Methods for Real-Time and High-Resolution Formation Evaluation and Formation
Testing of Thinly Bedded Reservoirs in Exploration Wells

Claverie, Michel; Aboel-Abbas, Sabry; Harfoushian, Hagop Jack; Hansen, S. M.; Leech, Richard

doi:10.2523/101126-ms

“…This tool is also superior to a single probe tool in laminated, fractured, and unconsolidated formations [5][6][7] due to its larger inflow area. This module provides two inflatable packer elements for straddling a section of a reservoir from 3 to 12 feet, primarily to test and capture fluid samples from the selected interval.…”

Section: Introductionmentioning

confidence: 99%

Mini-DST Applications for Shell Deepwater Malaysia

Daungkaew

¹

,

Harfoushian

²

,

Cheong

³

et al. 2007

Proceedings of Asia Pacific Oil and Gas Conference and Exhibition

7

0

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fax 01-972-952-9435. AbstractExploration and appraisal campaigns for deepwater environments are a continuous challenge in today's operations. Data acquisition in such environments requires reservoir information of the highest quality before expensive development plans can be put in place. New technology, real time monitoring and integrated reservoir data are essential to understand such reservoirs. Another challenge presented by thinly bedded reservoirs is the presence of vertical heterogeneity and varying layer flow properties.Wireline formation testers have been commonly used to acquire formation pressures pressure and reservoir fluid samples for a number of decades. Many hardware technologies and interpretation methods have been developed to acquire better quality reservoir information. Dual packer wireline formation testers offer an alternative an additional way to selectively straddle a section of a reservoir and provide the capability to conduct controlled local production and interference as well as to enable the capture of reservoir fluids. Formation permeability, anisotropy, skin factor, vertical connectivity and zonal productivity index are additional reservoir information that can be obtained from a mini-Drill Stem Test (mini-DST) and a Vertical Interference Test (VIT).Pressure transient analysis of a mini-DST data however in such reservoirs is challenging due to the associated uncertainties such as layer flow compartments and flowing fluid viscosity. This paper discusses the use of integrated reservoir information obtained from Downhole Fluid Analyzers (DFA), borehole images, and numerical simulation models to minimize these uncertainties. A systematic pressure transient analysis method for mini-DSTs is also introduced. * Currently with Santos Ltd.Reservoir parameters obtained from mini-DSTs in thinly laminated deepwater reservoirs are then compared with other available static and dynamic reservoir information such as petrophysical data, core analysis, well tests, production logs, and single probe wireline formation tests in order to obtain accurate interpretation results of highest consistency.Field examples will be discussed which show that smaller scale pressure transient tests often have an advantage over full scale well tests testing in terms of providing detailed layer flow behavior, vertical connectivity and flow potential in thinly bedded environments. It will also be noted that the radius of investigation of a mini-DST is limited, typically within tens of feet. This paper demonstrates using field examples that reservoir boundaries can be detected when sufficient radius of investigation is achieved. In addition, the understanding of limitations and advantages will allow the proper selection of test types in order to meet specific objectives and maximize the full potential use of acquired data for field development plans in thinly laminated deepwater environments.

show abstract

Mini-DST Applications for Shell Deepwater Malaysia

Daungkaew

¹

,

Harfoushian

²

,

Cheong

³

et al. 2007

Asia Pacific Oil and Gas Conference and Exhibition

View full text Add to dashboard Cite

fax 01-972-952-9435. AbstractExploration and appraisal campaigns for deepwater environments are a continuous challenge in today's operations. Data acquisition in such environments requires reservoir information of the highest quality before expensive development plans can be put in place. New technology, real time monitoring and integrated reservoir data are essential to understand such reservoirs. Another challenge presented by thinly bedded reservoirs is the presence of vertical heterogeneity and varying layer flow properties.Wireline formation testers have been commonly used to acquire formation pressures pressure and reservoir fluid samples for a number of decades. Many hardware technologies and interpretation methods have been developed to acquire better quality reservoir information. Dual packer wireline formation testers offer an alternative an additional way to selectively straddle a section of a reservoir and provide the capability to conduct controlled local production and interference as well as to enable the capture of reservoir fluids. Formation permeability, anisotropy, skin factor, vertical connectivity and zonal productivity index are additional reservoir information that can be obtained from a mini-Drill Stem Test (mini-DST) and a Vertical Interference Test (VIT).Pressure transient analysis of a mini-DST data however in such reservoirs is challenging due to the associated uncertainties such as layer flow compartments and flowing fluid viscosity. This paper discusses the use of integrated reservoir information obtained from Downhole Fluid Analyzers (DFA), borehole images, and numerical simulation models to minimize these uncertainties. A systematic pressure transient analysis method for mini-DSTs is also introduced. * Currently with Santos Ltd.Reservoir parameters obtained from mini-DSTs in thinly laminated deepwater reservoirs are then compared with other available static and dynamic reservoir information such as petrophysical data, core analysis, well tests, production logs, and single probe wireline formation tests in order to obtain accurate interpretation results of highest consistency.Field examples will be discussed which show that smaller scale pressure transient tests often have an advantage over full scale well tests testing in terms of providing detailed layer flow behavior, vertical connectivity and flow potential in thinly bedded environments. It will also be noted that the radius of investigation of a mini-DST is limited, typically within tens of feet. This paper demonstrates using field examples that reservoir boundaries can be detected when sufficient radius of investigation is achieved. In addition, the understanding of limitations and advantages will allow the proper selection of test types in order to meet specific objectives and maximize the full potential use of acquired data for field development plans in thinly laminated deepwater environments.

