Poh, Zheng Da creator author. text my 2025 2025 monographic eng xi, 45 pages : illustrations ; During oil well cementing applications, retarders are added to delay the setting time of the cement slurry to achieve pumpability and fluidity. However, in deep and ultra deep oil wells with temperatures exceeding 120 °C, conventional retarders used in the oil industry do not function desirably. Resulting in abnormal gelation of the cement slurry and thickening time reversal. Previous studies synthesized polymer retarders with tartaric acid to overcome these issues. However, at a prolonged temperature polymer degradation occurs and these issues have not been completely eradicated. Also, research on retarders from biomass that can completely inhibit thickening time reversal and abnormal gelation has not been investigated and the mechanisms are still tenuous in literature. Hence, this study was designed to fill these gaps in knowledge. Therefore, in this study lignosulfonate retarder was synthesized from empty fruit bunch (EFB) for high temperature high pressure (HTHP) oilwells. The properties of the retarder were determined via scanning electron microscopy (SEM), Four transform infrared spectroscopy (FTIR), and gas chromatography Mass spectrometry (GCMS). Likewise, the thermal stability of the retarder was investigated using thermogravimetric analysis (TGA). Finally, the performance of the retarder was evaluated. The TGA results revealed that the retarder was stable up to 650 °C. The rheological properties showed a good dispersing effect, reducing cement pastes' dynamic yield stress and plastic viscosity. The results demonstrate the feasibility of using EFB as a retarder for HTHP oilwells. specialized Poh Zheng Da Faculty of Chemical and Process Engineering Technology Final Year Report (Bachelor of Technology Mechanical Engineering (Petroleum) with Hons ) -- Universiti Malaysia Pahang Al-Sultan Abdullah - 2025 Include bibliographical reference Faculty of Chemical and Process Engineering Technology Dissertations Universities and colleges Dissertations Theses Dissertations THE0010913 (Local) https://umpir.ump.edu.my/id/eprint/48051 https://umpir.ump.edu.my/id/eprint/48051 UMPSA 260806 20260806115316.0 eng