Gulf of Thailand

Pore Pressure Estimation by Using Machine Learning Model

Booncharoen, Pichita (Chevron Thailand Exploration and Production) | Rinsiri, Thananya (Chevron Thailand Exploration and Production) | Paiboon, Pakawat (Chevron Thailand Exploration and Production) | Karnbanjob, Supaporn (Chevron Thailand Exploration and Production) | Ackagosol, Sonchawan (Chevron Thailand Exploration and Production) | Chaiwan, Prateep (Chevron Thailand Exploration and Production) | Sapsomboon, Ouraiwan (Chevron Thailand Exploration and Production)

OnePetroMarch, 2021

Abstract In the past few years, over hundreds of wells were drilled in Gulf of Thailand, had faced with the depletion and lost circulation issues resulted from a lack of pressure data. A prior research of reservoir depletion pressure (Fangming, 2009) in oil field, China was obtained from multivariate statistic and regression by using density and neutron porosity log curves in logging-while-drilling data. However, the relative errors are 7.5% from the actual formation pressure. Thus, there are several latent variables in the model like drilling parameters (Rehm, 1971) which part of formation pressure. From 2018 initiative model in Satun-Funan, the classification model was obtained by using mud gas, porosity, water saturation, net sand thickness, net-hydrocarbon-pore thickness and neutron-density separation. However, the limitation is drilling parameters could not account by classifier, and accurate only original pressure category. So, this study has expanded scope to include other reservoir properties and drilling parameters then applied with machine learning on offset well dataset by using three regressors such quantile, ridge and XGBoost regressors. The pore pressure estimation model aims to improve efficiency for making decision in execution phase, increasing confidence in perforation strategy. The model parameters, pay thickness, porosity, water saturation, original pressure from local pressure profile and total gas show are accounted into this model. As of regressor assumption, some facts are conducted to logarithm and perform 2nd polynomial feature for model flexibility. There are three steps for building model such as data manipulation, analysis and deployment. Two purposes of pressure prediction impact algorithm selection, for operational phase, quantile regressor is implemented to provide conservative prediction while Ridge or XGBoost regressors are alternatives for perforation strategy, provide mid case result of pressure prediction. Overall model performance was measured using root mean square error (RMSE) on train & test dataset which show approximately 1.2 and 1.5 ppg range of accuracy respectively from total 12 drilling projects in Pattani basin. Overall model fitting is within reasonable range of generalization capacity to apply with unknown data point (test set). The future model will continue to improve accuracy and manage imbalanced dataset between original pressure and depleted sands.

OnePetro

doi: 10.2523/IPTC-21490-MS

IPTC

IPTC-21490-MS

International Petroleum Technology Conference

Country:

Asia > Thailand > Gulf of Thailand (0.37)
North America > United States > Louisiana (0.34)
Asia > Vietnam > Gulf of Thailand (0.26)
(5 more...)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

North America > United States > Louisiana > China Field (0.99)
Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
(4 more...)

SPE Disciplines:

Well Drilling > Drilling Operations (1.00)
Well Completion > Completion Installation and Operations > Perforating (1.00)
Reservoir Description and Dynamics > Reservoir Characterization (1.00)
(2 more...)

Technology: Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (1.00)

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Abstract Exploration activity is always associated with many challenges such as uncertain pore pressure, and uncertain formation depths and characteristics. Unconsolidated formation could cause more serious troubles for drilling, formation evaluation, and production such as borehole washout, wellbore collapse, and sanding if proper planning is not in place. In addition, a viscous oil can add another complication for fluid sampling operations. An unsuccessful logging program could have a major impact on the field development plan (FDP) and further field investment decision (FID). In the Gulf of Thailand (GoT), high temperature Pattani basin discovery wells, reservoir fluids are mainly gas and condensate. There are numbers of waxy oil reservoirs1–5 in certain area in the GoT, notably in the cooler peripheral Tertiary basins. However, the subject field is the first one that was identified as having productive heavy oil reservoirs. The viscosity variation ranges between 1 and 100 cp2–6. It was observed that there was a depth related variation with deeper reservoirs having higher viscosities, and therefore, reservoir fluid information is crucial for the FDP and FID resulting from a field extension drilling campaign in early 2018. This paper will discuss step by step (1) reservoir characterization challenges (2) proposed methods to obtain reservoir and fluid information, as well as the interval pressure transient test, (3) the actual field results, (4) recommendations and way forward for similar reservoirs. Different proposed options are also discussed with field examples to obtain high quality PVT samples. Pumping to clean up high viscous oil contaminated tends to attract finer particulates towards the probe and into the flowline, causing plugging issues in other probe types even though a modified sand filter was added. In the end, the 3D Radial probe was proven in making this exploration campaign a success story for acquiring the heaviest oil samples to date in the GoT. The 3D Radial probe equipped with mesh filter plays an important role to restrict ingress of small sand particles, thereby allowing both sustainable pumping speed and flowing pressure. The single packer design also helps to support the formation preventing drawdown collapse. Coupled with larger flow area of the probe itself, the 3D Radial Probe has ability to control flowing pressure to stay above the sand break-away pressure even as more viscous formation oil enters. However, job objectives were achieved, which were formation pressure acquisition, high-quality fluid sampling, and Interval Pressure Transient Testing (IPTT) as well as Vertical Interference Testing (VIT). This paper also discusses the comparison between Downhole Fluid Analysis results and PVT lab analyses. Limitation and challenges for downhole measurements for this heavy oil environment. Advantages and disadvantages for different testing methods for this heavy oil reservoir will also be discussed.

