Effective reservoir management requires sound decision making that is based on formation evaluation data acquired during all stages of the life of the well. Without this data, reservoir understanding is compromised, which can impact long term well productivity. Given the increasing challenges of acquiring data in today's geometrically complex wells, new methods of data acquisition are constantly being developed and refined. This has led to a new area of oilfield innovation called conveyance. This paper is an analysis of the risks associated with the acquisition of formation evaluation data. These risks are generally classified as follows:Non Productive time due to the inability of logging tools getting to bottom. (bridging)Non Productive time due to delays associated with making last minute arrangements for alternative logging methods when bridging problems become too severe.Lost in hole charges associated with permanently sticking logging tools due to challenging hole conditions.Unsound decision making throughout the life of the well, because challenging hole conditions, made the acquisition of formation evaluation data impossible. The risks outlined above can also be assessed depending upon the data requirements and the conveyance method employed. A new risk assessment will be presented that discusses the risks associated with acquiring the data that provides insight into the six main formation properties required by the industry to understand reservoirs. Several conveyance techniques that assure the acquisition of data will be discussed along with case history's of some of these applications. This paper will serve as a means to understand and assess the risks associated with the acquisition of formation evaluation data. It will also increase awareness of the techniques that exist for acquiring data, and ultimately allow for developing the best strategy to acquire formation evaluation data. Introduction As global demand for hydrocarbon resources increases, so to have the challenges associated with determining their nature and location in the subsurface. Factors such as the exploitation of unconventional reservoirs, more development of carbonate reservoirs, and increasing the recovery factor, have increased the need for better understanding of formation properties. At the same time, new drilling technologies and strategies that allow for access to these reservoirs have created new challenges in the acquisition of formation evaluation data. In order to maximize the understanding of the reservoir, the following key formation properties must be determined to the highest level of accuracy possible:LithologyPorosity
Horizontal and multilateral wells are being drilled as a cost-effective approach to increasing production and adding reservoir value. The data acquisition strategy makes extensive use of formation pressure measurements that are critical to the understanding of the economic potential of a reservoir. Conventional formation testing techniques have proven inadequate for determining producibility and formation pressures in horizontal and highly deviated wells due to high costs and extreme operational risks. In this paper, a low-risk solution is described for obtaining early history formation pressures in these challenging borehole conditions using a very small sized formation tester combined with robust new operational planning, practices, and techniques. The Compact Repeat Formation Tester (MFT), of diameter approximately 2.4 inches, was deployed in memory mode and conveyed to test depth. Extensive operational planning and pre-job modelling was completed to allow for optimum data acquisition while minimizing total operation time. Well conditions prohibited the formation tester from providing real-time surface communication, the formation tester was programmed to accommodate as wide of range of test scenarios as possible. All tool data were stored in onboard memory for retrieval after the formation tester returned to surface. Twenty two pressure stations were attempted in two wells to a depth of 2250m under borehole conditions where information is usually not attainable. The data obtained from the stations was of good quality and the pressure results were subsequently confirmed by production. Several examples are presented to demonstrate this new technique was successful in obtaining pressure data of highest quality and confidence allowing reservoir insights that would otherwise have been unavailable. The ability to take pressures at multiple stations throughout the reservoirs has produced a detailed understanding of critical economic information. Additionally further developments allow very near time transmission of drawdown pressures back to surface to allow for instant analysis.
