Africa (Sub-Sahara) Kosmos Energy has made a significant deepwater gas discovery off Senegal. The Guembeul-1 well in the northern part of the St. Louis Offshore Profond license in 8,858 ft of water encountered 331 net ft of gas pay in two excellent-quality reservoirs, the company reported. The results demonstrate reservoir continuity and static pressure communication with the Tortue-1 well, which suggests a single gas accumulation. The mean gross resource estimate for the Greater Tortue complex has risen to 17 Tcf from 14 Tcf as a result of the Guembeul discovery, the company said. Kosmos, the operator, has a 60% interest in the well. Timis (30%) and Petrosen (10%) hold the remaining interest. In Salah Gas has started production from its Southern fields in Algeria.
Guo, Shusheng (CNOOC Ltd_Zhanjiang) | Gao, Yongde (CNOOC Ltd_Zhanjiang) | Gui, Feng (Baker Hughes, a GE Company) | Wang, Shanshan (Baker Hughes, a GE Company) | Bordoloi, Sanjeev (Baker Hughes, a GE Company) | Ong, See Hong (Baker Hughes, a GE Company) | Du, Chao (CNOOC Ltd_Zhanjiang) | Wang, Shiyue (CNOOC Ltd_Zhanjiang)
The drilling in Wushi Sag of the Beibu Gulf appears to be problematic with frequent pack-off, tight-hole and stuck-pipe events as well as kicks and losses occurring in different wells. It is of great importance to find out the main cause or causes of these problems so that proper methods and techniques can be utilized to mitigate the problems and reduce the drilling non-productive time (NPT).
A series of drilled wells were reviewed to identify the key wells to be used for the geomechanical modelling and to help with understanding the drilling problems. One of the outcomes of the detailed geomechanical analysis was the realization that the stresses and rock behaviors are mainly affected and controlled by the structures. Wushi Sag can be divided into four structural areas: subsag-steep slope in the south, central inverted structure area, north slope and strike-slip faulting belt in the west. As a consequence of the complex structures, the formation depth varies greatly while some formations are absent or incomplete in some wells due to the well-developed high-angled faults.
An outcome of the study was the understanding that formation pressures are different in every structural area and are controlled by structural location and burial depth. The main overpressure generating mechanism was found to be type-II fluid expansion caused by either hydrocarbon generation or thermal effects, which can be well correlated to the oil window threshold in the area. Under-compaction may also play a role in some cases, but the overpressure caused by this mechanism is usually low in magnitude. Rock properties vary across the Sag while wells are hard to correlate with each other in different structural areas. The stress conditions appear to be different in each area although the main stress regime is strike-slip with the strike-slip faulting belt in the west having the highest stress ratio.
Due to the complexity of the pressure distribution, lateral formation changes and different stress conditions, improper mud weights and casing designs were used in some earlier wells, which likely led to the types of drilling problems listed above. Wells with severe instability problems were generally drilled with lower mud weights compared to the wells with lesser problems. Wells with both pack-off/tight holes and fluid losses usually have surface or intermittent casing shoes set too shallow while not preparing for the steep pressure ramp in deeper formations. Based on the problem diagnostics and geomechanical analyses, recommendations were made to help with the drilling of future wells by mitigating drilling-related instability problems. A series of wells were drilled successfully following the recommendations with all the possible risks properly understood and mitigated.
Zhenghe, Yan (CNOOC) | Xiaofei, Gao (CNOOC) | Yong, Yang (CNOOC) | Zhihua, Rao (CNOOC) | Donghong, Luo (CNOOC) | Azwar, Olivia (Schlumberger) | Chao, Wang (Schlumberger) | Halomoan, Parlindungan Monris (Schlumberger) | Bisain, Amarjit Singh (Schlumberger)
After more than 20 years of intensive production in XiJiang oil field, a sand group that consists of multiple reservoirs with a thin oil column of less than 4 m and with strong bottom water drive has been revisited. Some assessments were made previously, including drilling horizontal wells with average recovery factor or only 2.3%. In early 2013, new horizontal well drilling was initiated to reassess these reservoirs with a different approach. The objectives were to optimize the standoff between the lateral and the oil/water contact, which is very critical to well performance, by placing the lateral as close as possible to the reservoir top and to evenly regulate the downhole flow across the draining lateral. The program was successful in reassessing the development reservoirs in the mature oil field that had previously been considered to be uneconomic through a reentry horizontal well drilling program and the implementation of the best practices in operations. The operational practices included the precise landing and lateral placement of horizontal wells and the use of inflow control devices (ICD) for completion. Logging-while-drilling (LWD) bed-boundary mapping, with the ability to map multiple key boundaries, including fluid contact for precise well placement, was integrated with multifunction formation evaluation LWD, which provides real-time formation evaluation to optimize the ICD design for completion.
The globalization of business, combined with the necessary localization of staff, is driving a growing diversity in the workforce make-up of multi-national organizations. This, in turn, drives the necessity to improve organizational skills and processes for better communication and buy-in to gain and maintain alignment of these diverse groups. Alignment is a critical factor to organizational efficiency and performance. Attaining a "one-culture?? consensus of attitude, rules and business values for the organization is essential, as a starting point, to lay the proper foundation to establish the strategic plan, from vision to business imperatives, goals and objectives.
