Michael, Lester Tugung (Schlumberger) | Lajim-Sayung, Colinus (PETRONAS Carigali Sdn. Bhd) | A, Maisarah Bt. Jamaludin (PETRONAS Carigali Sdn. Bhd) | Ghazali, Rohaizat (PETRONAS Carigali Sdn. Bhd) | Gilbert, Rayner (PETRONAS Carigali Sdn. Bhd) | Sepulveda, Willem (Schlumberger) | Busaidy, Adil (Schlumberger) | Vaca, Juan Cortez (Schlumberger) | Zubbir, Ahmad Uzair (Schlumberger)
Perforation is a key component in a reservoir inflow to recover the most oil production from a reservoir. In Field S, perforating is typically conducted using the principle of overbalanced technique, which is commonly used in the oil and gas industry and is known to result in higher total skin. This paper discusses the first application of a thru-tubing stand-alone dynamic underbalance technique to clean up perforation tunnels in Field S, Malaysia. The dynamic underbalance(DUB) concept creates a rapid drawdown in front of existing perforation intervals to effectively clean up plugged perforation tunnels, thereby reducing perforation skin and increasing the productivity of the wellbore. The plunge in the oil price in 2014 has led to a focus on cost reduction and opex optimizationin production enhancement initiativesin Field S from existing well stock inventory. Through this initiative, two strings (Well XS and XS) have been selectedto increase perforation efficiency via thru-tubing DUB application, as part of the cost optimization in our production enhancement portfolio. The project scope covers a fullcycle production enhancement initiative, starting from candidate selection to job design and preparation, job execution and post-job analysis.
Khor, Y. Y. (PETRONAS Carigali Sdn. Bhd) | Shrivastava, S. K. (PETRONAS Carigali Sdn. Bhd) | Borhan, N. A. (PETRONAS Carigali Sdn. Bhd) | Baghdadi, F. (PETRONAS Carigali Sdn. Bhd) | Motaei, E. (PETRONAS Carigali Sdn. Bhd) | Kadir, Z. (PETRONAS Carigali Sdn. Bhd) | Supaat, S. F. (PETRONAS Carigali Sdn. Bhd) | Anasir, N. (PETRONAS Carigali Sdn. Bhd) | Mithani, A. H. (PETRONAS Carigali Sdn. Bhd)
Material balance analysis, a primary engineering technique, is an indispensable tool used for understanding the production performance and field management of mature gas reservoirs. Compilation and analysis of pressure-production data together with acomprehensive geological understanding including in-place hydrocarbon volumes and inter-block communication are prerequisites for material balance analysis. Deviation of observed P/Z data away from a straight idealised line necessitates further study, as it often indicates erroneous estimates of participating in-place volumes, aquifer support or reserves. Lack of pressure measurements, questionable stratigraphic correlations and uncertainty surrounding aquifer propertiesor reservoir connectivity highlight the requirement for further evaluation.
The objective of study is to develop a multi-tank material balance modelfor a mature, heterogeneous and compartmentalised carbonate gas field. Ultimately, the model must besufficiently robust to elucidate the field's production mechanism and optimise future field-development opportunities.
In this field, the pressure production behavior can be divided into two trends, an early rapid declining pressure trend, followed by a stabilised gradual pressure decline. Owing to higher drawdown in the field's early production life and insufficient recharging, the quick pressure decline underestimates the initial in-place gas volume. This volume is not adequate to support the sustained gas production rates observed in later years. This observation required further detailed analysis regarding the nature of zonal communication across adjacent reservoir intervals to better understand the production behavior of development wells during the design of the material balance model.
This paper discusses a study in which material balance analysis is coupled with multi-field network models. Implementation of this workflow can be usedto drive subsurface developmentsin a relatively short period.
