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Results
Inversion of Wireline Formation Tester Data to Estimate In-Situ Relative Permeability and Capillary Pressure
Cig, Koksal (Schlumberger) | Ayan, Cosan (Schlumberger) | Kristensen, Morten (Schlumberger) | Liang, Lin (Schlumberger) | El Battawy, Ahmed (Schlumberger) | Elshahawi, Hani (Shell) | Ramaswami, Shyam (Shell) | Mackay, Eric (Heriot-Watt University)
Abstract Relative permeability and capillary pressure curves are crucial inputs for a reservoir description. However, measuring these quantities on core samples in the laboratory is an extensive and time-consuming process. Wireline Formation Tester (WFT) logging is routinely applied in field operations for reservoir evaluation purposes. Often a historical record of WFT data exists for a field which can be re-interpreted, and since this interpretation takes days, rather than months to years in the case of core analysis, we propose in this paper to revisit the acquired WFT data with the purpose of estimating multiphase flow properties. WFT logging is generally conducted in an open hole environment. By the time of logging, the near-wellbore region has been exposed to mud filtrate invasion. In the case of immiscible mud filtrate and formation fluid the invasion resembles a small scale water-flood process. During WFT sampling the mud filtrate is first cleaned and formation fluid subsequently sampled in a multiphase flow environment while measuring bottom-hole pressures and water-cuts. As shown in previous papers (Cig et al., 2014, 2015), the measured WFT data can be utilized in an inversion workflow to estimate relative permeabilities by combining a forward model of the cleanup process with an optimization engine. The proposed methodology starts with an open hole log interpretation which provides reservoir properties including a saturation distribution. The filtrate invasion is represented as accurate as possible from the open hole logs and drilling reports. WFT tool geometry and its internal tool storage and fluid segregation effects are incorporated into the modeling. A numerical forward model is then simulated within an optimization workflow where relative permeabilities, capillary pressures, damage skin, and depth of mud filtrate invasion are estimated by minimizing a misfit function between measured and modeled bottom-hole pressures and water-cuts. Industry accepted parameterization techniques are used for the relative permeability and capillary pressure curves. Initial parameter estimates are provided from the interpretations of the open hole logs, such as resistivity, dielectric, nuclear magnetic resonance, as well as from pressure transient analysis. Previously we have studied WFT data from a 3D radial probe (3DRP) and a dual packer (DP) (Cig et al., 2014, 2015). The proposed methodology was also validated with synthetic datasets in the same papers. In this paper we extend the methodology to a single probe (SP) inlet and to joint inversion of both capillary pressure and relative permeability curves. We demonstrate the methodology using field data from a Central Asian clastic reservoir. Interpretation of multiphase flow properties from WFT data represents a valuable complement to core measurements and will help to condition reservoir models for more reliable forecasting.
- Asia (0.94)
- Europe (0.93)
- North America > United States > Texas (0.68)
Flow Modeling and Comparative Analysis for a New Generation of Wireline Formation Tester Modules
Kristensen, Morten (Schlumberger) | Ayan, Cosan (Schlumberger) | Chang, Yong (Schlumberger) | Lee, Ryan (Schlumberger) | Gisolf, Adriaan (Schlumberger) | Leonard, Jonathan (Schlumberger) | Corre, Piere-Yves (Schlumberger) | Dumont, Hadrien (Schlumberger)
Abstract Wireline formation testing (WFT) is an integral part of reservoir evaluation strategy in both exploration and production settings worldwide. Application examples include fluid gradient determination, downhole sampling, fluid scanning in transition zones, as well as interval pressure transient tests (IPTTs). Until recently, however, formation testing was still challenging and prone to failure when testing in low-mobility, unconsolidated, or heavy-oil-bearing formations, especially with single-probe type tools. A new-generation WFT module with a 3D radial probe expands the operating envelope. By using multiple fluid drains spaced circumferentially around the tool, the new module can sample in tighter formations and sustain higher pressure differentials while providing mechanical support to the borehole wall. We performed a detailed flow modeling-based analysis of the contamination cleanup behavior during fluid sampling with the new module. Using both miscible (sampling oil in oil-based mud) and immiscible (sampling oil in water-based mud) contamination models we studied the cleanup behavior over a wide range of formation properties and operating conditions. Comparison of the cleanup performance of the new module with the performance of conventional single-probe tools demonstrates that the new module is 10 to 20 times faster than the single-probe tools when sampling in tight formations. Finally, we also compared the new module against the sampling performance of dual packers and a focused probe. This work is directly relevant to the planning and fundamental understanding of wireline fluid sampling. The key contributions are miscible and immiscible contamination cleanup models that include the effect of tool storage, a comprehensive analysis of contamination cleanup behavior for the new-generation WFT module with comparisons against conventional single-probe, focused probe, and dual-packer tools, and a characterization of fluid sampling conditions versus the preferred type of sampling tool.
