Baker Hughes drilled one horizontal well for major Indian operating company in a, low resistivity contrast field, onshore India. The candidate field / basin is a proved petroliferous basin, located in the northeastern corner of India.
The scope of work for this project involved integrating geological and open hole offset parameters to build a Geosteering model. Integrated data included a study of offset well data from the field, regional and local dip analysis from wellbore images, and a review of structural maps. Successful integration of these data helped to steer the well in the desired zone as per plan and make the best use of the data and to reduce uncertainties in Geosteering, drilling. Although high-quality 16-sector images commonly yield bedding dip, fracture and other geological information, this paper emphasizes how real-time reservoir navigation decisions was made using Geosteering modelling, real-time image processing, dip picking study etc.
Panna Formation is a very critical and challenging formation deposited during Paleocene time of geological past in various parts of Western Offshore Basin of India. It was deposited in a fluvio-deltaic environment, sometimes even in a restricted marine set-up. Such variation in depositional setting caused mineralogical complexity, which in-turn imposed a limitation in conventional approach of formation evaluation and saturation determination to identify the pay zones with confidence. A comprehensive approach of integrated formation evaluation for rock quality characterization was attempted using a combination of new generation elemental and acoustic analysis for delineating the potential hydrocarbon bearing zones independent of conventional resistivity-based approach along with a better insight on formation heterogeneity. The studied well was drilled up to Panna Formation and conventional open-hole logs were acquired while drilling. However, due to complex mineralogical nature of the formation, estimation of key critical reservoir parameters was very challenging and imposed higher uncertainties in the results. An alternate approach was adopted using a few advanced log measurements to address this challenge. A combination of new generation elemental and acoustic data has been recorded in a single wireline run after acquiring conventional basic logs while drilling. An accurate porosity was derived by eliminating various mineralogical assemblages along with estimation of a geochemical permeability based on detailed elemental analysis. Measured aluminum from neutron inelastic capture spectrum method enabled to estimate clay volumes with accuracy, which provided the required insight for better effective porosity in such shaly-sand environment. Based on this improved porosity and permeability, an approach for rock-quality indexing was used for reservoir delineation.
Moreover, a good amount of organic carbon was found associated with clays caused shales with higher resistivity. Based on elemental measurements an interesting insight was possible to extract for resistivity independent fluid saturation. An additional pay zone with hydrocarbon saturation based on such resistivity independent approach was possible to identify, which was masked by conventional resistivity-based interpretation. Acoustic analysis results assisted in delineating the zones with possible open fractures to avoid any possibility for unwanted fluid breakthrough.
Based on this approach of alternate integrated petrophysical analysis perforation zones were selected including an additional zone, which was masked based on conventional analysis. The well was started producing around 1,05,000 m3 gas with around 200 barrels of oil per day. This study showcased an alternate and efficient characterization approach for any such mineralogically challenging clastic formations.
Easy oil is no longer low hanging fruit for oil and gas operators, and drilling targets are becoming increasingly ambitious, which results in escalation of the well trajectory complexity. This accordingly spirals the well and completion costs. To overcome this situation, technology must play a role to reduce cost, increase efficiency and ensure safety at all times. Conveyance is the key for any data acquisition and well completion activities. Historically, conveyance methods for data acquisition and perforation in highly deviated or horizontal wells required drill pipe or coiled-tubing methods. These methods are time consuming, labor intensive, require a larger equipment footprint, with possible HSE risks involved. Mubadala Petroleum in Thailand has seen a significant increase in horizontal and high deviated wells over the past few years. The wireline tractor technology has been used for the first time in Mubadala Petroleum's Thailand operations during the drilling, initial completion and workover intervention operations, and it has been a game changer for Mubadala Petroleum in Thailand in terms of reducing rig time, well cost, and most importantly minimizing the HSE risks.