OnePetro

doi: 10.4043/30226-MS

OTC

OTC-30226-MS

Offshore Technology Conference Asia

Country:

Asia > Vietnam > Gulf of Thailand (0.24)
Asia > Thailand > Pattani > Pattani (0.24)
Asia > Thailand > Gulf of Thailand (0.24)
(3 more...)

Geologic Time: Phanerozoic > Cenozoic (0.88)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

South America > Venezuela > Anzoátegui > Eastern Venezuela Basin > Maturin Basin > Cerro Negro Area Field (0.99)
Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
(3 more...)

SPE Disciplines:

Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
Reservoir Description and Dynamics > Reservoir Characterization (1.00)
Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
(3 more...)

Technology: Information Technology (0.47)

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Abstract Exploration activity is always associated with many challenges such as uncertain pore pressure, and uncertain formation depths and characteristics. Unconsolidated formation could cause more serious troubles for drilling, formation evaluation, and production such as borehole washout, wellbore collapse, and sanding if proper planning is not in place. In addition, a viscous oil can add another complication for fluid sampling operations. An unsuccessful logging program could have a major impact on the field development plan (FDP) and further field investment decision (FID). In the Gulf of Thailand (GoT), high temperature Pattani basin discovery wells, reservoir fluids are mainly gas and condensate. There are numbers of waxy oil reservoirs1–5 in certain area in the GoT, notably in the cooler peripheral Tertiary basins. However, the subject field is the first one that was identified as having productive heavy oil reservoirs. The viscosity variation ranges between 1 and 100 cp2–6. It was observed that there was a depth related variation with deeper reservoirs having higher viscosities, and therefore, reservoir fluid information is crucial for the FDP and FID resulting from a field extension drilling campaign in early 2018. This paper will discuss step by step (1) reservoir characterization challenges (2) proposed methods to obtain reservoir and fluid information, as well as the interval pressure transient test, (3) the actual field results, (4) recommendations and way forward for similar reservoirs. Different proposed options are also discussed with field examples to obtain high quality PVT samples. Pumping to clean up high viscous oil contaminated tends to attract finer particulates towards the probe and into the flowline, causing plugging issues in other probe types even though a modified sand filter was added. In the end, the 3D Radial probe was proven in making this exploration campaign a success story for acquiring the heaviest oil samples to date in the GoT. The 3D Radial probe equipped with mesh filter plays an important role to restrict ingress of small sand particles, thereby allowing both sustainable pumping speed and flowing pressure. The single packer design also helps to support the formation preventing drawdown collapse. Coupled with larger flow area of the probe itself, the 3D Radial Probe has ability to control flowing pressure to stay above the sand break-away pressure even as more viscous formation oil enters. However, job objectives were achieved, which were formation pressure acquisition, high-quality fluid sampling, and Interval Pressure Transient Testing (IPTT) as well as Vertical Interference Testing (VIT). This paper also discusses the comparison between Downhole Fluid Analysis results and PVT lab analyses. Limitation and challenges for downhole measurements for this heavy oil environment. Advantages and disadvantages for different testing methods for this heavy oil reservoir will also be discussed.

OnePetro

doi: 10.2118/197437-MS

SPE

SPE-197437-MS

Abu Dhabi International Petroleum Exhibition & Conference

Country:

Asia > Vietnam > Gulf of Thailand (0.24)
Asia > Thailand > Pattani > Pattani (0.24)
Asia > Thailand > Gulf of Thailand (0.24)
(3 more...)

