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Abstract Almost every drilling operation is a potential source of damage to well productivity, lost circulation, differential sticking and other related conventional Drilling problems. This paper re-visits the key damage mechanisims and provides a broad overview on how they occur during various oilfield operations, and their effect on well productivity. Also, lost circulation or fluid invasion potential in high permeability zones, large open fractures, heterogeneous carbonates with massive interconnected vugular porosity, or pressure depleted zones would be a major issue of concern during conventional drilling condition. The worst-case scenario would be a combination of one of these high permeability features with significant pressure depletion. In order to overcome the above problems while drilling, the industry developed a method to drill with a bottom hole pressure below the pore pressure, called Underbalanced Drilling - UBD As the majority of hydrocarbons being exploited today are found in existing pressure depleted or complex and lower quality Reservoirs with lots of the conventional drilling problems, this is where Underbalanced Drilling Technology can add value and in some cases reduce development cost. Soon, Underbalanced Drilling will become the standard field development technique, both Onshore and offshore, where the Geology and Reservoir are suitable. The paper reviews several case histories and real results highlighting the advantages of Underbalanced Drilling Technology in reducing Formation Damage, Lost Circulations and improving well productivity. Introduction The Oil and Gas Industry drills thousands of wells worldwide each year. From the Reservoir and Production Engineers perceptions, a successful well is one that achieves its maximum production potential with no, or minimal, formation damage. Unfortunately, this objective is rarely achieved when conventional overbalanced drilling is used where mud solids and mud filtrate invade the reservoir formation and impair the permeability around the well bore. Formation damage can occur during almost any stage of petroleum exploration and production operations. This paper describes in detail the main formation damage mechanisms that occur during conventional drilling operation and how it can be controlled and prevented using Underbalanced drilling technology. The severity of solids and filtrate invasion depends on mud rheology, the duration of exposure to mud system, over-balanced mud pressure, rock permeability, and mineralogical composition of reservoir rocks. The solids and filtrate invasion causes the so called "skin effect" which may be attributed to different damage mechanisms that can have significant impact on the production and/or injection rates. Therefore understanding the different mechanisms of formation damage is becoming an important task for reservoir engineers in the oil and gas industry, because it is the first step to be taken to prevent and further alleviate this problem. What is Formation Damage? Formation Damage was once defined as: "the impairment of the invisible, by the inevitable and uncontrollable, resulting in an indeterminate reduction of the un-quantifiable". Luckily, the fact that Formation Damage is inevitable and Uncontroll-able has been replaced by a more positive attitude: Underbalanced Drilling Technology
- Europe > Norway > Norwegian Sea (0.35)
- North America > United States > Louisiana (0.34)
- Geology > Mineral (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.47)
Abstract Projects are now being procured or considered in bundles rather than on an individual, stand-alone basis. For the purpose of financial analysis, bundled projects can be considered as portfolios of projects. When projects are considered individually, some may be commercially viable as stand-alone projects and others may not. However, when projects are bundled together, an overall portfolio of projects may meet the promoters Minimum Acceptable Rate of Return (MARR) and be deemed commercially viable. This paper describes the mechanism and software used to assess a portfolio of small oil and gas projects, those being new projects and the refurbishment and operation of existing facilities. This paper describes how a non-commercially-viable batch of refurbished facilities can be financed with the help of cross collaterisation from the commercially viable batch of new projects when considered as a portfolio. Introduction Analysing projects on a project-by-project basis is a relatively simple operation. Many software programs exist which can accommodate the financial appraisal in terms of economic parameters and carry out sensitivity and risk analysis, using Monte Carlo simulation. More recently projects are now being procured or considered in bundles rather than individual stand-alone projects (Frank and Merna, [2003]). The financial analysis of these bundled projects can be considered as a portfolio of projects. Each individual project will have different cost and revenue implications and be subjected to different risk scenarios. When projects are considered individually some may be commercially viable as stand-alone projects and others may not be commercially viable on a stand-alone basis. However, when the projects are bundled together the overall portfolio of projects may meet a Promoters MARR and be deemed commercially viable. Merna and Smith (1999) suggest that when projects are undertaken as commercially viable projects utilising project finance they should โpiggybackโ non-commercially viable projects to ensure such projects are sanctioned. These non-commercially viable projects can, however, be financed by cross collateralisation of funds to make them viable as part of a portfolio of projects. Traditionally the commercial viability of a portfolio of projects has been assessed on the correlations between returns when calculating the portfolio standard deviation (Cuthbertson & Nitzsche [2001]) or on a project-by-project basis. The author, however, has developed a financial risk mechanism to provide economic parameters based on risk ranges for a portfolio of projects by combining an existing software program Computer Aided Simulation for Project Appraisal and Review, CASPAR (Merna & Khu [2003]) with spreadsheets. The outputs from the program and spreadsheets indicate the economic parameters of the base case, worst case and best case scenarios of the portfolio of projects in terms of economic parameters illustrated by cumulative cash flows as one project. Bundling Projects Bundling is the grouping of projects or services within one managed project structure in a manner which enables the group to be financed as a single entity. The key benefits are that this allows small projects to be financed by increasing the overall debt within the bundle to an economic level and allows various projects to cross collateralise each other. Key issues are that cash flows from single projects are robust (a single cash flow is often preferred). Smaller bundles can be created in the form of batches of projects. Batches of projects can be combined to create bundles of projects or portfolios. Capital market funding will often tend to concentrate on larger projects and is therefore not available as an option for smaller projects. Smaller projects will be seen as less effective as they do not benefit from economies of scale. The transaction costs on projects with a capital value of less than $10 million can be disproportionately high and severely affect returns and value for money (VFM).
