SENSITIVITY ANALYSIS OF ACID SELECTION FOR ACID FRACTURING ON CARBONATE RESERVOIR BASED ON CARBONATE MINERALS

• Main Author: SULAKSONO (NIM : 22208305); Pembimbing : Dr. Ir. Sudjati Rachmat, DEA, RIZKY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20471
• Institution: Institut Teknologi Bandung

Acid fracturing is a well stimulation process in which acid, usually hydrochloric acid (HCl), is injected into a carbonate formation at a pressure sufficient to fracture the formation or to open existing natural fractures. As the acid flows along the fracture, portions of the fracture face are dissolved. Since flowing acid tends to etch in a nonuniform manner, conductive channels are created which usually remain when the fracture closes. <br /> <br /> <br /> The effective length of the fracture is determined by the volume of acid used, its reaction rate, and the acid fluid loss from the fracture into the formation. The effectiveness of the acid fracturing treatment is largely determined by the length of the etched fracture.8 To predict the acid reaction that occurred in acid fracturing for resulting length, width, and conductivity and what is the optimal for acid type, concentrasion, and injection rate for certain formation are very complex. <br /> <br /> <br /> In this thesis, study conducted by injecting plain acid (HCL) or gelled acid (LCA) with 15% -28% concentrasion and injection rate of 10-30 bbl/min in a carbonate reservoir containing limestone minerals 0% -100% and dolomite 0% -100% by using the simulator. From this study analyzed the results of etched half-lengh, etched width, conductivity, and dimensionless fracture conductivity. <br /> <br /> <br /> To find out the optimal of acid fracturing is using rate dimensionless fracture conductivity (FCD), based on research of Cinco-Ley, Samaniego and Dominguez with FCD number is 1.6. If the value of FCD far from 1.6, the acid fracturing result will be relatively bottleneck. In general, gelled acid (LCA) have a higher conductivity values compared with plain acid (HCL). But based on the dimensionless fracture conductivity (FCD), for several carbonate formation, plain acid (HCL) has a greater number of FCD that approach optimal number 1.6. <br /> <br /> <br /> From this sensitivity analysis found that LCA that has a gelling agent to reduce leakoff not always produce good conductivity compared with HCL. The increase in injection rate resulted in increased length of etched frac half-length, but results in lower average width of etching and conductivity. If the concentration of dolomite > 50%, injection rate above 20 bbl/min was not able to make the channel that have conductivity due to the missing acid concentration so that the concentration of acid at fracture wall is none. In general, the increased concentration of acid is able to form a channel that has high conductivity by making the width of etching larger. The optimal type of acid based on Cinco-Ley, Samaniego and Dominguez are for limestone 100% is HCL 28% and 15 bbl/min injection rate with FCD 1.5. For 25% dolomite 75% limestone is 15% LCA with injection rate 10 bbl/min with FCD 1.7. For 50% limestone 50% dolomite is 15% LCA with injection rate 10 bbl/min with FCD 1.4. For 75% dolomite 25% limestone is 28% LCA with injection rate 10 bbl/min with FCD 1. For 100% dolomite is 15% LCA with injection rate 10 bbl / min with 0.9 FCD.