Geologic Time: Phanerozoic > Cenozoic (0.88)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
(2 more...)

SPE Disciplines:

Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
Reservoir Description and Dynamics > Reservoir Characterization (1.00)
Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
(3 more...)

Technology: Information Technology (0.47)

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Observations on Hydrocarbon Migration, Jasmine-Ban Yen Field; Block B5/27, Gulf of Thailand

Clark, S. J. (Mubadala Petroleum) | Davis, R. C. (Mubadala Petroleum)

OnePetroNovember, 2017

Abstract Detailed knowledge of fill-spill history and charge entry points to fields is rarely available, due to lack of suitable data sets and methodologies. This paper describes the application of a reservoir geochemical work flow (multi-variate statistical analysis of geochemical data) to unravel the fill history of a highly complex oil field in the northern Gulf of Thailand, and the implications of these results in assessing charge risk in adjacent and near-field prospects. The Jasmine-Ban Yen field, Pattani Trough, Gulf of Thailand, produces from stacked Middle to Late Miocene clastic reservoirs, draped over a highly faulted structural nose. In an earlier study, 59 oils from across the field underwent standardised fingerprinting, biomarker and bulk isotope analysis. Here, geochemical parameters considered resistant to secondary processes such as biodegradation, underwent hierarchical cluster analysis and classification into fluid families. Distinct families potentially represent fluids that share a common history. The results were synthesised with spatial information, seismic data, reservoir pressures, petroleum systems modelling, and observations drawn from the field's production history, to elucidate the fill-spill history of the field. All oils were expelled from similar lacustrine organofacies at similar maturity, which is broadly consistent with a single source pod charging the field. The closest mature kitchen is thought to be located in the Northern Pattani Trough, some 20 to 25 km to the south. A sub-regional Middle Miocene lacustrine seal, the "hot shale," focusses oil into the Jasmine-Ban Yen field, and forms the seal for 30% of the STOIIP. Fluids also occur in reservoirs above this seal, which could be emplaced either through vertical fill and spill via high offset faults, possibly aided by locally high CO2 increasing buoyancy pressure by formation of a gas cap, or laterally, via spill from adjacent fault blocks. Detailed knowledge of charge history remains elusive; however, the occurrence of consistently different fluid families above and below the hot shale seal, with fluids below represented by consistent families over a lateral distance of 12 km, supports an interpretation of multiple entry points into the field. Aromatic maturity parameters indicate that four Ban Yen samples are of slightly elevated maturity, suggesting that late charge accesses the field above the hot shale. The possibility that the differences between families are related to biodegradation was investigated and discarded. Families probably represent discrete, lateral spill pathways reflecting multiple charge entry points and are differentiated by subtle variations in organofacies related to oxicity and contribution from plant material. Comparable migration above and below the hot shale into B5/27 is a possibility, and exploration prospectivity is risked accordingly. Placing statistically derived fluid families into a spatial, geological and production context enables unravelling of migration vectors in complex fields. Furthermore, inferences may be drawn from such a study that can help guide risk assignment to offset exploration prospectivity.

OnePetro

doi: 10.2118/188576-MS

SPE

SPE-188576-MS

Abu Dhabi International Petroleum Exhibition & Conference

Country:

Asia > Thailand > Gulf of Thailand (0.70)
Asia > Vietnam > Gulf of Thailand (0.55)
Asia > Myanmar > Gulf of Thailand (0.55)
(3 more...)

Geologic Time: Phanerozoic > Cenozoic > Neogene > Miocene (1.00)

Geophysics: Geophysics > Seismic Surveying (0.70)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Dampier Basin > WA-20-L > Legendre Field > Angel Formation (0.99)
Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
(3 more...)

SPE Disciplines:

Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Reservoir Description and Dynamics > Fluid Characterization > Geochemical characterization (1.00)

Technology: Information Technology > Artificial Intelligence > Machine Learning (0.35)

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Shallow Hydrocarbons in the Pattani Trough, Gulf of Thailand

Fujiwara, Masashi (Mitsui Oil Exploration Co. Ltd.) | Takaoka, Shinichi (Mitsui Oil Exploration Co. Ltd.) | Fukuda, Kayo (Mitsui Oil Exploration Co. Ltd.)