Over the past few decades, the oil and gas industry has developed the technique of drilling horizontally through the reservoir to maximize the surface contact area of the reservoir, to gain higher recovery and production. However, one downside from this technique is that it has become challenging and costly to perforate or to obtain measurements in this horizontal environment, as gravity will no longer support the wireline tools to reach to the bottom of the well. Wireline Tractor technology has played an important role to overcome this challenge. It reduces time, cost and will improve data quality as well as increase wellbore coverage. The wireline tractor functions with an electric over hydraulic power relationship, using its drive/wheel sections to push the passenger tool downhole as the cable is spooled off the unit allowing the tool to reach the end of horizontal or deviated wells without deploying drill pipe or coiled tubing conveyance methods. With this principle, any job that is typically run on electric wireline in a vertical well can be efficiently done in a horizontal or deviated well using wireline tractor.
Material presented in the paper will be from actual operations, examples being tractor conveyed wireline logging tool and 4.5in Outer Diameter (OD) 90 ft heavy long perforation gun in single tractor operations. It will also display the operational efficiencies increases and risk reduction being obtained.
Amer, Mohamed Mostafa (ADNOC Offshore) | Serry, Amr Mohamed (ADNOC Offshore) | Afzal, Nusrat Afrin (ADNOC Offshore) | Al Zaabi, Fatema (ADNOC Offshore) | Al Jaberi, Salem (ADNOC Offshore) | Zhou, Jiheng (Baker Hughes, a GE Company) | Ismail, Mostafa (Baker Hughes, a GE Company) | Nada, Al Sayed (Baker Hughes, a GE Company)
Pulsed neutron logging is currently the most commonly used technology for cased hole formation saturation analysis, providing data for reservoir monitoring and management. The common pulsed neutron log measurement is the formation capture cross section (Sigma). The data can be logged at a relatively fast logging speed. Water saturation analysis using the Sigma log requires high porosity and known formation water salinity. Errors in the Sigma log interpretation can result from the uncertainties of water salinity values, which usually change, for example, due to mixing of the hypersaline formation brine with the low-salinity injected seawater. Heterogeneity and changes in the carbonate petrophysical properties also play a role in magnifying the magnitude of water salinity changes. Carbon/ oxygen ratio logging (C/O) is salinity-independent and can be applied to overcome the problem, but the physics of the measurement usually require multiple passes with lower logging speeds than Sigma logging. This paper introduces a novel pulsed neutron logging methodology to help overcome the mixed-water salinity problem and produce a reliable water saturation interpretation for updating fluid front maps.
First, the pulsed neutron tool was operated in Sigma mode to cover the full target reservoir interval in a single pass. The tool was then switched to the C/O mode with multiple passes for 50ft only at the top of the target reservoir. Monte Carlo modelling was applied to the C/O data to calculate the water saturation. The C/O result was then used with the Sigma log data to inversely calculate the Sigma water using a Sigma-based material balance equation across the same interval. The final water saturation across the full interval was estimated by using the calculated water salinity and the Sigma data.
Through the application of the proposed methodology, we successfully measure the target formation saturation information in an acceptable operating time, when compared to conducting the conventional C/O logging across the full interval. The results show that the estimated formation water salinity is close to that value of drilling mud filtrate; the water saturation is slightly lower than that from the openhole resistivity interpretation.
This paper introduces how to optimize a pulsed neutron logging program that combines the C/O and Sigma measurements to enhance the offshore operations efficiency, minimize the water saturation interpretation uncertainties, and support future field development planning.
Ngo, H. (PTTEP Geology) | Chommali, P. (PTTEP Geology) | Charucharana, T. (PTTEP Geology) | Rattanachan, S. (PTTEP Drilling) | Ung-Aram, K. (PTTEP Drilling) | Tangkaprasert, P. (PTTEP Drilling) | Thiangtham, C. (PTTEP Drilling) | Pinprayong, V. (Weatherford Wireline Services)
The Sirikit field is a mature reservoir located in the Phitsanulok Basin in north-central Thailand. The field produced first oil in late 1981. Typical logging programs include a complete set of openhole (OH) logging suites such as a triple combo, including gamma ray-neutron-density-resistivity, or quad combo including gamma ray-neutron-density-sonic-resistivity. The reservoir production and injection are carried out with commingled completion. Therefore, wireline formation testing, and sampling tools are usually included for acquisition.
