Ali, Hamza (Schlumberger) | Shah, Abdur Rahman (Schlumberger) | Akram, Agha Hassan (Schlumberger) | Khan, Waqar Ali (Schlumberger) | Siddiqui, Fareed Iqbal (Pakistan Petroleum Limited) | Waheed, Abdul (Pakistan Petroleum Limited) | Ahmed, Faizan (Pakistan Petroleum Limited)
A recent study addressed the modelling challenges of Alpha* gas condensate field. Alpha gas condensate field has a gas in-place of about 1 TCF, and both condensate and black oil production in addition. The field has been producing from two reservoirs SI and DI, for the past 26 years. Alpha field is subdivided into two segments called the Central Area and the Northern Area which are separated by a fault as shown in Figure 2. * Not its real name. One of the most unusual features of Alpha field are the'phase switch wells'.
Tight Gas Reservoirs (TGR) are one of the primary types of unconventional reservoirs to be exploited in the search for longlasting resources.TGR's are difficult to produce for a number of reasons. Due to their low productivity a thorough understanding is needed regarding the factors that affect gas production rate over the life of these reservoirs.
This paper is focused on analyzing the effects of drainage area, gas rate, fracture conductivity, porosity, and reservoir permeability on production performance. In particular, the impact of permeability, from ultra tight (0.0004 md) to tight (0.1 md) reservoirs, on drainage area and reserves is analyzed in detail.
A semi-analytical simulator is used in this study. A conceptual case study was performed comparing a hydraulically fractured vertical well with a multiple-fracture horizontal well in same reservoir. Fracture conductivity is estimated by using StimLAB proppant consortium correlations for different flow rates, which takes into account non-Darcy pressure drops and other factors.
The results of this work conclude that in ultra tight reservoirs, the drainage area is significantly reduced. Only the near fracture rock is drained, and a high density of wells and fractures is needed. This behavior changes with increase in reservoir permeability. In ultra-tight reservoirs, horizontal wells with multiple fracs may be the only viable option for commercial production. A general workflow is also described as to how forecasting in such reservoirs can be made more accurate.
Thailand's oil and gas industry has been successful in finding and recovering hydrocarbon reserves in the Gulf of Thailand since last three decades and have currently installed over 200 fixed offshore structures. Some of these installations are now reaching the end of their economic productive lives and will need to be decommissioned soon. There are complex issues in terms of legislation, environment, safety, costs, technical feasibility and public acceptability. This paper describes the issues relevant to decommissioning in Thailand and proposes appropriate decommissioning solutions developed over the past few years.
The proposed decommissioning solutions are intended to support Thailand's oil and gas industry and its regulators in ensuring compliance with international decommissioning guidelines, balancing economics, safety, practicality and technical feasibility of operations with the environmental benefits and also satisfying needs of the key decommissioning stakeholders in Thailand so as to achieve conflict-free process of decommissioning.
Technical aspects of offshore removal process primarily relates to the lifting of modules and sub-sea structural cutting methods. Lifting techniques range from conventional crane barges used in installation to specialized decommissioning vessels. Basically cost, technical feasibility and safety are major drivers in selection of appropriate lifting method. Sub-sea cutting include explosives and cold cutting techniques, for which cost and environment are the major decision making factors. Environmental aspects of decommissioning can be categorized into short term and long term. Short term environmental impacts are primarily related to the decommissioning methodology whereas the long term environmental impacts are related to the chosen disposal scenario i.e., final destination of each component of an offshore facility. Key recommendations regarding environmental solutions are in the form of Best Practicable Environmental Option (BPEO) framework, which helps determining balanced disposal scenario as well as suitable decommissioning methodology.
Increased energy demands have currently resulted in rapid growth of number of offshore installations in the Gulf of Thailand. At the same time, the old disused installations need to be timely and appropriately decommissioned, which is not possible without having acceptable decommissioning solutions in hand. Such solutions need to be in compliance with applicable international decommissioning guidelines while adopting best practical environmental option hence assuring conflict-free decommissioning process. Therefore, development of such decommissioning solution are significant in assuring "RESPONSIBLE PERFORMANCE: TO DO THE BEST WE CAN" in order to help attain sustainable benefits for further development of Thailand's oil and gas industry.
The Petroleum industry has brought enormous benefits to society. Petroleum reserves located under the seabed have resulted in the development of offshore structures (facilities) throughout the world. At the end of their economic production lives, these installations are required to be decommissioned to ensure safety of navigation and to protect the rights of other users of the sea. Offshore facilities decommissioning raises many complex issues in terms of environment, safety, technology and economics.
The industry has tried to develop and implement decommissioning strategies such that these issues are balanced. After 1995 the issue of decommissioning received global media attention with the successful disruption of plans to decommission the Brent Spar in the North Sea. This indicates the level of public interest and concern for the environment. The issue of public acceptability is therefore considered as an important factor in preparing decommissioning strategies. Currently, Thailand's oil and gas industry must face this challenge as some of the offshore installations in the Gulf of Thailand are reaching the end of their economic production lives.
Thailand oil and gas industry has been established for over 25 years and has been successful in finding and developing the natural resources that have helped the economic and social development of the Kingdom. Presently there are over two hundred fixed installations in the Gulf of Thailand and some of them are reaching the end of their economic production lives. The regulators are seriously taking up measures in order to develop guidelines that can ensure a balanced approach for decommissioning in terms of technical, environmental, legal and financial aspects of decommissioning. Thailand has previously encountered conflict situations in infrastructure projects and moreover, international disputes on decommissioning have emphasized the need of considering public opinion properly to avoid any conflict in decommissioning projects. Thailand industry regulators have a clear message to incorporate the public opinion into the decommissioning process. Therefore, efforts have been initiated for the development of decommissioning guidelines that can include the requirements of the stakeholders in order to avoid any subsequent conflicts in the oil and gas facilities decommissioning projects.