OnePetroOctober, 2015

Abstract It has been recognized from the early stages of exploration in the 1980s that gas bearing reservoirs with condensates were located at depths of approximately 4,000 to 5,000 feet in parts of the Pattani Trough, Gulf of Thailand. However, even though the entire pay window is evaluated for each prospect area, no regional study on the shallow hydrocarbons has been made due to the majority of hydrocarbons residing in deeper zones. In the Gulf of Thailand there are two major Cenozoic sedimentary basins, the Pattani Trough and the Malay Basin. In the Pattani Trough, commercial production started at the Erawan gas field in 1981 and subsequently more than 20 oil and gas fields have been discovered and have continued producing hydrocarbons at the current date. The Pattani Trough is a rift type-sedimentary basin and the maximum thickness of sediments is more than 10 km. The geological column is divided into five sedimentary units from Sequence 1 to 5 in ascending order. Two major unconformities are identified: one is called the Middle Cenozoic Unconformity (MCU) and the Middle Miocene Unconformity (MMU). The latter unconformity is located between Sequence 4 and Sequence 5. Oil and gas are mainly trapped in fluvial to deltaic sandstones of Sequence 3 and Sequence 4 located between 5,000 to 9,000 feet. Structure is characterized by many normal faults. Based on the more than 800 wells and 3D seismic data, detailed studies on well correlation, dip-meter, micropaleontology, regional isopachs and sand-shale ratio were made and it was concluded that the these shallow hydrocarbons are closely related to the incised valley-fill sediments located in the lower part of Sequence 5 immediately above the MMU. Hydrocarbons generated in the deeper levels have migrated upward through faults and moved into and are possibly trapped in the incised shallow reservoirs. Previous wells were drilled in the highly faulted areas where most of the oil and gas is trapped and there are no wells drilled in the monocline areas. Although the detailed areal distribution of the incised valleys is not clearly identified, hydrocarbons are expected in monocline areas if conditions are favorable. Since the MMU is widely developed in the South East Asia, this type of exploration concept focusing shallow hydrocarbons can be applied not only for the undrilled area of the Pattani Trough but also for the mature sedimentary basins such as the Malay and Nam Con Son basins.

OnePetro

SPWLA

SPWLA-JFES-2015-U

SPWLA 21st Formation Evaluation Symposium of Japan

Formation Evaluation Symposium, Fujiwara, geological society, Gulf, hydrocarbon, incised valley, Japan, MMU, october 13, Pattani Trough, Reservoir Characterization, sandstone, Satun field, shallow hydrocarbon, structural geology, Thailand, Thickness, unconformity, Upstream Oil & Gas

Country:

Asia > Vietnam > Gulf of Thailand (1.00)
Asia > Thailand > Pattani > Pattani (1.00)
Asia > Thailand > Gulf of Thailand (1.00)
(3 more...)

Geologic Time:

Phanerozoic > Cenozoic > Paleogene (1.00)
Phanerozoic > Cenozoic > Neogene > Miocene > Serravallian (0.35)
Phanerozoic > Cenozoic > Neogene > Miocene > Langhian (0.35)

Geophysics: Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.54)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

North America > Canada > Saskatchewan > Western Canada Sedimentary Basin > Alberta Basin > Viking Formation (0.99)
North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Viking Formation (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin > Contract Area 2 > Satun Field (0.99)
(10 more...)

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)

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Gulf of Thailand Super Cube - Technical Challenges in the Reprocessing of 40 3D Seismic Surveys, 15000sq.km.

