## 5 Conclusions  
The HPHT field is a complicated field to be explored. Progressive preparation is a significant aspect for successful exploration, and modified techniques should be regularly occupied to address the HPHT concerns. The HPHT zone conditions the drilling of wells in many circumstances, for instance, the high temperature caused the slurry to become sensitive, so the setting time of slurry is extremely lessened, causing the cement to thicken quicker than in normal temperature wells. High pressure, on the other hand, has consequences on both the well and drilling fluid. If the pressure is not being predicted appropriately, the designated casing will not be capable of enduring the formation pressure, leading to a breakdown of the casing in the well and, thus, causing a kick. This study utilized the integration of several techniques to characterise the reservoir properties of the HPHT zone in the Sepat field. The workflow involved techniques of rock physics study, pre-stack seismic inversion, SQp and SQs attributes and ANN application for a elastic environment. The Lame constant and shear modulus are more sensitive to variations in porosity and lithology and allow for more accurate reasoning about filling in pore spaces than P- and S-impedances alone. The interpreter was able to identify the most prospective zones inside the sequence by extracting and analysing inversion attributes. SQp and SQs attributes provided us with the information about sand and shale lithology and fluid distribution. Furthermore, the application of 3D models consisting of P-impedance, S-impedance, density, Vp/Vs ratio, and SQp, SQs attributes as the main input for ANN modelling allowed obtaining insight into the distribution of porosity in HPHT zone of Sepat field. The integrated approach succeeded to predict rock properties and reservoir porosity away from the well in the HPHT zone of the Sepat field. The results suggested that the one possible reservoir is identified, located in between the Top H and H 60 horizons on the west of the study area at the location of XD-2 well. Visible alternate layers of sand and shale are observed in the study area. The sandy reservoirs in the HPHT zone are characterized by porosity ranging from 23% to 76% within 2000 to 2900 ms. The usage of novel SQp and SQs attributes as input for ANN modelling proved its effectiveness in improving the lateral  
Figure 26: Averaged porosity data horizon slice within interval between Top H and H60 horizons. continuity of the porosity prediction related to delineated lithology and fluid distribution. By characterising the reservoir properties away from wells in the HPHT zone, it is hoped that the oil and gas industry can drive the limits to deeper depths and in hotter wells in the continuing exploration for new sources of hydrocarbons. Conceptualisation, G.Y., N.N.A.A.N.M.H. and N.F.S. ; methodology, G.Y., N.N.A.A.N.M.H. and N.F.S. ; software, G.Y., N.N.A.A.N.M.H. and N.F.S. ; validation, G.Y., N.N.N.A.A.N.M.H. and N.F.S. ; formal analysis, G.Y., N.N.A.A.N.M.H. and N.F.S. ; investigation, G.Y., N.N.A.A.N.M.H. and N.F.S. ; resources, M.H. ; data curation, G.Y., N.N.A.A.N.M.H. and N.F.S. ; writing--original draft preparation, G.Y. ; writing--review and editing, N.N.A.A.N.M.H., N.F.S., M.H. and H.S. ; visualisation, G.Y., N.N.A.A.N.M.H. and N.F.S. ; supervision, M.H. and H.S. ; project administration, M.H. ; funding acquisition, M.H. All authors have read and agreed to the published version of the manuscript. This research was funded by UTP fundamental research grant with grant number 015 LCO-348. Not applicable. Authors express their gratitude to the Centre of Seismic Imaging (CSI) at University Technology PETRONAS for valuable resources, facilities and funding. This research was made possible by a UTP fundamental research grant with cost centre 015 LCO-348. We acknowledge PETRONAS for providing the data, CGG company for providing HampsonRussell software and Schlumberger company for providing PETREL software for this research. The authors declare no conflict of interest.