Production data analysis (PA) refers to all analytical approaches and tools to reveal reservoir properties, performance, and characteristics such as material balance, Flowing Material Balance (FMB), Pressure Transient Analysis (PTA), Rate Transient Analysis (RTA), Decline Curve Analysis (DCA) and deconvolution. PA provides robust information comprising reservoir container volume, depletion mechanism, reservoir connectivity and well performance. It provides the best view on reservoir performance and helps to characterize the reservoir to understand reservoir quality, boundaries and flow characteristics to develop and optimize current reservoir management prior to any dynamic modelling. In this paper, the focus will be on analytical methods such as Rate Transient Analysis (RTA), Flowing Material Balance (FMB), Pressure Transient Analysis (PTA) and analytical simulation as an integrated approach for enhanced production data analysis in Gas fields. The idea of FMB has been introduced by L. Mattar (1997) and it is generally applied to determine oil or gas in-place using flowing pressure data (L.
Prasertamporn, Praisont (PETRONAS Carigali Sdn. Bhd)
Conductor jetting has been the preferred installation method for deepwater drilling. This type of installation depends on the skin friction between the conductor and the formation, making axial load capacity the critical success factor. Failure of axial load resistance causes well subsidence, incurring high cost in a deepwater environment. In principle, a longer conductor length gives higher axial capacity.
The PSC Company has drilled deepwater wells in East Malaysia and plans to drill more wells in the future. The conductor was designed using the same parameters as the nearby fields and the historical data. In addition, third-party companies normally perform conductor analyses based on the Gulf of Mexico soil set-up rate, which is not similar to East Malaysia. These practices have inadequate theoretical support and could lead to failure.
The paper objective is to analyse the conductor length requirement for East Malaysia with The PSC Company's planned conductor. The analysis includes the conductor length requirements for different well parameters.
The soil profile was derived from the nearby field soil-boring data and previous well parameters to obtain the soil set-up curve. The soil profile was matched with various parameters to analyse the required conductor length. The result describes the significant effect of conductor and jetting bottom hole assembly weight. Higher weight gives more weight on bit, providing high immediate capacity and requiring a shorter conductor. In addition, setting long 20" casing imposes a higher load that requires a longer conductor. However, PAD mud weight and duration before land weight on the conductor do not provide a significant effect. Moreover, other conductor specifications that may be run in the future were analysed, showing the same tendency, where a heavier conductor requires a longer conductor.
This analytical method can be recalibrated for other conductor configurations in the future.
The information contained herein is provided with the understanding that the COMPANY makes no warranties, either expressed or implied, concerning the accuracy, completeness, reliability, or suitability of the information.
Geological interpretation based on the seismic attributes can enhance the accuracy of the interpretation. According to
Hung, Barry (CGG) | Wang, Xusong (CGG) | Phan, Ying Peng (CGG) | Alai, Riaz (PETRONAS Carigali Sdn. Bhd) | Xin, Kefeng (CGG) | He, Yi (CGG) | Rahman, Nurul Nadzirah (PETRONAS Carigali Sdn. Bhd) | Tang, Wai Hoong (PETRONAS Carigali Sdn. Bhd)
Recent efforts in marine broadband processing have largely been focused on source and receiver deghosting. To fully recover the frequency bandwidth of seismic data, the anelastic nature of the earth needs to be taken into account. In addition, in the presence of gas anomalies, attenuation of seismic waves will cause further degradation in the resolution of migrated images. By quantifying the attenuation of seismic energy using quality factor Q, we can model the intrinsic absorptive nature of the earth as background Q and the localized absorptive bodies, e.g. gas pockets, as anomalous Q. Using the frequency information and the amplitude information of the data to estimate the background Q (FS-QTomo) and anomalous Q (A-QTomo), respectively, the attenuation effects of the earth can be compensated by the application of Q-PSDM in the presence of gas with the resultant combined Q model. The accuracy of these processes is further enhanced by broadband processing with deghosting in terms of better estimation of the centroid frequency for FS-QTomo and deeper penetration of low frequency signal through the gas bodies for A-QTomo. Thus, the interplay of deghosting and Q tomography provides a full broadband processing workflow for restoring the distortion of amplitude, frequency and phase caused by the combined effects of the earth’s anelasticity and gas pockets. We applied our workflow on a field data example and demonstrated through this first case study that high resolution broadband seismic data with improved signal to noise ratio (S/N) can be obtained.