OnePetroNovember, 2011

Abstract In early 2008, Chevron Thailand and partners contracted CGGVeritas to reprocess forty of their key 3D seismic surveys in the Pattani Basin, Gulf of Thailand, with a combined area of more than 15,000 sq.km. The 40 surveys had been acquired over a period of 26 years (1979 to 2005) with variable acquisition parameters, geometries and azimuths, which resulted in variable amplitude and frequency content and variable fold or sampling density. The benefit of the reprocessing is enormous, but the technical challenges are just as great. In this paper we present some of the technical challenges and solutions in the data processing work. A) Detecting and correcting navigation errors in vintage data. Old surveys tend to have navigation errors. Some errors are not obvious until merging with adjacent surveys. We show how we detect the errors and correct them. B) Data regularization. The data of the 40 surveys were loaded into common grid and offset slots for imaging. A challenge is to bridge any acquisition gaps caused by existing platforms at the time of acquisition. Using advanced interpolation technology, we filled in gaps as wide as 350m. C) Offset-dependent matching of frequency bandwidth, amplitude, time and phase between surveys. We present a workflow that was tested and implemented successfully. D) Fault imaging. We show how fault imaging was improved by incorporating anisotropy in migration. Introduction The Gulf of Thailand Super Cube project in the Pattani Basin was initiated and financed by Chevron Thailand, and carried out by CGGVeritas over a period of 3 years. The project area is shown in Figure 1. The 40 3D seismic surveys cover approximately 15,000 sq. km. Prior to the current project, the data had been processed individually or in small groups for use in interpreting individual field areas. The primary objective of the reprocessing was to produce superior seismic imaging by making use of more advanced processing technology, and by making use of neighbouring surveys as migration aperture input. Specifically, the reprocessing aimed to accurately define the principal faults, and to broaden bandwith for high resolution definition of the reservoirs and near water bottom reflectors for the assessment of drilling hazards. The reprocessing also brought about other benefits, which include: regional consistency with DHI or AVO assessment; continuous regional interpretation and data management; fewer seismic volumes to manage; reducing the number of (redundant) faults and horizons in the database; and conveniently working in multiple field areas without the need to switch seismic workstation projects during an interpretation session. The 40 surveys were acquired over a time span of 26 years (1979 to 2005) with variable acquisition parameters, geometries and azimuths, which resulted in variable amplitude and frequency content and variable fold or sampling density. To merge them seamlessly requires great effort in spectral conditioning, time/phase matching, and AVO characteristics preservation. In addition, for some vintage surveys, essential information such as source signature, accurate navigation and well preserved trace data could be missing or incomplete. The essential information had to be cross-examined and reconstructed to facilitate the reprocessing.

OnePetro

doi: 10.2523/IPTC-15039-MS

IPTC

IPTC-15039-MS

International Petroleum Technology Conference

acquisition, amplitude, conditioning, correction, estimation, grid, information, international petroleum technology conference, interpolation, matching, migration, navigation data, reprocessing, Reservoir Characterization, seismic survey, technical challenge, thailand super cube, time shift, Upstream Oil & Gas

Country:

Asia > Vietnam > Gulf of Thailand (0.45)
Asia > Thailand > Pattani > Pattani (0.45)
Asia > Thailand > Gulf of Thailand (0.45)
(3 more...)

Genre: Overview (0.87)

Geophysics:

Geophysics > Seismic Surveying > Seismic Processing (1.00)
Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.91)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
(2 more...)

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)

Technology: Information Technology (1.00)

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Evaluation of Factors in Horizontal Well Recovery in the Pattani Basin in the Gulf of Thailand

Harr, Michael Scott (Chevron Thailand E&P Ltd) | Chokasut, Siriporn (Chevron Thailand E&P Ltd) | Bhuripanyo, Chanapol (Chulalongkorn U.) | Viriyasittigun, Pattra (Chevron Thailand E&P) | Harun, Abd Rahman (Chevron Corp.)

OnePetroNovember, 2011

Abstract The Gulf of Thailand (GoT) is south of Bangkok. The pay interval typically covers 3000 to 5000 vertical feet. It is composed of a series of stacked fluvial point bars sands that have limited areal extent. In addition, normal faulting breaks them up further. Because all 40 acre wells will be drilled at some point, the justification for drilling a horizontal well is based on incremental recovery over vertical wells. In 2010, a team was assembled to look at establishing a common method to evaluate horizontal wells. Production results from horizontal wells were compared to vertical wells. Concept models were used to evaluate different factors in horizontal well recovery. Where available, history matched simulation models were used to compare horizontal to vertical wells. In addition, the team looked at factors in horizontal well performance. The team collected information on all wells drilled. The team looked for relationships to EUR and recovery factor. Then, the team took a more in depth study of the best horizontals and the worst horizontals. The overall recovery factor averages 20% for horizontal wells and 12.5% for an equivalent vertical well. The average incremental is 7.5%. There are three sources for this difference. The first is improved areal sweep efficiency of a horizontal well. The second is lower abandonment pressure with deep gas lift valves than with a vertical well. In looking at the best and worst performing horizontal wells, the poorer wells were in small reservoirs, often drilled very close to contacts and some were drilled into depleted reservoirs. The best wells were drilled in large very continuous reservoirs and often had strong reservoir drive (either water drive or gas cap expansion). Description The Gulf of Thailand (GoT) is south of Bangkok. Figure 1 is a map of the Gulf of Thailand. The pay interval typically covers 3000 to5000 vertical feet. It is composed of a series of stacked fluvial point bars sands that have limited areal extent. In addition, normal faulting breaks them up further. The overall development strategy is to drill wells on equal spacing (40 acres) on the high side of the faults to encounter as many sands as possible. Figure 2 illustrates the stratagraphic and structural complexity. Chevron has drilled over 80 horizontal wells in the GoT with an average of about 5–10 every year. The targets are oil reservoirs that are at least 25 feet thick. By nature of the depositional and structural setting, these are relatively small reservoirs, usually with OOIP between 0.7 to 6.0 MMBO. The sands can have both a GOC and an OWC. Because all 40 acre wells will be drilled at some point, the justification for drilling a horizontal well is based on incremental recovery over vertical wells. Because the horizontal well design and execution plans are typically developed during the same drilling programs of vertical wells, a quick and reliable method of horizontal well evaluation is needed. In 2010, as part of the Reservoir Management Framework, a team was assembled to look at establishing a common method to evaluate horizontal wells. As part of this initiative, the team looked at factors in horizontal well performance. The study also included a comparison to vertical wells. The team used a multi faceted approach. Production results from horizontal wells were compared to vertical wells. Concept models were used to evaluate different factors in horizontal well recovery. Where available, history matched simulation models were used to compare horizontal to vertical wells.

