scholarly journals Research and Evaluation of a New Autogenic Acid System Suitable for Acid Fracturing of a High-Temperature Reservoir

ACS Omega ◽  
2020 ◽  
Vol 5 (33) ◽  
pp. 20734-20738
Author(s):  
Yang Wang ◽  
Changlin Zhou ◽  
Xiangyi Yi ◽  
Li Li ◽  
Jun Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Acid System ◽  
Acid Fracturing

New Single-Phase Retarded Acid System Boosts Production after Acid Fracturing in Kazakhstan

2018 ◽  
Author(s):  
Dmitriy Abdrazakov ◽  
Mohan Kanaka Raju Panga ◽  
Christopher Daeffler ◽  
Duman Tulebayev
Keyword(s):  
Single Phase ◽  
Acid System ◽  
Acid Fracturing

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.

Addressing Matrix Acidizing Stimulation Challenges in Depleted, High-Temperature, and Acid-Sensitive Sandstone Formations with a High-Performance Acid System

2021 ◽  
Author(s):  
Rao Shafin Khan ◽  
Nestor Molero ◽  
Philippe Enkababian ◽  
Aizaz Khalid ◽  
Malik Anzar Afzal ◽  
...  
Keyword(s):  
High Temperature ◽  
Organic Acid ◽  
High Performance ◽  
Clay Content ◽  
High Energy ◽  
Acid System ◽  
Matrix Acidizing ◽  
Well Production ◽  
Production Trend ◽  
Sandstone Reservoirs

Abstract Acid stimulation in high-temperature sandstone reservoirs with high clay content can lead to undesired results due to secondary and tertiary reactions between treatment fluids and reservoir clays. Although there have been significant advancements in treating clastic formations over the years, high bottomhole temperature (BHT) coupled with high clay content of up to 35% and subhydrostatic conditions still presents a major challenge. A stimulation workflow to address these challenges was adapted to treat and successfully enhance well production in sandstone reservoirs in southern Pakistan. Candidate wells were selected for acidizing treatments based on declining production trend and identification of significant damage skin. X-ray diffraction tests on core samples indicated presence of acid-sensitive clays and calcite. Due to the risk of precipitation from secondary and tertiary reactions, conventional hydrochloric and hydrofluoric acid treatments were not viable options. Core flow testing was conducted to assess the efficiency of alternative acid systems at the reservoir conditions with BHT above 320°F, validating the selection of a high-performance sandstone acid system that was designed to handle undissolved clays in the critical matrix by helping to bind the clays to the pore surfaces, thus preventing them from migrating and plugging the pore throat during flowback. The matrix stimulation campaign included vertical and deviated dry gas wells, completed with 3 1/2-in. to 4 1/2-in. production tubing and 7-in. liner, with perforated intervals averaging 20 ft. Prior to the main acid treatment, high-pressure rotary jetting across the target intervals was conducted by pumping organic acid via coiled tubing. This wellbore conditioning technique allowed maximizing the acid performance by delivering 360° high-energy fluid to clear the perforations of scale and improve injectivity. The main treatment consisted of an organic acid preflush and a high-performance sandstone acid system as the main fluid, followed by a brine post-flush. Throughout the treatment, nitrogen was added to all fluids to facilitate fluid flowback under subhydrostatic conditions. The wells treated using this matrix stimulation engineered workflow yielded sustained production gains from 3 MMscf/D to 3.5 MMscf/D, exceeding expectations by more than 50% and achieving payback periods less than 20 days. The success of the treatment was largely due to the carefully designed stimulation workflow and its flawless execution. Acidizing high-temperature sandstone reservoirs with 30 to 35% clay content is uncommon. The experience gained in southern Pakistan validates the high-performance sandstone acid system as a reliable option for matrix acidizing in hot, acid-sensitive sandstone reservoirs. It also provides a detailed engineering workflow for candidate selection, treatment design, and job execution and evaluation, which can easily be adapted to regions facing similar challenges.

Study on a High-Temperature Delayed Cross-Linked Acid

2012 ◽  
Vol 624 ◽  
pp. 252-255 ◽  
Author(s):  
Xiao Zhao ◽  
Qi Song ◽  
Hai Lin ◽  
Yan Ling Wang ◽  
Zeng Bao Wang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
High Temperature ◽  
Reaction Time ◽  
Influencing Factors ◽  
Reaction Temperature ◽  
Zirconium Oxychloride ◽  
Cross Linking ◽  
Acid System ◽  
Mass Ratio ◽  
Reaction Conditions

A retarded zirconium cross-linking agent ECA-1 was prepared by using zirconium oxychloride, lactic acid， xylitol, and so on, then we got a high-temperature delayed cross-linking acid with cross-linking agent ECA-1 added to EVA-180 gelling acid, cross-linked acid performance and its influencing factors were discussed in details, such as reaction conditions of crosslinker, concentrations of crosslinker and thickener, and so on. The results showed that the obtained cross-linked acid had good temperature-tolerate and shear-tolerate properties when the mass ratio of zirconium oxychloride, lactic acid and xylitol is 1:1.25:0.0208 , the reaction temperature is 50~55°C, the reaction time is 4 hours, the delayed cross-linking time of acid system can be adjusted by changing the dosage of crosslinker and thickener.

Evaluation of Inorganic-Crosslinked-Based Gelled Acid System for High-Temperature Applications

2020 ◽  
Author(s):  
Fares AlOtaibi ◽  
Mohammed Dahlan ◽  
Mohammed Khaldi ◽  
Abdulaziz AlGhamdi ◽  
Ibrahim Al-Hulail
Keyword(s):  
High Temperature ◽  
Acid System ◽  
Temperature Applications

scholarly journals Pre-acid system for improving the hydraulic fracturing effect in low-permeability tight gas reservoir

2021 ◽  
Vol 11 (4) ◽  
pp. 1761-1780
Author(s):  
Nianyin Li ◽  
Fei Chen ◽  
Jiajie Yu ◽  
Peihong Han ◽  
Jia Kang
Keyword(s):  
Hydraulic Fracturing ◽  
Filter Cake ◽  
Low Permeability ◽  
Tight Gas ◽  
Acid System ◽  
Fracturing Fluid ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Acid Fracturing ◽  
Performance Requirements

AbstractHydraulic fracturing is an important technical means to improve the development effect of low-permeability oil and gas reservoirs. However, for low pressure, low-permeability, tight, and high-clay sandstone gas reservoirs, conventional propped fracturing can cause serious damage to the reservoir and restrict the fracturing effect. The pre-acid fracturing technology combines acid treatment technology with sand-fracturing technology. A pre-acid system that meets special performance requirements is injected before fracturing. The pre-acid reduces the formation fracture pressure and removes clay damage. During acid flowback, the fracturing fluid is promoted to break the gel, dissolve the fracturing fluid residue and polymer filter cake, clean the supporting cracks, and effectively improve the fracturing effect. This study analyzes the process principle and technical advantages of the pre-acid fracturing technology based on the laboratory evaluation of the fracturing damage mechanism of low-permeability tight gas reservoirs. To meet the performance requirements of low-permeability tight gas reservoirs and pre-acid fracturing technology, a set of polyhydrogen acid system with long-lasting slow reactivity, low damage, and low corrosion was developed and used as the pre-fracturing acid. The acid system is mainly composed of the main agent SA601 and the auxiliary agent SA701. Then, on the basis of laboratory experiments, this acid system is used as the fracturing pre-acid to evaluate the fracturing improvement effect. The results show that the fracturing fluid system can better dissolve the fracturing fluid filter cake and remove the fracturing fluid damage.

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