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
- (2 more...)
Flow Modeling and Comparative Analysis for a New Generation of Wireline Formation Tester Modules
Kristensen, Morten (Schlumberger) | Ayan, Cosan (Schlumberger) | Chang, Yong (Schlumberger) | Lee, Ryan (Schlumberger) | Gisolf, Adriaan (Schlumberger) | Leonard, Jonathan (Schlumberger) | Corre, Piere Yves (Schlumberger) | Dumont, Hadrien (Schlumberger)
Abstract Wireline formation testing (WFT) is an integral part of reservoir evaluation strategy in both exploration and production settings worldwide. Application examples include fluid gradient determination, downhole sampling, fluid scanning in transition zones, as well as interval pressure transient tests (IPTTs). Until recently, however, formation testing was still challenging and prone to failure when testing in low-mobility, unconsolidated, or heavy-oil-bearing formations, especially with single-probe type tools. A new-generation WFT module with a 3D radial probe expands the operating envelope. By using multiple fluid drains spaced circumferentially around the tool, the new module can sample in tighter formations and sustain higher pressure differentials while providing mechanical support to the borehole wall. We performed a detailed flow modeling-based analysis of the contamination cleanup behavior during fluid sampling with the new module. Using both miscible (sampling oil in oil-based mud) and immiscible (sampling oil in water-based mud) contamination models we studied the cleanup behavior over a wide range of formation properties and operating conditions. Comparison of the cleanup performance of the new module with the performance of conventional single-probe tools demonstrates that the new module is 10 to 20 times faster than the single-probe tools when sampling in tight formations. Finally, we also compared the new module against the sampling performance of dual packers and a focused probe. This work is directly relevant to the planning and fundamental understanding of wireline fluid sampling. The key contributions are miscible and immiscible contamination cleanup models that include the effect of tool storage, a comprehensive analysis of contamination cleanup behavior for the new-generation WFT module with comparisons against conventional single-probe, focused probe, and dual-packer tools, and a characterization of fluid sampling conditions versus the preferred type of sampling tool. Introduction A logical start for any wireline formation testing (WFT) operation is a tool string design that considers the formation evaluation objectives and expected formation and fluid properties. With the current availability of an arsenal of probes having different shapes, focused probes of circular or elongated design, and dual packers, this planning stage has now become a more complex process. The recently introduced 3D radial probe (Al Otaibi et al. 2012; Flores de Dios et al. 2012) adds another choice for the engineers in planning WFT surveys.
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Formation test analysis (e.g., wireline, LWD) (1.00)
Abstract Knowing the H2S concentration early in the exploration and appraisal phase of a potential hydrocarbon discovery is critical for proper planning of the development phase. Production from a newly discovered accumulation often requires tie-in to an existing pipeline or facility, which usually has an upper limit on how much H2S can be handled, if any. The presence of H2S also affects the design of the completion and the production systems. Not discovering H2S until the production phase can halt production while the surface facilities are upgraded to handle the sour gas, which can be very expensive. Several publications have shown that using standard wireline formation testing (WFT) to obtain fluid samples without adequate planning and preparation may result in H2S being scavenged during sampling or during transfer. In addition, standard gas chromatography (GC) analysis may measure small H2S concentrations inaccurately. Alternative methods for sampling and conserving small H2S concentrations have been proposed, but they are supported only by laboratory tests with no actual field data published. In this paper, we present case studies of applying low H2S concentration sampling in the field. The wireline formation sampling was designed to capture samples with very small amounts of H2S under field conditions. This includes selection of the materials used in the sampling tool, tool string setup, choice of coating material for the sampling bottles, transfer of samples and analysis. The flow path inside the sampling tool was reduced to minimize the potential loss of H2S. In addition to wireline formation testing, the wells were also tested using a traditional drillstem test (DST). The results of the well test and the wireline sampling agreed well in both cases.