Development wells with highly deviated trajectories pose challenges to conventional wireline logging (WL) operations, especially in deep wells exceeding 3,000m. In sections with high dogleg severity, the tools are prone to sticking, and the cable can become key-seated due to hole conditions, deviation, washouts or caving.
Log data is a vital component for studying geological complexity, completion and production planning. Therefore, there is a need for an alternative method to convey WL tools to reach the bottom of the hole. In 2015, an alternative conveyance method called "through drillpipe logging" (TDL) was proposed to mitigate the risk of WL tools sticking or hanging up in an openhole environment. This method uses a slim-chassis, 2.25 in. outer diameter (OD), WL logging suite that enables the tool to be run through the drillpipe. The first TDL job was trialed in Thailand in May, 2016 as the second run after the WL run hung up. This TDL run hosted a full triple-combo suite and WL formation testing tools, which reached total depth (TD) while overcoming hole-condition issues that had been experienced during the first run. Following this successful log run, the TDL has become the preferred contingency planning option to support WL operations in challenging wells. To date, a total of 64 jobs, including triple combo (TC), quad combo (QC), formation testing & sampling (FTS) and cross-dipole sonic (CDS) have been executed successfully with less operating time than conventional contingency processes involving wiper trips, tool pushing, or pipe conveyed logging. This track record confirms that TDL provides a fit-for-purpose solution for logging in challenging conditions.
Kleawyothatis, T. (Weatherford KSP Limited) | Pruimboom, J. (Weatherford KSP Limited) | Dendandome, S. (Chevron Thailand Exploration & Production, LTD) | Pisarnbut, N. (Chevron Thailand Exploration & Production, LTD) | Thipmongkolsilp, P. (Chevron Thailand Exploration & Production, LTD)
There is no longer a requirement to run wireline Triple Combo logs in deep, high temperature wells. A joint development project has successfully delivered the world's first high-temperature M/LWD Triple Combo suite rated for 200°C [392°F]. Results to date are compared with previous performance in the Gulf of Thailand (GoT).
The new suite required a ground-up redesign of printed circuit board (PCB) electronics in order to meet the temperature qualification criteria of 200 hours at 200°C [392°F], with a survivability of 210°C [410°F] for four hours. The suite's sensors were developed in two phases, each with four milestones, over a period of 36 months. Initial rigorous thermal qualification was followed by harsh thermal vibration qualification testing routines. Several PCB redesigns were required in order to finally pass this testing. Ultimately, five prototype triple combo suites of tools were delivered to Thailand, on time and on budget, for in-situ field testing.
M/LWD Triple Combo field trials commenced offshore in the GOT, in fields exhibiting some of the global industry's most demanding drilling environments with respect to high rates of penetration [and accompanying punishing levels of vibration], extreme temperatures and significant well complexity. Compared to adjacent platforms with similar wells in the most challenging field, the new suite, together with other drilling efficiency measures, played a pivotal role in helping to reduce average days per well over 50% a considerable improvement. To date, more than 475,000 ft [145,000 m] have now been drilled in 71 GoT wells using this Triple Combo M/LWD technology. Furthermore, the new high-temperature Triple Combo M/LWD tools have been one of several key contributing factors in establishing two notable drilling records: drilling the GoT's longest well at 17,559 ft [5,532 m] and the longest single-bit run in the production section at 8,952 ft [2,729 m], without any failures at a maximum temperature of 199°C [391°F]. The suite provides additional benefits such as the provision of real-time annular pressure while drilling.
With this feature, engineers can closely monitor the equivalent circulating density (ECD) an important parameter for avoiding kicks and losses at up to 200°C [392°F].
The proven step change in drilling efficiency arising from this joint development can be attributed to the elimination of temperature mitigation measures and Triple Combo wireline logging, the problems associated with acquiring the wireline data, and an overall improvement in drilling practices.
