EXPERIMENTAL STUDY ON OIL WELL CEMENT RESISTANCE TOWARDS HYDROCHCLORIC ACID ATTACK

• Main Author: KAH KHENG, LIM
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2010
• Subjects: TP Chemical technology
• Online Access: http://utpedia.utp.edu.my/9368/1/2010%20Bachelor%20-%20Expiremental%20Study%20On%20Oil%20Well%20Cement%20Resistance%20Towards%20Hydrochloric%20Acid%20Attack.pdf; http://utpedia.utp.edu.my/9368/
• Institution: Universiti Teknologi Petronas

Hydrochloric acid (HCI) and Hydrofluoric acid (HF) are used in acidizing treatment to stimulate oil and gas production. It is proven that these acids had successfully increased the oil well production worldwide. However, on the other hand, it has been observed that several oil wells, after submitted to acidizing operations, exhibited zonal intercommunication problems. This is attributed to the occurrence of reactions between the hardened cement slurry in the annulus and the acid. The indication of cement deterioration is the motivation of an extensive experimental program to study the involved mechanisms. The objectives of this study are to investigate the effect of curing temperature and pressure towards the compressive strength and acid resistance towards Class G oilwell cement. Various concentration of HCI solution is exposed to cement cube samples under different curing condition for the analysis of samples of hardened cement slurries (2-inch cement cube), aiming the verification of changes in chemical compositions due to acid attack. Also, the tests are conducted on the analysis of the acid solutions, aiming the identification and quantification of the elements liberated from the cement into the acid solutions. The techniques of X-ray fluorescence (XRF) , Scanning Electron Microscopy (SEM) and equipment compressive strength tester are to be used for this purpose. Based on the results, the depth of the acid attack and the influence of the acid solution composition and of the cement chemical composition on the degree of acid attack are to be evaluated. In previous study, it is observed that HCI will react with calcium oxide forming calcium chloride and water. The higher the curing temperature and pressure, the stronger the compressive strength of the sample of cement slurries, leading to the stronger acid attack resistance. This study will enable a better comprehension of the process of acid attack on cement, and consequently a reduction of this problem in the field will be obtained.