Traditionally, brown field developments have often required the plug-back and side-track of existing drain-holes, to target any nearby opportunities. With advances in drilling technology, there is a general preference to drill small diameter wells due to the comparative cost advantage of small holes. In the recent times, this preference has led some wireline service companies to start to offer open-hole formation evaluation services with slim tools having diameter in the 2.0 -to- 2.5 in range. At present, most of the traditional petrophysical measurements can be acquired utilizing slim tools. In addition, several "specialized" measurements such as cross dipole sonic, formation pressure testing, and resistivity imaging can also be acquired. The use of battery and memory technologies has allowed these tools to be deployed using a broader range of conveyance techniques allowing for reduced risk in the entry of slim wells. The provision of slim hole logging services has created an opportunity in the industry to leverage these tools for the economic development brown fields. Thus short horizontal sidetracks and well re-entry’s to test deeper horizons can be drilled and logged successfully. Saudi Aramco has been able to leverage these tools in its continued development of the giant Ghawar field. Some of the development projects are listed below; Some horizontal side-tracks with 3–7/8" hole sizes have been drilled under high dog-legs than was previously impossible and logged successfully.It is now possible to run well-completions in newly drilled wells that have well control problem. A provision is made to subsequently log these wells with slim wireline logging tools.It is now possible to run a complete suite of wireline logs across some old wells that were previously completed without a full formation evaluation logging suite.Slim-hole formation resistivity imaging services are now being provided, to aid in the identification of borehole break-out and fractures features that might affect the well’s productivity.Slim hole formation pressure testing have been acquired in slim wells in order to generate a pressure gradient, determine oil mobility, and define oil-water contacts Several case studies would be used in this paper to demonstrate how Saudi Aramco has leveraged these slim wireline tools to realize some development opportunities. Also examples would be used to show that these slim tools do not compromise the quality of log data acquisition.
This reference is for an abstract only. A full paper was not submitted for this conference. Abstract Effective reservoir management requires sound decision making that is based on formation evaluation data acquired during all stages of the life of the well. Without this data, reservoir understanding is compromised, which can impact long term well productivity. Given the increasing challenges of acquiring data in today's geometrically complex wells, new methods of data acquisition are constantly being developed and refined. This has led to a new area of oilfield innovation called conveyance. This paper is an analysis of the risks associated with the acquisition of formation evaluation data. These risks are generally classified as follows:Non Productive time due to the inability of logging tools getting to bottom. (bridging)Non Productive time due to delays associated with making last minute arrangements for alternative logging methods when bridging problems become too severe.Lost in hole charges associated with permanently sticking logging tools due to challenging hole conditions.Unsound decision making throughout the life of the well, because challenging hole conditions, made the acquisition of formation evaluation data impossible. The risks outlined above can also be assessed depending upon the data requirements and the conveyance method employed. A new risk assessment will be presented that discusses the risks associated with acquiring the data that provides insight into the six main formation properties required by the industry to understand reservoirs. Several conveyance techniques that assure the acquisition of data will be discussed along with case history's of some of these applications. This paper will serve as a means to understand and assess the risks associated with the acquisition of formation evaluation data. It will also increase awareness of the techniques that exist for acquiring data, and ultimately allow for developing the best strategy to acquire formation evaluation data.
Occurrences of deep gas are commonly found in clastic reservoir rocks. The great depths of these reservoir rocks often result in rocks with low porosity and poor permeability. In order for these reservoirs to be productive, natural fracture systems or induced fractures from stimulation processes are required to allow gas to flow to the well bore. In order to assess the potential of these reservoirs, explorationists around the world depend on data acquired from resistivity imaging tools to visualize the fractures. This paper will discuss fracture analysis using resistivity image data that provides better reservoir characterization on fractured reservoir than the normal open hole logs. Image data has higher resolution compared to the basic open hole data, and allows for fracture visualization down to 2mm. Petrophysical analysis using basic open hole data will average out the fine details of the fracture and its effects on porosity and permeability. Image based petrophysics known as "Image petrophysics" allows for the conversion of high resolution image data to high resolution petrophysical properties which provides greater understanding of the impact of the fractures on reservoir characterization. The use of Image data calibrated with either core data or basic open hole data allows for the derivation of high resolution porosity distribution. Permeability derivation can also be achieved using image data calibrated with core data. This process can also be extrapolated to wells that are un-cored. This paper will also discuss the challenges of acquiring image data from these deep environments by employing memory based image tools that can be conveyed using a broad range of conveyance techniques.
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