid complexity. An acid fracturing numerical model is presented that is coupled with a single-phase black oil reservoir simulator for a vertical well in the carbonate reservoir. The coupled acid fracturing model considers fracture propagation, acid transport, and heat transfer. After simulating acid fracturing, the conductivity of the fracture is calculated using empirical correlations, and the productivity is computed by simulating the flow to the well. Non-isothermal condition is assumed to simulate the flow in both the fracture and reservoir because the acid reaction is temperature sensitive. Leakoff from fracture to reservoir is simulated with a reservoir flow model for pressure and leakoff velocity as functions of time and location. Wormhole propagation from the fracture is considered by using empirical equations for wormhole propagation based on leakoff velocity estimated from the reservoir simulation. The benefits of coupled modeling are evaluated by comparing the conventional acid fracturing model which uses a decoupled approach to the numerical acid fracturing model developed in this study. The results show that the coupling reservoir model improves the accuracy of estimated in fracture conductivity. It has been shown that the analytical equations for heat from a reservoir used in literature overestimates the final acid fracture conductivity. Thus, it is suggested to use fully numerically solve fluid flow and energy balance in a fracture and a reservoir. Complex leakoff due to pressure and temperature change with time and wormhole propagation was implemented in the simulator. The wormhole effect was added and the distribution of leakoff coefficient was reasonable. A comparison of simulation results with and without wormholes showed that the significant difference was not observed in acid concentration, but ideal width distribution was lower with wormholes. It is concluded based on the observation of the study that the leakoff from acid fracture represented by a reservoir model with wormhole propagation is important to correctly understand acid fracture efficiency. Simply using a constant leakoff coefficient can lead to significant error and misleading conclusions.

Acid Fracturing Experience In Naturally Fractured – Heavy Oil Reservoir, Bati Raman Field

2021 ◽  
Author(s):  
Mustafa Erkin Gozel ◽  
Serkan Uysal ◽  
Cosan Ayan ◽  
Ugur Yuce ◽  
Egemen Ozturk ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Laboratory Tests ◽  
Reaction Rates ◽  
Carbonate Reservoir ◽  
Production Performance ◽  
Total Production ◽  
Acid Fracturing ◽  
Wide Range ◽  
Fracture Closure ◽  
Naturally Fractured

Abstract Bati Raman field, with an original oil in place of 1.85 billion barrels, is a naturally fractured carbonate reservoir containing 9-13 °API extra heavy oil with viscosities varying from 300 to 600 cp. Not only a wide range of pilot EOR schemes including gas, thermal and chemical methods, but also novel IOR applications have been tried in the field. CO2 injection was a game changer for this reservoir which has been the main drive mechanism since 1987. Since then, various techniques are applied to further improve the production performance of the field. This study focuses on the design and outcome of the pilot acid fracturing treatments in selected three wells in the tighter and less fractured southeastern part of the reservoir. State of the art planning included full evaluation of well integrity, cement bond and open hole logs, geomechanics studies augmented with rock mechanics laboratory tests. Laboratory tests were also conducted focusing on sludge/emulsion forming tendencies and acid reaction rates. Using these results, expected fracture dimensions were predicted along with production forecasts. In all wells, pre-frac calibration tests were conducted to assess stress conditions and fracturing parameter optimization. The treatments were then executed, improving the procedure between each well for acid fracturing. Injections schemes were operationally efficient and various diversion techniques were used to mitigate the presence of naturally fractured zones. Pre and post-job temperature logs helped to evaluate each treatment. The results from the wells were very positive; total production rate increased about fivefold, observed within one month after the treatments. No considerable change in water or CO2 production in the wells was observed which had been one of the most important objectives during the candidate selection process. One well was suspended, which turned out to be one of the producers of the field after acid fracturing treatment. Each well had a different post-frac production performance because of its geological characteristics and flow dynamics, making the study more valuable for better understanding of the process. The wells are still on critical observation to assess the nature of the created fractures and their longevity in the long run. Even after twelve to fifteen months of production, which is the breaking point period for fracture closure, the overall production level of the wells was double compared to pre-frac rates. One well still has a fracture dominated production while other two changed back into its pre-frac rates. Based on these results, acid fracturing campaign was extended in the area which is currently under evaluation.

First Acid Fracturing Unlocks the Production Potential of Tight Tuba Carbonate Reservoir, North Kuwait

2015 ◽  
Author(s):  
A. AL-Hassan ◽  
E. Anthony ◽  
S. Abd El-Aziz ◽  
M. Abdel-Basset ◽  
A. Mokhtar ◽  
...  
Keyword(s):  
Carbonate Reservoir ◽  
Production Potential ◽  
Acid Fracturing
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