OnePetro

doi: 10.2523/IPTC-14981-MS

IPTC

IPTC-14981-MS

International Petroleum Technology Conference

abandonment pressure, Directional Drilling, drilling operation, Gulf, horizontal well, Horizontal Well Recovery, incremental recovery, international petroleum technology conference, Modeling & Simulation, Pattani Basin, Performer, poorest performer, recovery factor, reservoir, Thailand, Upstream Oil & Gas, vertical well, well planning

Country:

Asia > Thailand > Bangkok > Bangkok (0.45)
Asia > Vietnam > Gulf of Thailand (0.41)
Asia > Thailand > Pattani > Pattani (0.41)
(4 more...)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
(2 more...)

SPE Disciplines:

Well Drilling > Well Planning (1.00)
Well Drilling > Drilling Operations > Directional drilling (1.00)
Reservoir Description and Dynamics (1.00)

Technology: Information Technology > Modeling & Simulation (0.56)

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Time Lapse Neutron Logging Improves Formation Evaluation and Reduces Rig Time in the Gulf of Thailand

Logan, James P. (Chevron Asia South) | Whittlesey, Karen (Chevron Corp.) | Rossiter, Huw David (Halliburton Energy Services)

OnePetroAugust, 2009

Abstract In Chevron's Gulf of Thailand (GOT) operations, costs drive logging and formation evaluation. Programs for logging and evaluation are based on consideration of perceived value and the potential for comprehensive utilization. Well lifespan is short, and economics rarely provide for the use of higher technology at non-discounted prices. A recent business initiative recognized that oil vs gas fluid identification from logging measurements was a risk that should be mitigated providing a major opportunity to add value. Historical experience has shown, that the diameter of invasion can be greater than twenty inches by the time a well is logged with wireline which is beyond the limits of investigation for density and neutron tools, rendering the interpretation of fluid types ambiguous in most hydrocarbon bearing sands in this basin. To reduce this uncertainty, comprehensive wireline formation pressure programs have been run to assess hydrocarbon gradients but because sands are thin and permeabilities are low these programs have had various degrees of success. LWD (logging while drilling) neutron tools can obtain data prior to invasion. Overlaying the LWD neutron and wireline neutron reveals time-lapse differences between the logs, shows gas intervals, and confirms liquid-filled zones. The technique can also infer inflow permeability for some of the more shaley gas reservoirs. Positive fluid identifications have been confirmed by follow up wireline pressure gradients, NMR logs, and production tests. This paper will show many great examples of the evolution of a good idea. It will also demonstrate the effective use of technology, the buy-in from drilling engineers, and value of information benefits to the asset teams. Logging programs in the GOT once thought to be static, have rapidly evolved with insightful technology and the demonstration of its value. Geology Overview GOT Chevon's GOT operation is focused within the Pattani basin which is located near the geographic center of the Gulf of Thailand containing in some areas greater than 25,000 ft of almost entirely non-marine fluvial and delta plain sediments. The basin is characterized as a primarily north-south trending extensional system with virtually no evidence of subsequent inversion. Accommodation with control from basement block faulting has enabled the formation of en echelon graben systems resulting in a multitude of fault related structural and stratigraphic closures. Significant amounts of gas and liquid hydrocarbons have migrated into these horst and graben structures from localized coal and lacustrine source rocks. The fluvial depositional systems that provide the ubiquitous reservoir rocks in the basin developed on an extensive delta plain throughout the Neogene. Meander belts and associated point bars occasionally stack to form thicker reservoir units but sands are generally thin (less than 20 ft) and have relatively small accumulations (column and area) of hydrocarbon (Crossley. 1990). The key success of the drilling campaigns is to locate as many of these accumulations with one well, and comingle the reservoirs of known gas and lift the liquid hydrocarbons with single gas accumulations. To accommodate this strategy identifying the producible hydrocarbons and more importantly the hydrocarbon type within the multiple reservoirs found in a given well that may or may not be correlated to the offset wells is critical for success. Misidentifying the fluid type has led to difficulties in correlation as well as numerous missed opportunities to capture the reserves in a given well using the most effective completion methods. The technology described below has been of great assistance in Chevron? s operation to mitigate this risk.