This growingly diverse workforce mix represents an opportunity and a risk, to either harness cultural diversity as a strength, or to accept it as an inherent weakness to be constantly mitigated. Not to meet this multi-cultural challenge head-on represents a significant risk of organizational functionality, potentially resulting in loss of focus, direction and subsequently performance. However, meeting this challenge in a positive and pro-active way can empower and harness a collective of international and local knowledge, energy and skills that make anything possible.
This paper addresses often ignored or hidden multi-cultural problems and some root causes through three O&G organizations case studies. Also addressed are methodologies used to overcome the multi-cultural challenges and turning a grass-roots strategic planning process into a positive communication and alignment tool. These organizations reinvented and realigned themselves through this systematic process, both internally and with all stakeholders, achieving breakthrough performance.
This paper is intended to be a help to companies and leaders embarking on a new country entry organization or re-energizing flagging multi-cultural organizations. While not a definitive or comprehensive investigation of the subject, one of the main objectives of the paper is to bring these challenges to light and open the subject for further attention and development.
Asset based functioning in companies has been setting examples of fast track development strategy by combining multi discipline functions. This is especially relevant for development of a marginal field located adjacent to a large gas field, hydro dynamically connected at aquifer level. In the case history of Vasai East field, these aspects are presented here.
3-D seismic carried out in the year 2000 around the existing field provided a lead for possibility of a new structure towards east. The first exploratory well drilled in March 2001 led to discovery of new marginal field Vasai East having oil overlain by large sour gas cap and underlain by large aquifer. The field was delineated by mid 2002 after drilling of four additional exploratory wells. It was also concluded that Vasai East field is separated from main Vasai gas field at hydrocarbon level, but is hydro-dynamically connected through a common aquifer resulting in sub-hydrostatic pressures. Immediately after delineation, fast track development strategy was formulated and a core team was constituted by combining functions of geology, geophysics, reservoir, drilling & well engineering, asset, design and engineering and R&D institutes to workout development plans for the field.
This paper discusses the combined results of a multidisciplinary team for fast track development, technological options, economization of new infrastructures, techno-economic evaluation of different development options. The cost effective development plan with investment of about US$ 200 million was approved by management in shortest possible time for this marginal field.
Since adjoining gas field was being produced at its peak rate, any delay in implementation of this fast track strategy could lead to serious impact of oil recovery of this field. The implementation of this development plan is on fast track execution.
Jin, Zhijun (Basin & Reservoir Research Center, University of Petroleum, Changping, Beijing, China 102249) | Bai, Guoping (Basin & Reservoir Research Center, University of Petroleum, Changping, Beijing, China 102249) | Ding, Wenlong (Qinghuangdao Campus, Daqing Petroleum Institute, Qinghuangdao, Hebei, China 066000)
STRIKE SLIP FAULT SYSTEMS AND ASSOCIATED SEDIMENTARY BASINS IN CHINA Zhijun Jin, Basin & Reservoir Research Center, University of Petroleum, Changping, Beijing, China 102249 Guoping Bai Wenlong Ding Qinghuangdao Campus, Daqing Petroleum Institute, Qinghuangdao, Hebei, China 066000 Introduction The China Plate was affected by the NW-NWW subduction of the Pacific Plate since Mesozoic time and then influenced by the collision of the Indian Plate with the Euroasian Plate, which initiated from Eocene time. The interactions of the three plates led to the formation and development of three main strike slip fault systems in China: the Tanlu in the east, Aerjin in the northwest and Sanjiang in the southwest. This study will discuss the salient features of the three strike slip fault systems and the associated sedimentary basins and will also recommend exploration strategies for basins with different degrees of exploration maturity. Aerjin Strike Slip This system constitutes the northwestern boundary of the Qinghai-Tibet plateau. It separates the Fault System Tarim Basin from the Chaidam Basin. With a length of up to 3500 km, it affected an area of about 500,000 km2 and controlled the formation and development of 11 basins. The major strike slip movement of the fault system occurred during Tertiary time. As a result, basins associated with it include both Tertiary strike slip fault basins and deformed Mesozoic strike slip fault basins. The 11 basins associated vary greatly in terms of petroleum endowment. The difference is attributed to the varying factors of petroleum charge, trap and timing in these basins. The key exploration breakthroughs in these basins lie with better understanding of the regional tectonics and depositional history. Tanlu Strike-Slip This system affected the evolution and hydrocarbon generation, migration and accumulation of the Fault System important petroliferous Meso-Cenozoic basins in east China, which include the Songliao, Bohai Bay, and Subei-South Yellow Sea Basins. These basins lie adjacent to the fault system. Within the Tanlu fault zone, a series of grabens such as Yishu and Yilan-Yitong have also developed. The controls of the fault system on the basin development varied with time. It had little impact on the development of Early-Middle Jurassic basins in east China. These basins generally trend E-W and then SW-NE or NNE-SSW closer to the fault system. Their development was largely controlled by the E-W trending paleo-tectonic structures resulting from Indocynian orogeny during a slightly extensional stress environment. The Early-Middle Jurassic faulted basins tend to be small in scale and are highly separated from one another. There is little exploration in these basins. However, dark mudstones of deep lake origin have been proven to be well developed in some of these basins. Available geochemical data indicate that they are moderate to good, mature to high mature oil source rocks. Their source rock potential is further
This paper was prepared for presentation at the 1999 SPE Asia Pacific Oiland Gas Conference and Exhibition held in Jakarta, Indonesia, 20-22 April1999.