- North America > United States (0.28)
- Europe > United Kingdom > North Sea (0.28)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > Greater Stella Area > Block 30/6a > Stella Field > Stella Ekofisk Formation > Stella Well (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > Greater Stella Area > Block 30/6a > Stella Field > Stella Andrew Formation > Stella Well (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > Greater Stella Area > Block 30/6-2 > Stella Field > Stella Ekofisk Formation > Stella Well (0.99)
- (5 more...)
- Reservoir Description and Dynamics > Formation Evaluation & Management (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Health, Safety, Environment & Sustainability > Health > Noise, chemicals, and other workplace hazards (1.00)
New Wireline Formation Tester Development Makes Sampling and Pressure Testing Possible in Extra-Heavy Oils in Mexico
Flores de Dios, Tania (PEMEX) | Aguilar, Maria Guadalupe (PEMEX) | Herrera, Rafael Perez (PEMEX) | Garcia, German (PEMEX) | Peyret, Emilie (Schlumberger) | Ramirez, Edher (Schlumberger) | Arias, Abraham (Schlumberger) | Corre, Pierre-Yves (Schlumberger) | Slapal, Miroslav (Schlumberger) | Ayan, Cosan (Schlumberger)
Abstract Accurate fluid description in the Tertiary sediments of Mexico is important for PEMEX operating assets because large variations in viscosity over very short intervals have a major impact on well productivity. Well placement and selection of the completion strategy in this kind of reservoirs strongly depend on the characterization of the fluid distribution. This is because the efficiency of steam injection and the artificial lift system can be severely impaired if a preferential path, following high mobility section (k/μ) exists over the producing intervals. Such is the case for the Samaria-Neogeno project, which has fluids with viscosity values up to 40,000 centipoise (cP) at standard conditions. Wireline openhole formation testing and sampling in this environment is not short of challenges and hence is rarely done in the field. The poorly consolidated formations and the high viscosity of the fluids mean that the pressure differential generated during sampling operations almost invariably causes failure of the wellbore wall, sanding out the tool or breaking the seal needed. Other experiences in the world with straddle packers in similar formations have been mostly unsuccessful because the formation collapses in the unsupported interval between the packers once the pressure differential is applied. This paper summarizes the recent successful application of the newest wireline formation tester (WFT) module for testing and sampling extra-heavy oils in the Tertiary sandstone formations of South Mexico. This is the world's first application of such technology in unconsolidated sandstones. The new WFT module provides mechanical support to the formation while allowing the application of the needed pressure differentials to mobilize formation fluid into the tool's flowline and sample containers. The case presented shows how ~8° API fluid samples with viscosities in the order of few thousands centipoises at downhole conditions were acquired using this new device. Other applications reviewed are pressure profiling and pressure transient tests for permeability evaluation.
- North America > Mexico (1.00)
- North America > United States > Texas (0.29)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.74)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.72)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > Mexico Government (0.68)
- North America > Mexico > Tabasco > Sureste Basin > Reforma Basin > Samaria Field (0.97)
- North America > Mexico > Tabasco > Sureste Basin > Reforma Basin > A. J. Bermudez Complex Field > Iride Field (0.94)
Comparing Wireline Formation Tester Derived Productivity Index to Drill Stem Test
Khong, Chee Kin (Schlumberger) | Li, Chen (Schlumberger) | Ayan, Cosan (Schlumberger) | Xu, Liqiang (CNOOC Zhanjiang Ltd) | Jun, Cai (CNOOC Zhanjiang Ltd) | Guo, Shusheng (CNOOC Zhanjiang Ltd) | Wang, Wu Mu (CNOOC Zhanjiang Ltd) | Zhongtian, Hao (CNOOC Zhanjiang Ltd) | Fuxi, Pan (CNOOC Zhanjiang Ltd) | Zhongjian, Tan (CNOOC Zhanjiang Ltd) | Jun, Yang Hong (CNOOC Zhanjiang Ltd)
Abstract Drill stem test (DST) derived average effective permeability and productivity is our industry's accepted standard but DST expenses are not always justified especially in development wells. Although zonal contribution could be measured by production logging survey but this requires an additional well intervention operation and most likely interruption of production as well. Zonal productivity modeled correctly in a well is of immense value for reservoir management. In exploration well, accurate productivity index prior to DST is invaluable for operational planning, while in development well accurate productivity index is crucial for completion design. If dynamic data is not available, zonal productivity had been estimated based on permeability derived from petrophysical log data. Single probe open-hole wireline formation tester (OH-WFT) pretest mobility is often used to calibrate log data estimated permeability. However, OH-WFT pretest almost always measure the invaded or drilling induced damaged zone and is at a scale much smaller than DST derived average permeability. Interval Pressure Transient Test using wireline formation tester estimate permeability further away from invaded or drilling induced damaged zone provides a more accurate permeability measurement. Multi-probe or Single-probe WFT is an attractive option when borehole condition does not allow wireline formation tester with straddle packer (WFT-PA) operation. For Single-probe WFT data, permeability anisotropy has to be assumed while permeability anisotropy can be calculated from Multi-probe or Packer-probe pressure data. WFT estimated permeability from pressure transient analysis allows zonal productivity to be calculated, utilizing also pressure, temperature, fluid data, zonal thickness, completed interval and formation dip data. Log data modeled zonal productivity from static data had resulted in off-forecast compared to actual well performance. In this paper, multi-probe and packer-probe wireline formation tester permeability test is used to derive zonal productivity. This productivity estimate is compared to actual DST productivity index.