- Energy > Oil & Gas > Upstream (1.00)
- Banking & Finance (1.00)
Abstract The paper presents an integrated model for Quality and Performance Improvement (Q&PI) Framework that has been established within ADCO (Abu Dhabi Company for Onshore Oil Operations) Petroleum Development Division (PDD) to ensure a continuous improvement in core activities. It highlights triggers and challenges which were behind the serious need for an integrated business model that will help the division in clarifying its vision in line with ADCO Business Strategy, and translate that vision into a set of business operational and measurable objectives. The achievements of Q&PI Framework in unifying and integrating all the divisional business units around a common understanding of business key strategic drivers are presented. The critical business objectives that can be continuously assessed and upgraded toward achieving the business vision with minimum business/technical uncertainties are exemplified, indicating a significant improvement in a typical E & P environment. Introduction PDD is a key division in ADCO with approximately 400 employees, mostly professional engineers and graduates in different disciplines. The major functions are to oversee Exploration and Full Fields Development of onshore fields in Emirate of Abu Dhabi, including a vibrant integration of surface and subsurface activities. In 2004 alone, the company plans to drill in excess of 100 wells and at the same time ensure efficient operations, maintaining the integrity of assets and shareholder's off take requirements at all times. The main driver of introducing the Q&PI Framework in PDD is to ensure and oversee the translation of PDD strategy into a quality and performance improvement system that supports effective optimization of the organizational assets to achieve the business goals. A framework that will create value from managing knowledge-based strategies that deploy the intangible assets within the organization, such as, employee potentialities and skills, customer relationship, shareholders guidelines, strategies, business processes, information technologies, database and management actions. A single model for developing an effective business strategy and ensuring continuous assessment of organization strengths to focus on areas for improvement is not sufficient for an important technical division such as the PDD. This is due to the high level of challenges that the division has to manage in order to reach the Shareholders expectation, which require an effective management system for business's planning and control. The business challenges encouraged the organization to establish a business framework that will give the division opportunity to become a strategy-focused organization. The Q&PI Framework developed consists of five key components. The first component is setting a strategic framework encapsulating the divisional strategy map, which integrates main objectives of all business units and business improvement, including short and long term plans. The second component is developing the value chain of divisional critical processes, which will give procedures and guidelines in what and how business can be effectively done to achieve the set objectives. The third component is to establish an implementation strategy to ensure a smooth transmission of critical process's development phase to the "live" implementation phase through sufficient awareness, training and communication programs. The fourth component is establishing a performance monitoring system to measure the actual performance versus identified targets. The fourth component is regarded as precursor to the fifth component "quality assurance review procedures" in which the variation reported in the measurement phase is to be analyzed and reported to management to take preventive or corrective actions for improvement. The PDD Q&PI Framework that covers the five business components were implemented in 2001, as "Set-Develop-Implement-Measure-Improve" cycle, ensuring the continuous assessment of strategy and critical processes to reach the desired excellence.