OnePetro

doi: 10.2118/123320-MS

SPE

SPE-123320-MS

Asia Pacific Oil and Gas Conference & Exhibition

Country:

Asia > Vietnam > Gulf of Thailand (0.24)
Asia > Thailand > Pattani > Pattani (0.24)
Asia > Thailand > Gulf of Thailand (0.24)
(3 more...)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
(2 more...)

SPE Disciplines: Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)

Technology: Information Technology > Sensing and Signal Processing (0.34)

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Rapid Planning and Execution of the First Multilateral Well in the Gulf of Thailand: Results and Lessons Learned

Upchurch, Eric R. (Chevron International E&P) | Dooley, Paul A. (Chevron Corp.) | Hall, Kenneth H. (Chevron Thailand E&P Ltd) | Laohaburanakit, Songklod (BJ Services Intl.) | Maroongroge, Vichai (Chevron Thailand E&P Ltd) | McKee, Douglas (Chevron Thailand E&P Ltd) | Nucharoen, Panaratn (Chevron Thailand E&P Ltd) | Wagner, Michael R. (Chevron Thailand E&P Ltd)

OnePetroJune, 2008

Abstract In early 2006, Chevron International E&P drilled and completed the first multilateral well in the Gulf of Thailand. Routine development drilling in the Kaphong field of the Pattani basin unexpectedly discovered two production horizons that possessed reservoir characteristics and sufficient oil reserves to make each a viable horizontal-well candidate. At the time, however, only a single drilling slot was available on the platform; thus, dictating that only one wellbore could be drilled to tap both reservoirs. Further complicating the problem was that the drilling rig that discovered the horizons would be moving to a new platform 5 weeks after it was understood by reservoir engineers, geologists, and geophysicists that multiple horizontal-well candidates existed. This paper chronicles the rapid processes that took place to evaluate, plan, and execute the first multilateral well in the Gulf of Thailand. More importantly, this paper captures the unintended consequences (both good and bad) that came with executing this project so quickly. This includes an analysis of how decision making, project planning, and ultimate execution where affected by the short time window available. From this, we discuss lessons learned that may be universally applicable when rapidly expanding the use of technology in a remote region of the world (regardless of how small that expansion is). Introduction The Pattani basin in the Gulf of Thailand is a region containing significant oil and gas reserves. Chevron Thailand has been producing from this basin since 1981. Although predominantly a gas-producing region, the northern sector of the Pattani basin is oil-rich and has been the focus of significant development in recent years. The push for greater oil development has lead to sizeable production increases in the last 4 years. One key component to these production gains is the use of horizontal wellbores. Although only 20 standalone horizontal wells had been drilled before drilling the multilateral well discussed in this paper, they collectively contribute 11% of the 107,000 bbls/day oil production from Chevron's Gulf of Thailand operation while making up only 4% of the well count. With the strength of their oil-rate contribution, it makes sense that Chevron Thailand would want to drill as many horizontal oil producers as geologic reality would permit. It is within this setting that Chevron Thailand unexpectedly found two pay zones atop each other (separated by, 400 ft true vertical depth (TVD) that were both legitimate candidates for development using horizontal wells. This discovery occurred in February of 2006 while drilling a series of 20 nonhorizontal oil wells from the Kaphong Delta satellite production platform (KPWD) within the Kaphong oil field. The problem, however, at the time of this discovery is that only one of the 20 available drilling slots was still undrilled, thus forcing a difficult choice to be made. Do we stay within our currently well-defined technology-knowledge envelope and drill a single-horizontal wellbore, leaving one of the two producing horizons fallow until it can be drilled at a later date from an abandoned drilling slot? Or, do we step slightly beyond our local experience base and attempt drilling a multilateral wellbore to immediately maximize the oil-rate potential presented by these two producing horizons? Given ample time, all the necessary engineering steps for making this decision can be performed to arrive at a logical and well-defined solution. In this instance, however, time was not abundant. From the time it was understood that two economically viable horizontal-well targets existed, only 5 weeks remained before the drilling rig must either spud this well or move to another platform. This, in turn, compressed the time window for deciding how to proceed with this project to only 2 weeks, allowing the balance of time for appropriate predrill engineering and operational planning. In the end, the first multilateral well in the Gulf of Thailand was successfully drilled, completed, and put on production—but not without its share of difficulties and missteps. Implementing a technological step forward (even if it is a small one) is never without risk. Introducing such a step into a new country or region can only add to the possible risks. But doing it in a compressed time frame (though necessary in some cases) certainly introduces the greatest risk. From project inception to final completion, the team tasked with drilling this well understood this fact. Time limits, though, demand that trade-offs be made between execution readiness and planning completeness, with some of those trade-offs being unintended. The purpose of this paper is to describe the intended and unintended trade offs that occurred, their overall impact on the project, and how they relate to the environment in which this project was conceived and implemented.