- Asia (0.68)
- North America > United States > Texas (0.47)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Formation test analysis (e.g., wireline, LWD) (1.00)
Abstract Following the introduction of pressure-rate (p-r) deconvolution techniques in 1960s, they have been investigated continually during the last two decades. Now most p-r deconvolution techniques are stable and have been used increasingly for analysis of pressure transient tests. A successful p-r deconvolution can transform a multirate pressure transient response to an equivalent constant-rate drawdown response for the entire test duration. It can help identify/confirm interpreted reservoir models and eliminates multirate superposition effects. However, the flow rate is usually not directly and continuously measured in conventional pressure-transient well tests, although it is measured reasonably accurately during interval pressure transient tests (IPTT) conducted by wireline formation testers (WFTs). Nevertheless, large uncertainties or errors associated with inaccurate rate data usually hinder the successful use of p-r deconvolution methods. When pressure data are available at both the source/sink and observation location(s), for instance interference tests, then pressure-pressure (p-p) deconvolution techniques, through which the flow rate is eliminated from the formulation, can be utilized for analysis of multipoint pressure transient data. Although p-p convolution/deconvolution was first introduced in 1991 by Goode et al. for interpretation of multi-point wireline formation tester pressure transient data, there have been only a few papers published in the literature about p-p deconvolution. In this paper, we investigate in detail the use of p-p deconvolution for interpretation of conventional multiwell interference and interval pressure transient tests. It is shown that the recent deconvolution algorithms developed for p-r deconvolution can also be used for performing p-p deconvolution by simply replacing the rate data in p-r deconvolution algorithms by the pressure change data recorded at the source/sink location or at one of the observation locations. In this paper, we use the Pimonov et al. (2009) p-r deconvolution algorithm that utilized a more general weighted least-squares objective function compared to previous techniques. We demonstrate the practical utility of p-p deconvolution by considering both synthetic and real (field) transient test data sets from IPTTs and multiwell interference tests. Introduction Focus in deconvolution has recently increased, following the introduction of more stable p-r deconvolution algorithms (von Schroeter et al. 2004; Levitan 2005; Levitan et al. 2006; Ilk et al. 2006; Onur et al. 2008; Pimonov et al. 2009). Ratepressure (r-p) deconvolution (Kuchuk et al. 2005) for decline curve analysis and multiwell p-r deconvolution (Levitan 2007) have also been used. Successful deconvolution of well test data or interval pressure transient test (IPTT) data enables the analyst to identify reservoir behavior without the effects of multirate production, as if the well had been flowing with a constant flow-rate from the start of the test period, but may still be affected by the wellbore storage if the flow rate is not measured at the sandface. This deconvolved constant-rate drawdown data increase the radius of investigation to the duration of the entire multiple flow and buildup tests; consequently it provides data for better reservoir characterization and reserve estimation.