Extending the usable frequency through broadband acquisition and processing has proven to be beneficial in the application of FWI (Ratcliffe et al., 2013), the enhancement of imaging (Zhou et al., 2014), studies of inversion (Soubaras et al., 2012), etc. In the area of broadband processing, one of the key steps is deghosting. In recent years active research has been conducted into both pre-migration and post-migration deghosting algorithms, as well as its application to different marine acquisition configurations, e.g. conventional shallow cable, variable-depth cable, multi-component cable etc.. For full broadband processing, however, the attenuation effects of the earth’s subsurface need to be taken into account. To this end, the intrinsic anelastic nature of the earth must be considered in the processing workflow. Moreover, in the presence of gas, both as shallow pockets and as commercial reservoirs (not an uncommon geological setting in many parts of the world), localized strong absorption from these gas bodies will cause amplitude dimming and frequency dependent dissipation, and this degradation in signal needs to be recovered.
This study examines the methodology of the packer-probe wireline formation tests (WFT) to interpret and analyse the pressure transient data acquired at the packer and probes along the wellbore for single layer and multi-layered systems. Such tests are often called WFT interval pressure transient tests or simply WFT IPTTs. IPTTs offer some advantages over the conventional (extended) well tests in terms of cost, time, and providing important properties such as horizontal and vertical permeability over a scale larger than cores but smaller than that of extended well tests. In this project, the same methodology applied to a packer-probe WFT in single layer system will be applied to various multi-layered systems to investigate the feasibility and validity of using the single-layer analysis methodology for the WFT IPTTs conducted in multi-layered systems because only a few of researchers have considered interpretation of packer-probe interval pressure-transient tests in multi-layered systems. Thus, one of the main objectives in this study is in detail to access the methodology used for analyzing a single layer system and apply the same to multi-layered systems. Various averaging formulas of horizontal and vertical permeabilities will be used to represent a multi-layered system. The validity of the representation is tested through pressure response matching. The results show that an “equivalent” single-layer analysis based arithmetic averages of the horizontal and vertical permeability can be used to analyze the IPTTs acquired in multi-layered systems provided that the heterogeneity is not large (i.e., Dykstra-Parsons coefficient is less than 0.4 for spherical flow analysis and is less than 0.06 for radial-flow analysis).
Wireline formation testing is a part of pressure transient testing methods. It is an evolution of DST, Drill Stem Test. DST usage is limited to the hole condition and the cost of repetitive runs of DST for formation evaluation. Thus, wireline formation tester is often used for formation evaluation work. This method is usually performed in an open-hole using a cable-operated formation tester with sampling module ability which is anchored down-hole while the communication is established by several pressure and sampling probes. The first tool was introduced in the 1950’s concentrated on fluid sampling. RFT (Repeat Formation Tester) is then introduced to add capability of the tool to repeatedly measure formation pressure in a single run into the well (Ireland et al. 1992). Since 1962, common applications of wireline formation tester are:
According to (Schlumberger, 2006), pressure transient tests are conducted at all stages in the life of a reservoir; exploration, development, production and injection. During exploration stage, tests are conducted to obtain fluid samples and static pressures of all permeable layers of interest. These pressures can be used to obtain formation fluid gradient to identify fluid contact in the reservoir. During development stage, the emphasis is on static reservoir pressures, which are used to confirm fluid contacts and fluid density gradients. On that basis, the different hydraulic compartments of the reservoir will be determined and tied into geological model. During production stage, tests are for reservoir monitoring and productivity tests to access to need for stimulation.
Alai, Riaz (PETRONAS Carigali Sdn. Bhd) | Rahman, Nurul Nadzirah A. (PETRONAS Carigali Sdn. Bhd) | Phan, Ying Peng (CGG) | Wang, Xusong (CGG) | Wu, Xiang (CGG) | Abd Mutalib, Mohd Al-Amin B. (PETRONAS Carigali Sdn. Bhd.) | Bakar, Hairul Hafez (PETRONAS Carigali Sdn. Bhd.) | Beg, Mirza Arshad (PETRONAS Carigali Sdn. Bhd.)