The simple development engineering project of W10-3 North (W10-3 N) oil field has its own significance in the history of the simple oil field development for China's offshore oil industry and is a crystal of research fruits on early production system" in the offshore engineering field of China. This article introduces the development of the marginal oil fields and the conversions of the two production platforms from drilling rigs and their engineering features. It provides necessary and referable information for understanding the cases of the simple development engineering for marginal oil field in Beibu Gulf and the conversions of jack-up rigs "Nai Hia No. 1" (NH1) and "Bo Hai No. 6" (BH6) to double purpose of drilling and production rigs.
Key words: marginal oil field, simple development engineering
1. ENGINEERING BACKGROUND AND OUTLINES
1.1 W10-3 N DEVELOPING ENGINEERING
More than 10 fault block oil fields of small and middle sizes have been discovered consecutively in the basin of Beibu Gulf by self and joint explorations with foreign companies. W10-3 oil field cooperatively developed by China Offshore Oil Nan Hai West Corporation (CONHW) and TOTAL was put into production commercially in 1986. One wellhead platform and one complete set of floating production system have been constructed on the oil field, whose facilities include a fix tower Single Point Mooring (SPM) and a Floating, Processing Storage, Off - loading (FPSO) tanker (see Fig. 1).
Desheng, Li (Research Institute of Petroleum Exploration and Development, P R China) | Jianyi, Hu (Research Institute of Petroleum Exploration and Development, P R China) | Xiaoguang, Tong (Research Institute of Petroleum Exploration and Development, P R China) | Shubao, Xu (Research Institute of Petroleum Exploration and Development, P R China) | Guonong, Hu (Research Institute of Petroleum Exploration and Development, P R China)
INTRACRATONIC BASINS OF CHINA AND THEIR HYDROCARBON ACCUMULATIONS Li Desheng, Hu Jianyi, Tong Xiaoguang, Xu Shubao and Hu Guonong, Research Institute of Petroleum Exploration and Development, PR China. Abstract. The Tarim Basin of Northwest China is one of the largest and least explored inland basins of the world. This paper summarizes the geological history and hydrocarbon potential of the Chinese intracratonic basins, using the Bohai Gulf Basin as an example of an extensional basin in East China, the Sichuan Basin as a `transitional type' basin in Central China, and emphasizing the frontier Tarim Basin of Northwest China, a compressional type basin. In the Bohai Gulf Basin hydrocarbon accumulations are usually related to paleogene grabens or half-grabens. Although this is one of the main producing areas of China, prospects are bright for new oil and gas discoveries. The Sichuan transitional basin `is affected by both the trans-Eurasian Tethys tectonism and that of the circum-Pacific. It is the most important gas producer in China. The Tarim Basin of Northwest China is one of those created by the northward impact of the Indian Plate. Including Paleozoic outcrops around its rim, it is almost 700 O00 sq km in size. In its centre is the 324 O00 sq km. Taklimakan Desert. A few discoveries have been made in Paleozoic, Jurassic and Tertiary rocks. Large potential traps exist, so significant exploration success is anticipated. Résumé. Le bassin de Tarim, au nord-ouest de la Chine, compte parmi les plus grands et aussi les moins explorés des bassins continentaux du monde. Cette communication résume l'histoire géologique et le potentiel en hydrocarbures des bassins intracratoniques chinois. Le bassin du golfe de Bohal est utilisé comme exemple d'un bassin extensionnel en Chine orientale, le bassin de Sichuan comme un bassin de type `transitionnel' en Chine centrale, et surtout le bassin de Tarim, au nord-ouest de la Chine, comme un bassin de compression. Dans le bassin du golfe de Bohai, les accumulations d`hydrocarbures sont associées à des grabens ou demi-grabens d'âge paléogène. Bien que cette région soit une des plus productrices de la Chine, les possibilités de nouvelles découvertes de pétrole et de gaz naturel sont bonnes. Le bassin `transitionnel' de Sichuan a été affecté par les évènements tectoniques téthysiens trans-européens et par ceux du domaine Pacifique. C'est la région chinoise la plus productrice de gaz naturel. Au nord-ouest de la Chine, le bassin de Tarim a été créé par la collision, vers le nord, de la plaque indienne. Avec les affleurements paléozoïques de sa marge, ce bassin mesure près de 700 O00 km2 avec, en son centre, le désert de Taklimakan de 324 O00 km2 de superficie. Quelques découvertes ont été faites dans des roches paléozoïques, jurassiques, et tertiaires. Des pièges de grandes dimensions sont présents, laissant présager de grands succès en exploration.
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