- North America > United States > Texas (0.67)
- North America > United States > California (0.46)
Abstract Many sedimentary features of gas fields are multilayered, deltaic, thinly laminated shaly sandstones consisting of channel and bar sands with limited lateral and vertical extension. Relying only on conventional openhole log data and performing correlations among nearby wells proved to be inconclusive in identifying gas reservoirs owing to their thin beds, high shale content, and variable formation water resistivity. Missing gas-bearing formations translates into lost productivity, while perforating water zones can have detrimental effects on well performance. Moreover, the limited lateral extent of these relatively tight gas sands leads to extremely depleted reservoirs alternating with layers with virgin zone pressures. As a consequence, the depleted layers face a significant overbalance while drilling with an oil-base mud system. Given these complexities, fluid identification and pressure measurements have a significant impact in resolving key uncertainties of such reservoirs. The main challenges faced during formation testing in the reservoirs studied have been a) laminated, low mobility and thin formations with varying water salinity, b) high depletion, resulting in extreme overbalance for some layers in new wells, c) possible formation damage while drilling, d) cable creep while station logging. Several different approaches have been recently launched to increase the success ratio of wireline formation testers (WFT's) in getting reliable pressures and fluid analysis, including real-time monitoring of each survey by reservoir engineers. This paper describes the development path and results from the new techniques:extra-large diameter probe, elliptical probe, the openhole driller, cable creep correction and extra-extra high displacement pump unit. We will present each project and its impact on the improvement of WFT tester success ratio in such challenging environments. Introduction The predominant sedimentary features in the reservoirs we focus are very thinly laminated shaly sands composed of 70–80% quartz plus feldspar and clays (kaolinite and illite), in which gas sands are not in pressure communication. Figure 1 shows an image log of a 4-meter section where very fine layering is evident. Vertical heterogeneity on various scales lead to multiple gas/water contacts with extremely depleted and virgin zones in the same well, thus resulting in very high over-balance; commonly in excess of 6000 psi and occasionally up to 10000 psi differential pressure. The shale quantity and thin-beds very often results in conventional logs giving wrong fluid determination, therefore fluid analysis using wireline formation testers is a very important step during the open hole evaluation stage. As noted, these conditions are quite challenging for formation testing. Some of these challenges, particularly near wellbore formation alteration have been studied using a multi-probe wireline formation tester (Ayan et al., 2007). In this study, the authors used dipole radial profiling and Interval Pressure Transient Tests (IPTT) and showed that possible formation damage does not necessarily increase with increasing overbalance. Some operational aspects of wireline formation testing have been discussed for such environments (Ferment et al. 2004), highlighting issues with high differentials, probe plugging, fine laminations and depth control. Over the past 20 years, in the formations we focus in this study, the operational success ratio of downhole formation pressure testing (valid test vs. total tests) has remained at an average of 30% despite technological innovations in both wireline and drilling. In Table 1, we summarize the main reasons causing low pretest success ratio. To increase the success ratio for pressure testing and downhole fluid identification, a multitude of solutions were proposed. In this study, we describe each of them and the results achieved following their introduction.
- Asia (0.94)
- North America > United States > Texas (0.28)
- Geology > Mineral > Silicate (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.89)
- Geology > Sedimentary Geology > Depositional Environment > Transitional Environment > Deltaic Environment (0.60)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.46)
Abstract Wireline Formation Tester (WFT) pretest success ratio (good versus tight pressure points) has been traditionally low in East Kalimantan-Indonesia over decades despite technological advances. One possible reason has been postulated as alteration of near-wellbore formation properties during drilling operations. The relatively tight gas sands are drilled with significant overbalance due to a mix of depleted and virgin zone layers using oil based mud systems. To further investigate possible near formation alteration, an extensive evaluation program was undertaken, using new generation sonic logs, WFT-multi-probe interval pressure transient testing (IPTT) and coring. A Sonic Scanner* survey was conducted in Tunu field to investigate possible nearby formation alteration, followed by MDT*-multi-probe IPTT. The Sonic Scanner dipole radial profiling showed some radial property change at several zones. The altered zone radial extent was quantified. The MDT-IPTT tests quantified the, virgin zone effective gas permeability and permeability anisotropy as well as gave a fair idea of the open hole skin factor. Combination of the results gave altered zone radius, altered zone permeability, virgin zone permeability and anisotropy on a comparative basis between different zones. Moreover, the results from both dipole radial profiling and MDT-IPTT indicated that formation alteration not necessarily increases with overbalance. The results quantified nearby formation alteration, showed this as a possibility and can further help in selecting the best perforation strategy. Introduction In the tight and laminated sands of East Kalimantan, Indonesia, obtaining pressures with Wireline Formation Testers has always been difficult. This naturally affects the success of sampling and downhole fluid analysis performed subsequently after the probe pressure measurements. Until recently, higher temperatures, six inch hole size and Oil Based Mud (OBM) limited the use of dual packer tools in this environment, which could be a better solution depending on the number of test points desired. Though the fine laminations of the tight gas sands is a major reason for observing low success statistics of communicating with the formation, other possibilities have been postulated. One of the possibilities is the alteration of near formation properties due to drilling fluid invasion. Some mechanisms that can cause damage due to OBM invasion are:Emulsion blocking - emulsions may form between the filtrate, formation fluids and connate water. Relative permeability effects - most pronounced in tight, water-wet gas sands where oil based mud filtrate is the third phase introduced into a two-phase system, thereby reducing the relative permeability to gas. This usually results in longer cleanup times, especially in tight formations. iii. Fines migration - another reason for near wellbore formation alteration could be wettability change due to OBM invasion. Such drilling fluids usually have surfactants as additives, and an excess amount may change the wettability of water wet particles in the formation to oil wet. These particles, which are originally immobile may then be mobilized and can cause near wellbore formation damage. iv. Plugging by particulates, particularly fluid loss control additives -certain additives may cause damage by plugging pore throats in an irreversible manner.