Summary In this abstract we present some efforts that have been taken towards pushing the limits of seismic reprocessing and reviewing its valuable outcomes. Every now and then this question does come up - "Should we re-acquire or reprocess seismic data?" (with the objective of obtaining the most optimal seismic images so interpreters can come to confident conclusions prior to deciding well trajectories). When seismic data interpretation limitations are observed when reviewing processed "vintage" data, the main question to answer is: Would the latest state-of-the-art seismic data acquisition technologies solve all the imaging problems in comparison with reprocessing the same data? The main challenge in answering this question is how much can reprocessing (generally much lower in costs than reacquiring a new data set) of the vintage data contribute in reaching the objectives of the team of interpreters? In this abstract we review a few workflows and reprocessing efforts that have contributed significantly to improved seismic images for a case study offshore Malaysia.
A brown field producing mainly from two main reservoirs, currently experiencing low reservoir pressures and high GOR ranging 400-1000 psig and 2000-20000 scf/stb respectively with about 17% average water cut. Re-perforation and adding new perforations are one of the key production enhancements activities for this field.
Two candidates were identified for additional perforation opportunities. Nodal analysis evaluation study based on reservoir parameters (permeability, water saturation, reservoir thickness) suggested oil can be gained by executing these opportunities.
The main issue in executing the perforation job was that the proposed perforation intervals are covered by 3 barriers which are the 2-3/8”tubing, 7” and 9-5/8” casing. Technical simulations and practical surface tests were performed to verify the integrity of the 2-3/8” tubing, and when shooting in multiple casings (7” Liner and 9-5/8” Casing). These tests were done to select the proper gun type, size and phasing (shot density) due to the limitation and risks associated with the through tubing perforation. The gun selected after the study was 1-11/16” strip gun with 2 SPF and 0 deg phasing.
The through tubing additional perforation jobs were executed with 20 ft and 135 ft for the two highly deviated (60-70 deg) candidate wells. These were the first job for PETRONAS Carigali in through tubing perforation through three barriers of tubing, liner and casing.
Very good results were achieved, where oil production increased by about 300 bopd and 200 bopd for the two wells respectively, and the WC% decreased from 45% to 0% for the first well due to higher reservoir pressure of the upper zone.
The successes of this application can enhance re-looking to many wells that have additional perforation ignored initially due to covering by tubing plus multiple casing which result in increasing oil production.
This paper shares the details of the well, the nodal analysis carried out to quantify the possible gain, the preparation for the yard tests and the evaluation in the gun selection.
Chandola, Sandeep K. (PETRONAS Carigali Sdn. Bhd) | Velayatham, Tayallen (PETRONAS Carigali Sdn. Bhd) | Foo, Low Cheng (PETRONAS Carigali Sdn. Bhd) | Tham, Michelle (WesternGeco) | Ho, Koon Hong (WesternGeco) | Mahmud, Nurhakimah (PETRONAS Carigali Sdn. Bhd) | Kumar, Subodh (PETRONAS Carigali Sdn. Bhd) | Teck, Law Chung (PETRONAS Carigali Sdn. Bhd)
The survey was located in offshore Sabah in water depths ranging from 50 to 300m. The legacy conventional 3D streamer data, acquired in 2001, suffered from poor imaging in the zone of interest over a significant portion of the survey (Figure 1). A combination of factors such as complexity of the subsurface structures, inadequate illumination due to conventional narrow-azimuth legacy acquisition, and low energy penetration through the monotonous shale in the overburden, all contributed to the poor data in the area. Two wells were drilled in the good data areas with hydrocarbon discoveries; however, the seismic data between the wells is low in signal-to-noise ratio and very poor in image quality. This poor data zone is named "Black Pond" due to the lack of reflection continuity, difficulties encountered during interpretation and delineation of the reservoir. The depth imaging of a subset of legacy data in the survey area also failed to produce any significant improvement in the data quality. Several other areas in Malaysian basins suffer from similar imaging challenges.