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Forecasting the Productivity of Thinly Laminated Sands with a Single Well Predictive Model

Daungkaew

¹

,

Claverie

²

,

Cheong

³

et al. 2008

SPE Asia Pacific Oil and Gas Conference and Exhibition

14

0

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As the cost of exploration wells continue to escalate, we need more than ever to evaluate each well quickly and efficiently to improve the appraisal process and avoid unnecessary expenditure. At the same time, an accurate reservoir characterization is the key to successful reservoir development. This is especially true in thinly laminated reservoirs which exhibit vertical heterogeneity and a wide range of flow properties. Therefore, it is critical to combine high resolution formation evaluation logs and formation tests to predict the well performance prior to the production test. We present an integrated and structured approach for calculating the productivity of a laminated clastic reservoir and we illustrate the method with a field example from Malaysia. A single well predictive model incorporates logs, rock and PVT data, and formation tests to build a flow simulation model at the resolution of the petrophysical analysis. By calibrating the high resolution flow model with dynamic test data from a formation tester Interval Pressure Transient Test (IPTT), the model can be used to predict the well performance. We investigate several key characteristics of thinly laminated reservoirs that affect the well productivity, such as vertical communication between layers. In particular, we examine the effects of clay, silt and sand laminations geometry on the reservoirs productivity. For that purpose, we comment on the information from borehole electrical images, NMR logs, single probe and dual packer wireline formation testers, and production well tests. The workflow is fast to implement as it can be accomplished quickly and efficiently after the well is drilled, in time for planning the well completion and production tests. The high resolution simulation model permits to conduct further engineering studies, whenever required, such as designing the injection and production test for multi-layer reservoirs and water or gas coning studies. Introduction These Deepwater turbidite shallow marine to lower coastal plain reservoirs are composed of interbedded porous/permeable sands with varying percentages of interbedded silt and clay beds. These reservoir sands vary in thickness from millimeter to meters. The reservoirs sands may be highly permeable, but the silt and clay laminations affect the reservoir vertical permeability in each layer. As a result, there are significant vertical heterogeneities in theseis types of reservoirs. It is widely known that the conventional logs may not be able to detect these thinly bedded reservoirs due to their limited insufficient vertical resolution. Therefore, new technology logging services, such as tri-axial resistivity, high resolution oil-base borehole images and nuclear magnetic resonance (NMR) logs have been increasingly used over recent years to help determine an accurate reservoir pay thickness (Ref. 1). In addition to these new logging techniques, interpretation methods such as Log Enhanced Resolution using Borehole Image (SHARP analysis) have been developed to improve the reservoir characterization of these thinly bedded reservoirs (Ref. 2 and 3). After reservoir characterization, other frequently asked questions for thinly bedded reservoir are:What is the productivity of a well drilled in this type of reservoir?What is the connectivity between wells drilled in this type of reservoir? Answers of these questions allow us to evaluate reservoir recoverable reserves. Traditionally, a full scale well test and an interference test are conducted to determine well productivity and well-to-well connectivity, respectively.

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Methods for Real-Time and High-Resolution Formation Evaluation and Formation Testing of Thinly Bedded Reservoirs in Exploration Wells

Cited by 3 publications

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Mini-DST Applications for Shell Deepwater Malaysia

Mini-DST Applications for Shell Deepwater Malaysia

Mini-DST Applications for Shell Deepwater Malaysia

Forecasting the Productivity of Thinly Laminated Sands with a Single Well Predictive Model

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