- Asia > Indonesia > Kalimantan (0.45)
- Asia > Indonesia > East Kalimantan > Makassar Strait (0.24)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
Summary Modern wireline formation testers (WFTs) are able to collect a massive amount of data at multiple depths, thus helping to quantify changes in rock and fluid properties along the wellbore, to define hydraulic flow units, and to understand the reservoir architecture. They are being used routinely in a wide range of applications spanning pressure and mobility profiling vs. depth, fluid sampling, downhole fluid analysis (DFA), interval pressure-transient testing (IPTT), and microfracturing. Because of the complex tool strings and the elaborate operational aspects involved in wireline formation testing, success requires detailed upfront planning and procedural design as well as real-time operational and interpretational support. It is becoming increasingly critical for operating and service company experts to remotely monitor and interpret WFT surveys in real time through Web-based systems. The importance of meeting all rock and fluid data-acquisition objectives cannot be overstated, given the high cost of offshore operations and the implications of obtaining false or misleading information. The main objective of real-time monitoring remains to assure that the planned data are acquired according to pre-established procedures and contingency plans. However, even in developed reservoirs, unexpected circumstances arise, requiring immediate response and modifications to the preplanned job procedures. Unexpectedly low or high mobilities, probe plugging, unanticipated fluid types, the presence of multiple phases, and excessive fluid contamination are but a few examples of such circumstances that would require real-time decision making and procedural modifications. Real-time decisions may include acquiring more pressure data points, extending sampling depths to several zones, extending or shortening sampling times, and repeating microhydraulic fracture reopening/closure cycles, as well as real-time permeability, composition, or anisotropy interpretation to determine optimum transient durations. This paper describes several examples of formation tester surveys that have been remotely monitored in real time to ensure that all WFT evaluation objectives are met. The power of real-time monitoring and interpretation will be illustrated through these case studies. Introduction WFT has become a standard part of the evaluation program of most newly drilled wells, but the objectives vary from offshore deepwater exploration and appraisal wells to old cased-hole and development wells later in the life of a field. Given the wide range of applications and combinations, each WFT evaluation program is unique. Some may include only a pressure-gradient survey for reservoir depletion and communication information, whereas others may seek information on the precise nature of the hydrocarbon fluids and water in terms of chemical and physical properties, phase behavior, and commingling tendencies. Cased-hole surveys might look for bypassed hydrocarbon zones or have objectives that could not be achieved during the openhole phase. Regardless of the type of survey performed, understanding the exploration and appraisal or field-development objectives and translating these into acquisition objectives is essential for success. Figs. 1 and 2 schematically illustrate the real-time monitoring concept. Real-time data are viewable by authorized personnel anywhere around the world, thus allowing virtual collaboration between field staff and off-site service- and operating-company experts throughout the operation. This paper includes several examples of WFT surveys that were monitored and supervised in real time. The cases presented span the entire spectrum of WFT applications including pressures, gradients, sampling, downhole fluid analysis (DFA), IPTT, and microfracturing. The power of real time monitoring and interpretation is clearly illustrated by these examples.
- North America > United States (1.00)
- Europe (1.00)
- Asia > Middle East > Israel > Mediterranean Sea (0.48)
- Europe > United Kingdom > North Sea > Northern North Sea > South Viking Graben > Block 9/23a > Tullich Field > Balder Formation (0.99)
- Europe > Norway > North Sea (0.91)
- Europe > Netherlands > North Sea (0.91)
- Europe > Denmark > North Sea (0.91)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Formation test analysis (e.g., wireline, LWD) (1.00)
- (2 more...)