Kulananpakdee, K. (PTTEP) | Chommali, P. (PTTEP) | Ngo, Hien (PTTEP) | Pinprayong, V. (Weatherford) | Kloos, J. (Weatherford) | Ryder, I. (Weatherford) | Villamizar, C. (Weatherford) | Baca Espinoza, I. (Weatherford)
Drilling wells in complex geological structures from offshore platforms, or onshore in areas with land access restrictions often creates complex S-shaped wells. In many such wells, high-angle doglegs cause problems with wireline key-seating, thus restricting reservoir access. When Logging While Drilling (LWD) data acquisition is not an option and Pipe-Conveyed Logging (PCL) is discarded because of its risky and time-consuming nature, many wells could end up without critical Formation evaluation data.
To overcome reservoir access challenges in the Sirikit Field in Thailand, a Through-Drill pipe Logging (TDL) technique has recently been introduced to complete formation evaluation. This method safely and effectively overcomes the complex well trajectories and associated wireline conveyance problems, such as key-seating. Slim 2.25" OD logging tools including Triple Combo (TC), Quad Combo (QC) and formation pressure tester and fluid sampler are deployed on wireline through open-ended drill pipe into open-hole without difficulties and with full well control maintained at all times.
A standard TDL operating procedure has been developed between wireline and drilling crews, allowing for safe and fast operations. The driller is able to have well control, with pipe being reciprocated regularly. Typically the drill pipe is run with a reamer shoe to allow borehole cleanout operations in the same run. The TDL deployement method is now a key component in the standard decision tree for data acquisition strategy in Sirikit Field and it has been successfully introduced in the Sirikit Field in May 2016. Since then, a total of 59 runs have been performed in 31 wells where wireline reservoir access problems were encountered, saving an estimated 1,240 hours of combined rig time not counting any potential wireline fishing jobs that would likely have occurred. A near 100% success rate is maintained, measured by reaching well TD and acquiring all desired wireline data. Petro physicist and geologists are no longer left without the crucial formation evaluation data they require for successful reservoir management.
This paper present a case study that clearly demonstrates that the TDL deployment technique can be very effective in providing safe and efficient wireline access to reservoir sections in S-shaped wells with risky wellbore conditions, where high-angle doglegs and key-seating would otherwise have restricted the ability to obtain Formation evaluation log data and fluid samples.
Sand management is one of the key component of Bongkot production processes. Current sand production prediction is based on a model which requires sonic and density logs for all the wells. However, a combination of complex well architecture and focus on reducing well cost resulted in many wells not having acquired these important logs. This project has implemented new technique of "Artificial Neural Network" to solve this problem. Using this method, synthetic logs are generated to obtain the values of missing sonic and density data. These data are then used in the existing sand models to predict sand production potential.
This project was evaluated with three field cases. The sand failure predictions based on synthetic rock properties matched with actual sand production. Therefore, the sand prediction workflow has been updated to include log synthetic if acroustic or density log are missing.
Sarit, R. (PTTEP Drilling) | Nitipong, K. (PTTEP Drilling) | Kittichai, U. (PTTEP Drilling) | Iddhi, C. (PTTEP Drilling) | Phakphum, T. (PTTEP Drilling) | Nuttapornpat, T. (PTTEP Drilling) | Hien, N. (PTTEP Geology) | Prayuth, C. (PTTEP Geology) | Kanaporn, K. (PTTEP Geology) | Verapich, P. (Weatherford) | Irina, B. E. (Weatherford) | Damrongsak, C. (Weatherford) | Carlos, V. (Weatherford)
Modern drilling technologies enable to complete tremendous borehole trajectories, despite well control risks and unpredicted sticking issues. Nevertheless when it comes to formation sampling the development wells and deviated drains are excluded from the program due to high risk of getting stack with heavy logging suit. The high costs of rig time nowadays practically exempted drilling the pilot holes for PVT sampling acquisition and to reduce rig time as much as possible. Therefore, new technologies are demanded to enhance formation testing (FT) and sampling in deviated hole while mitigating the risks of getting stuck.
The Sirikit and Suphanburi fields are in different provinces of Thailand and usually required the complete set of open hole logging suit, including formation pressure and sampling. However some deviated sections are usually experiencing high wash out and solids key seating where no tools could pass through using the standard wireline (WL) conveyance technique. The only viable option in those cases is to run in hole with slim FT through drillpipe logging (TDL), that allow slimmer WL suits conveyance through drillpipe open-ended bottom hole assembly.