OnePetro

doi: 10.2118/103941-PA

SPE

SPE-103941-PA

SPE Drilling & Completion

Country:

Asia > Vietnam > Gulf of Thailand (0.65)
Asia > Thailand > Pattani > Pattani (0.65)
Asia > Thailand > Gulf of Thailand (0.65)
(3 more...)

Geophysics: Geophysics (0.88)

Industry: Energy > Oil & Gas > Upstream (1.00)

Oilfield Places:

North America > United States > Alabama > Black Warrior Basin (0.99)
Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
(5 more...)

SPE Disciplines: Well Drilling > Drilling Operations > Directional drilling (1.00)

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Abstract A new array induction tool was recently developed for use in hostile environments. This 3.125-in. diameter tool is rated to 30,000 psi of pressure and 500°F (260°C) of temperature. A central improvement in this tool is the implementation of a new temperature correction scheme that uses multiple temperature sensors. This scheme is based on the use of the temperature and temperature derivatives with respect to both space and time. The correction reduces the temperature errors and helps to maintain accuracy over the entire temperature range. The transmitter/receivers spacing were designed to minimize the use of radial extrapolation in the generation of the standard radial curves (10, 20, 30, 60, and 90 inches). In addition, improvements to the calibration procedure, skin effect correction, and borehole correction algorithms were implemented. Finally, two dimensional software focusing algorithm was incorporated with an inversion algorithm that produces Rt, Rxo, and Dia. This paper provides an introduction to the tool and a discussion of its application in hostile environments. It also includes field logs from several hostile wells to illustrate the increased effectiveness of this new tool over the previous generation technologies in the identification and evaluation of productive zones. Introduction In 2006, Halliburton?s new array induction tool, the ACRt was deployed. In the ACRt design, a close association between sub-arrays position and the computed radial curves leads to radial profiles closely associated with the measurements. In this way, the results are less prone to distortions that may be generated by interpolation-extrapolation schemes. In addition, improvements to calibration, temperature correction, skin effect correction, and borehole effect correction were incorporated. By appropriate selection of materials and the use of a flask to protect the electronics, the same design has now been implemented in a hostile environment package, the new Halliburton hostile array induction tool: the H-ACRt tool. The HACRt tool improves over our previous hostile induction tool, the HDIL-A, a dual induction and short normal combination. The H-ACRt tool hardware and processing software are described in the first part of this paper. The temperature correction method, which is well suited for the demands of the hostile environment, is explained in some detail. Xiao et al. 2006 explains in comprehensive detail the calibration procedure, skin effect correction, borehole correction, software focusing algorithm, and radial inversion algorithm, which are used in this tool. To illustrate the advantages of the H-ACRt tool, a series of log examples from the Pattani basin in Thailand are included. The main advantages of the H-ACRt, higher resolution and improved characterization of invasion profiles, are demonstrated in these logs. The higher resolution of this tool helps to identify pay sands with thicknesses of less than 5 ft, which are not uncommon in this area. Sonde configuration The H-ACRt sonde is composed of one transmitter and six sub-array receivers with targeted depths of investigation of 10, 20, 30, 60, and 90 inches. Each sub-array antenna is made of a pair of coils, a main receiver coil, and a bucking receiver coil.

OnePetro

SPWLA

SPWLA-2007-EE

SPWLA 48th Annual Logging Symposium