Abstract Computer systems used to capture and retrieve knowledge that can be made available in digital format can only contain a fraction of the corporate knowledge. In implementing Knowledge Sharing the computer systems are complemented by Knowledge Sharing communities in which people share what they know and what they need to know. Forming knowledge sharing communities locally is a practice that has many advantages but is more often than not limited to a small pool of colleagues with similar interests. Knowledge sharing through large virtual "communities of practice" makes available the practical and theoretical knowledge of many experienced professionals who need not sit in the same office, building or site. Modern communications technology and software can make this wider knowledge sharing an easy and low-cost reality. Putting the knowledge of a larger community of professionals to use via a community network will benefit the business and reduce costs. Approaches taken and value measurements will be presented. For the participants the knowledge sharing communities act as an on-site aid to continuous learning for professionals. This leads to new concepts for Knowledge Sharing and for Learning: WorkPLACE Learning. Introduction Nobody in the organization knows what the total organization knows. But there is no doubt that those organisations that are closer to enabling their staff to work on the basis of what the organization knows instead of on the basis of what the individual knows have a considerably higher earning power. This is also reflected in the Shell Exploration and Production (EP) Technical Function Management Framework: "Competitiveness in the EP industry depends to a large extent on the know-how and experience of companies and their staff. Sharing of information/knowledge across the EP Business is key to our success...". Sharing of information/knowledge spontaneously takes place within the context of individuals working in the same project, and individuals working within close proximity. The amount of information/knowledge being shared steeply declines when the distance between individuals exceeds 10 meters. Furthermore individuals may solicit advice from "people they know". The combination of (1) people working within close proximity, (2) the people working within the same project or organizational unit and (3) the people known by an individual represent the "individual network". As shown in figure 1 the combination of individual knowledge and individual network only reflects a small portion of "what we know as a company", which leaves us with the challenge how an individual can be given access to what the organization knows as a whole. Explicit Knowledge - Storing Knowledge on Computer Systems Information Technology provides mechanisms to provide access to "what we know as a company" by writing this knowledge down, and storing it in computer systems. In this section a technical view and a human view on this approach will be presented, leading to the conclusion that we will have to balance the technical and human perspectives to storing knowledge on computer systems.
- Asia (0.46)
- North America (0.46)
- Europe (0.28)
- Information Technology > Knowledge Management (1.00)
- Information Technology > Communications > Collaboration (1.00)
Abstract In this paper, the historical review for the drilling troubles encountered in the Nahr Umr (N.Umr) shale formation and the rock mechanics approach to improve the wellbore stability are described. An integrated approach is adopted for this study including the historical review for the actual drilling practices implemented to date, the studies of geomechanics, rock mechanics and chemistry for the N. Umr shale formation. The historical review is performed based on the actual drilling data from year 1991 to March 2004. The geomechanics model is determined with the data from the N. Umr shale formation and adjacent reservoirs. Logging data and collected formation sample data i.e. cores, cuttings are utilized to measure the properties of the formation. Numerical models considering the anisotropy and poroelastic nature of the shale lead the quantification of the failure mechanism. Laboratory testings are conducted to analyze the basic chemical properties of the shale, and the interaction between the shale and mud. A newly produced testing apparatus is applied to determine the shear strength change of the shale under saturated condition with mud. Scanning Electron Microscope is utilized to ensure the failure mechanism and evaluate the validity of the shale inhibitors. In this paper, the outline of the approaches is shown with some details of the testing and analysis methods. Introduction Recently, interests on the wellbore stability have been raised also in Gulf region, and several studies with newly developed ideas have been carried out. Especially, the instability problem of the N.Umr shale is a common concern in the southern part of Gulf region. Zakum Development Company (ZADCO) operates an offshore field, Upper Zakum (UZ) field. The shale instability problem in N.Umr formation is the major drilling problem in UZ field. The shale instability problem makes bottom hole condition worse, and sometimes leads to well sidetracking which force us spending additional expenses. Due to the frequent occurrences of the shale instability problem, ZADCO, Japan Oil Development Company (JODCO) and Japan Oil, Gas and Metals National Corporation (JOGMEC) commenced "Joint Study for N. Umr Shale Instability in Upper Zakum Field" in September 2000 with full support from Abu Dhabi National Oil Company (ADNOC). Intensive data acquisitions for N.Umr such as open hole logging and coring were performed with the corporation of Abu Dhabi Marine Operating Company (ADMA-OPCO), and the data were delivered to JOGMEC Technology Research Center (TRC) for stress analysis to develop a geo-mechanical model. The nature of the formation and root cause of the troubles have been studied and discussed in the previous papers. Although linear elastic and homogeneous modeling of the wellbore stability has succeeded to describe the instability phenomena, the authors have found that the N.Umr shale instability problem in UZ field occurs not through such simplified mechanisms. This paper has been prepared based on the findings obtained from the historical review for drilling operation through N.Umr in UZ field made by ZADCO and a laboratory study for the rock mechanics of N.Umr shale conducted by JODCO/JOGMEC.
