AspenTech Chosen to Optimize Production at Major Oil & Gas Field in Thailand; PTT Exploration and Production Implements Bongkot Optimization System Based on aspenONE(TM) Solution to Maximize Daily Production.

CAMBRIDGE, Mass. -- Aspen Technology, Inc. (NASDAQ: AZPN), the leading provider of software and services to the process industries, today announced that PTT Exploration and Production (PTTEP) has selected AspenTech to implement a system to optimize production from the largest natural gas field in Thailand. The integrated aspenONE(TM) solution, known as the Bongkot Optimization System, will be implemented by AspenTech's Professional Services group, and is expected to enable PTTEP to maximize daily production from the field.

The Bongkot Optimization System provides PTTEP with key functionalities including operations surveillance, production optimization, production planning and production allocation. Users access the system via web-based information portals. The integrated aspenONE solution is built on a number of industry-leading AspenTech applications that will enable PTTEP to model and optimize the complex Bongkot production network, including the Aspen HYSYS(R) and Aspen HYSYS Upstream(TM) simulation platforms, and the Aspen InfoPlus.21(R) real-time database.

The development of the Bongkot Optimization System is a result of a study conducted by AspenTech which revealed that significant benefits could be achieved in the Bongkot asset by using an integrated solution to manage and optimize production. The field is located in the Gulf of Thailand, and consists mainly of gas reservoirs and some oil reservoirs, with multiple wells drilled from 14 wellhead platforms. The reservoirs are multi-layered and multi-faulted, making production from the field difficult.

"The complex networks of reservoirs, wells, flowlines and processing facilities make off-shore production systems difficult to manage and optimize," said Blair Wheeler, Senior Vice President, AspenTech. "aspenONE solutions for the oil & gas industry provide improved visibility and understanding of operational performance, so that optimum operating strategies can be identified. By selecting AspenTech's Professional Services group to implement its new system, PTTEP will be able to benefit from the industry knowledge and experience of our team, and thus realize the maximum value from the solution."

The Bongkot project builds on the existing relationship between AspenTech and PTTEP, in which AspenTech is the simulation supplier to PTTEP. The company has used Aspen HYSYS for over six years, primarily for modeling on-shore facilities.

License revenue from this transaction was recognized in AspenTech's fiscal quarter ending March 31, 2006.

About PTTEP

PTT Exploration and Production Public Company Limited (PTTEP) was established in 1985 by the Petroleum Authority of Thailand to explore, develop, and produce Thailand's petroleum reserves to maximize the country's benefit from energy resources. Following significant expansion of PTTEP's business operations both domestically and internationally, it registered as a public company in 1992. At present, PTTEP has a registered capital of Baht 3,322 million. Besides its core business of petroleum exploration and production, PTTEP has extended its investments into strategic downstream projects, and has also entered the power generation sector to enhance and sustain its core business. For additional information about PTTEP, please visit www.pttep.com.

About AspenTech

Aspen Technology, Inc. provides industry-leading software and professional services that help process companies improve efficiency and profitability by enabling them to model, manage and control their operations. AspenTech's integrated aspenONE(TM) solutions are aligned with the key industry business processes, providing manufacturers the capabilities they need to optimize operational performance, make real-time decisions and synchronize the plant and supply chain. Over 1,500 leading companies already rely on AspenTech's software, including Bayer, BASF, BP, Chevron Corporation, DuPont, ExxonMobil, Fluor, GlaxoSmithKline, Sanofi-Aventis, Shell, and Total. For more information, visit www.aspentech.com.

This press release may contain forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Actual results may vary significantly from AspenTech's expectations based on a number of risks and uncertainties, including, without limitation: AspenTech's plan to improve operational performance may not be implemented effectively; AspenTech has identified material weaknesses in its internal controls with respect to software license revenue recognition and other matters, that, if not remedied effectively, could result in material misstatements; risks around securities litigation and investigations; AspenTech's lengthy sales cycle makes it difficult to predict quarterly operating results; fluctuations in AspenTech's quarterly operating results; AspenTech's dependence on customers in the cyclical chemicals, petrochemicals and petroleum industries; the possibility of new accounting standards or the interpretation of existing accounting standards affecting our financial results; AspenTech's ability to raise additional capital as required; intense competition; AspenTech's need to develop and market products successfully; reliance on relationships with strategic partners; challenges associated with international operations; and other risk factors described from time to time in AspenTech's periodic reports filed with the Securities and Exchange Commission. AspenTech cannot guarantee any future results, levels of activity, performance, or achievements. AspenTech expressly disclaims any current intention to update forward-looking statements after the date of this press release.

AspenTech, aspenONE, Aspen HYSYS, Aspen HYSYS Upstream, Aspen InfoPlus.21 and the aspen leaf logo are trademarks of Aspen Technology, Inc., Cambridge, Mass.