Central Faulted Region (CFR), East Flank Region (EFR), and Greater Sirikit East (GSE) are the main production areas in the PTTEP S1 Consession, part of Sirikit Field, the biggest onshore oil field in Thailand. The Lan Krabu Formation is the biggest contributor for hydrocarbon production, defined as a thick fluvio-lacustrine deltaic sequence consisting of thin alternations of mouthbar deposits, channels and Chum Saeng lacustrine claystone. The CFR, EFR and GSE regions are structurally complex, each of which is separated by west dipping, basement rooted main fault. The secondary faults are east dipping antithetic and west dipping synthetic faults which run almost parallel to the main fault. For modelling purposes, detail geological correlation across CFR, EFR and GSE has been established. The correlation utilizes the sequence stratigraphy concept by correlating the flooding surface of the fifth order sequence. The shale interval associated with fifth order flooding surface may inhibit vertical pressure communication or vertical oil movement during production time frame. Given the highly heterogeneous reservoirs in fluvio deltaic environment together with complex faulting system, it is very challenging to build a geological model that represents the detailed geological features of these areas. Selecting the 3D modelling tools is essensial to generate a model with complicated geological features, in a way that reservoir simulation can be performed in an efficient manner. This paper will share challenges prior to and during construction of the 3D geocellular model, as well as various modelling approaches that have been generated with multi-scenarios and multi-realizations tasks. It also demonstrates how pixel, object and multi-points statistics (MPS) based approaches in facies modelling along with the application of continuous and discrete N/G provide alternative input for the reservoir modelling. The result of this study will be used for flow performance evaluation and further dynamic modelling. Introduction Sirikit Field is located in Phitsanulok Basin, Central Plain, onshore Thailand, approximately 400 km north of Bangkok (Figure 1). The Field is the country's largerst onshore oil field located in the S1 concession, currently operated and wholly owned by PTT Exploration and Production. The Field was discovered in 1981 by LKU-A01 well drilled by TSEP (Thai Shell Exploration and Production). In effort to increase the oil recovery, Waterflood has been implemented within the Sirikit Area. The East Flank Region was the first region to be waterflooded starting in 1995. The EFR was selected for a waterflood candidate based on the fact that it had the least amount of faulting among the regions. Water injection in Central Faulted Region just started end of 2010. The Greater Sirikit East is a relatively new area, discovered in 2006, and it is still producing under primary recovery.
Shallow hydrocarbon pays were occasionally encountered above Main Seal, the top seal for Lan Krabu K reservoirs, uppermost main reservoir in the Sirikit Main Field. Shallow hydrocarbon is trapped in the Lower Yom and PTO Formations sandstone reservoirs which in the past were rarely considered to be drilling target in the field. Some accumulations were discovered unintentionally while drilling into the deeper Lan Krabu reservoirs. In the recent years, more effort is directed to the shallow pays as they often give considerable production contribution. This paper will cover habitat and identification of shallow pays on seismic data. Their traps and seals were examined and compared to the main pays. The source rock, kitchen and migration are interpreted to be somewhat similar. The reservoir characters are of high quality braided and meandering river sandstones. Seismic reservoir characterization and hydrocarbon indication in the shallow reservoirs are feasible due to their acoustic properties. Two types of trap are proven: structural and combined traps. Faulted anticline is the major structural trap. The combined trap is formed by confined channel complex, bounding faults and closing dip as in CFR-F block Upper PTO. Intra formational clays act as vertical seals while lateral seals are formed by faults. The vertical and lateral seal capacity is considered smaller compared to the thick Chumsaeng shale for the main Lan Krabu reservoirs. Seismic anomalies correspond to the proven shallow pays. The D block PTO oil accumulation is associated with bright spot and notable flat spot corresponds to the oil water contact. Nong Pluang Yom and CFR-F block PTO gas accumulations are identified as low frequency bright spot on seismic data. Seismic attribute was successfully utilized for reservoir characterization and well targeting in the CFR-F block Upper PTO oil accumulation. A mapped Lower PTO seismic anomaly in the northern flank was successfully tested by LKU-U06 well with 23 m of oil pay. LKU-U06 initial production rate from PTO was 2000 BOPD, represented about 10% of overall field daily production rate. These encourage the working team to put more effort to find and develop more shallow pays in the field. Introduction The Sirikit Main Field is located in Phitsanulok Basin, Central Plain, onshore Thailand, approximately 400 km north of Bangkok (Figure 1). The Field is located in the S1 concession, operated and wholly owned by PTT Exploration and Production. The Field was discovered in 1981 by drilling LKU-A01 well. Sirikit Main hydrocarbon accumulation is mainly found in the Miocene Lan Krabu formation K and L reservoir members with additional accumulation in the deeper and shallower reservoirs. Pre-Tertiary basement, Oligocene Sarabop - P formation and Lan Krabu M member are the deeper reservoirs. Lan Krabu K and L are estimated to hold more than 88% of Sirikit Main total hydrocarbon in place volume. Shallow hydrocarbon is trapped in the Lower Yom and Pratu Tao Formations sandstone reservoirs which in the past were rarely considered to be drilling target in the field. Pratu Tao reservoirs contribute around 3.2% of the field's in place hydrocarbon volume.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.