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > Japan Government (0.95)
- Government > Regional Government > Asia Government > Middle East Government > UAE Government (0.54)
- Asia > Middle East > UAE > Abu Dhabi > Arabian Gulf > Rub' al Khali Basin > Zakum Concession > Zakum Field > Upper Zakum Field > Thamama Group Formation (0.99)
- Asia > Middle East > UAE > Abu Dhabi > Arabian Gulf > Rub' al Khali Basin > Zakum Concession > Zakum Field > Thamama Group Formation (0.99)
- Asia > Middle East > UAE > Abu Dhabi > Arabian Gulf > Rub' al Khali Basin > Abu Al Bukhoosh Field > Arab Formation (0.99)
- (2 more...)
Abstract This paper discusses the problem of the displacement of oil, saturating the fractured reservoir, by another fluid miscible with it in all ratios, in a gravity field. The equations are derived with allowance for all three mechanisms of mass transfer between fracture and matrix. Utilizing the method of characteristics provides the analytical solutions of the resulting system of equations. The results have been compared with experimental results. There is a very good agreement between the results and experiments. Intoduction Iran is one of the world's leading energy producing countries with an estimated 9 percent of the world's remaining recoverable oil reserves and 17 percent of its natural gas reserves. Almost 90 percent of Iranian petroleum reservoirs are carbonated and these carbonated reservoirs are generally tight, and flow conditions for oil in the matrix are poor. Therefore, the time needed to produce the oil will be longer than for high permeable sandstone reservoirs. Iranian carbonate reservoirs are fractured and consist of tight matrix blocks with fractures in between. The recovery factor for the Iranian fractured reservoirs is estimated to be in the range of 20 to 30 percent. In these reservoirs, the block heights are of the order of 3 to 15 m. The greatest percentage of Iranian oil reserves occurs in a number of fields lying along the southwest flank of the Zagros mountain chain, occupying a belt of gently folded en-echelon anticlines running parallel to the main mountains. The main reservoirs of southwest Iran occur in the extensively fractured carbonate rocks of the Tertiary Asmari formation, with other accumulations in older Cretaceous horizons within the Bangestan group. The Asmari is of Oligocene/Miocene age, comprising some 300โ370m of locally dolomitic, shallow water, neritic limestones which (apart from some sandstones) developed in the southwest of the basin and with a fairly uniform lithology over wide areas. This unconformably overlies marls and marly limestones of the Pabdeh formation, and is capped by the conformable anhydrites and limestones of the Gachsaran formation. The primary porosity ranges from 5โ25%, with a very low matrix permeability seldom exceeding 2 md. This would, at first glance, appear to preclude the Asmari as reservoir potential; however, the Asmari is so extensively fractured that permeabilities may commonly exceed 5 Darcys. Iran has been producing oil since the beginning of last century. The producing rate peaked at 6 million barrels per day in the late 1970's and has recently fallen to 3.2 million barrels per day. Without further investments and drilling of new wells it is estimated that the producing capacity of existing fields, will decrease with 8โ9 percent per year. Thus the gap must be filled by operational optimization such as drilling new wells, and various EOR processes in producing fields, in addition to exploration for new fields and development of discovered fields. Fractured reservoirs have always been considered poor candidates for enhanced oil recovery. This is mainly due to the complexities involved in predicting performance in such reservoirs. Miscible gas injection is a method that may significantly increase the oil recovery factor from Iranian fields, provided that gas is available (Iran have the second largest gas reserves in the world) and that such projects are economically viable. The declining oil production from Iranian fractured reservoirs after several decades of exploitation and the significant amount of oil still remaining in place are of great concern to the Iranian oil company and fully justify its interest in EOR processes. One of the important mechanisms in EOR from fractured reservoirs is miscible fluid injection. Miscible fluid injection allows recovering substantial quantities of that oil trapped in the matrix.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.74)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock > Limestone (0.65)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Reservoir Description and Dynamics > Reserves Evaluation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)