The slim FT is a 2.4" outer diameter (OD) tool with pump out and sampling capabilities. The tool was already tested in several jobs with WL and shows reliable results. Three wells with 8.5" section and up to 47 deg wellbore deviation were selected for testing the sampling TDL. This was a first trial as such in the entire Asia Pacific region. The end of drillpipe was positioned around 50m below the high inclination and dogleg severity zone to prevent WL from key seating. Once WL tool ran through drillpipe and engaging openhole, the entire string was moved to the pressure testing and sampling stations. Maximum allocated time of one hour per depth was sufficient for successful fluid identification and sampling. Due to articulated centralized design with single point contact with formation, no differential sticking or cable key seating were experienced during operation. The downhole real time monitoring was completed using the basic capacitance and resistivity sensors, which enable appropriately, distinguish between formation water and hydrocarbons during pump out and sampling. The sampling bottles were extracted on surface and verified the collected oil. The results of all cases were successful and fit for purpose.
Drilling deviated development wells are a world-wide established practice, however no slim sampling tool were available through bit. Drilling deviated wells are a world-wide established practice that post challenge to WL formation testing and sampling operation. The successful combination of through drillpipe logging method with slim formation testing and sampling WL tool opens the new horizon solutions for evaluation of the hydrocarbons in place without need to drill the pilot holes or redrill the damaged section.
Kulananpakdee, K. (PTTEP) | Chommali, P. (PTTEP) | Hien, N. (PTTEP) | Thiangtham, C. (PTTEP) | Juntamat, P. (PTTEP) | Lertsrisunthad, P. (PTTEP) | Prachukbunchong, P. (PTTEP) | Chantipna, D. (Weatherford) | Pinprayong, V. (Weatherford) | Villamizar, C. (Weatherford) | Baca, Espinoza I. (Weatherford)
Determining reservoir pressure and confirming fluid type in development wells is of major interest to many reservoir engineers. Because of the high costs and operational risks of having a wireline formation tester (FT) stuck downhole, operators seek reliable technologies that not only deliver the information they need but also mitigate the chances of losing the tool downhole. A new generation of slim, light-weight FT technologies can help make production-management decisions, especially in the often complex geometry of development wells.
The Sirikit field Onshore Thailand is an extensively faulted and heterogeneous reservoir, therefore continuously updated pressure profiles have become the key in refining reservoir models. Productive zones are typically thin, but highly permeable. Traditional open hole (OH) log evaluation is insufficient to distinguish fluid types and formation fluid identification (FID) is required in every zone before completion. Because wireline FTs often have thick bodies which are pressed against the borehole wall and sampling takes at least one hour of pump out, they present an increased risk of getting stuck.
A smaller diameter FT was evaluated whose body equally centralized in the well during a test in order to dramatically reduce the risk of differential sticking. However it was not clear whether the new tool could similarly distinguish between hydrocarbons and water in a synthetic based mud (SBM) environment using capacitance and resistivity sensors. Four wells with various trajectories and fluid types were selected to benchmark the new tool. Both traditional and new slim FTs were run in the hole (RIH), monitored in real time and the capabilities of the two tools were cross-checked against each other. The results showed that both tools required a similar pump out volume to reach a clean sample. Despite the oil-base mud environment, the slim tool was able to distinguish the transition from mud filtrate to formation hydrocarbons, and in wells where water-base drilling fluids were used, formation water could be similarly recognized. All water samples were directly drained at surface to verify the in-situ real time measurements and oil samples were sent to the lab. The results showed a remarkable consistency in most cases and during trial tests the slimmest sampling tool exhibited a tremendous value in the first stage of field development and it is continuously used nowadays in newly drilled wells.
A slim testing and sampling tool shows good reliability for basic fluid identification and is especially suitable for wells with differential sticking issues. Globally, this tool may provide a solution of future wireline pressure and sampling, which can help operators to make proper reservoir-management decisions, especially in complex geometry wells or challenging geological formations.