|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
Zulkifli, Nur Azah (PETRONAS Carigali Sdn Bhd) | Chisholm, Lisa Claire (PETRONAS Carigali Sdn Bhd) | M Yusoff, Amy Mawarni (PETRONAS Carigali Sdn Bhd) | Kosnon, Nur Khairina (PETRONAS Carigali Sdn Bhd) | Mohd Azkah, Mohd Zubair (PETRONAS Carigali Sdn Bhd) | M Diah, Mohd Amri (PETRONAS Carigali Sdn Bhd)
Abstract Reservoirs in MN Field comprise predominantly fluvial delta deposits. A number of reservoir modeling studies have been performed for major reservoirs, however, there are still challenges to be addressed. After 20 plus years of production, a project for minor reservoirs has been crafted based on the understanding and challenges of major reservoirs. The primary objective of this study was to improve the understanding of the uncertainties impacting the well performance and reservoir connectivity; and to find potential infill opportunities. A 2D conceptual modelling approach was used as a practical way to incorporate the static and dynamic data of logs, core, seismic and pressure data. Taking the lessons learned from the major reservoir performances, this study focused on the fluvial reservoir sedimentology to address and decrease the uncertainties through the different scales of heterogeneity. Consequently, depositional facies maps were developed with the integration of geophysical study and interpretation derived from seismic analysis. These integrated depositional facies maps were then further refined with the well production data and scenarios of multiple compartments from multiple iterations to fit into the conceptual models of this field. Refined paleo depositional maps for these minor reservoirs allowed for a better understanding on reservoir heterogeneities and further improved the geological understanding. This fundamental study can show us a more precise distribution and tendency of the sand and the scales of heterogeneity with different depositional facies. However, capturing and preserving the different levels of heterogeneities and compartmentalization is complex for some thin sand reservoirs which are below seismic resolution and have low correlation of reservoir properties-seismic response. Additionally, multiple compartments were inferred due to pressure difference and multiple contacts within a reservoir. This was further complicated by the uncertainty in log interpretation due to inadequacy of high confidence data (DST/fluid sampling), suppressed resistivity from shaly sands and below log resolution of thin beds. Despite of these issues and challenges, with integration of all the data available and rigorous team discussions; the minor reservoirs depo-facies, static and dynamic compartmentalization were finalized, leading to enhancement of reservoir prediction, communication and quality.
Ng, Khaiyi (PETRONAS Carigali Sdn. Bhd.) | Abdou Ali, Asem Mahmoud (PETRONAS Carigali Sdn. Bhd.) | Hanalim, Linda (PETRONAS Carigali Sdn. Bhd.) | Suwarlan, Wahyudin (PETRONAS Carigali Sdn. Bhd.) | Lee, ChunRhen (PETRONAS Carigali Sdn. Bhd.)
Abstract Reservoir compartments are segments that are effectively isolated by structural, sedimentologic or diagenetic barriers that hinder fluid flow laterally between compartments. However, in cases of sandstone reservoirs incising each other, the boundaries of the compartments are poorly defined and huge uncertainties are imposed on the connectivity and fluid flow behavior between them. Various geological and engineering approaches are used to work out the sand-to-sand juxtaposed reservoir compartments in Angsi Field offshore Peninsular Malaysia. In Angsi Field, located in the Oligo-Miocene Malay basin, the I35U and I35M sandstone reservoirs from Group-I stratigraphic unit (coastal-fluvial/deltaic lobes) provide a complicated case of areal and vertical reservoir compartments. The I35U channelized blocky sand incised into I35M mouth bar sand in some parts of the field. Mapping of the interlaced reservoir compartments of both reservoirs is based on conceptual geology, log patterns and seismic data. Although the vertical spacing of the two reservoirs is below seismic resolution, the difference in quality, thickness and fluid type have allowed seismic involvement in delineating compartments. To verify the geological findings, multidisciplinary team seeks out various methods to resolve connectivity uncertainty between the two reservoirs. Fluid gradients supported the idea; however reservoirs fluid contacts are sometimes leveled. Existing oil producers from both reservoirs provides reliable pressure-production data for classical reservoir engineering analysis. Production Decline Curves of both reservoirs vary significantly; seemingly controlled by internal depositional architecture of each reservoir. Depletion Plots further verify no lateral communication between the two reservoirs. Finally, Material Balance proves the understanding of communication between reservoirs; oil-in-place and reserves are aligned with geological studies. Two successful wells drilled lately based on findings from the above approach. A representative simulation model is being built for both reservoirs, incorporating the findings, to plan for further reservoir development and management strategies. This paper shares the geological and reservoir engineering integrated approaches to resolve the reservoir connectivity uncertainties between I35M and I35U, which could be applied in similar coastal fluvial/deltaic settings. The paper also highlights the importance of multidiscipline integration in resolving reservoirs uncertainties.
Jamaludin, Izzuddin (PETRONAS Carigali Sdn Bhd) | Basri, A Hakim (PETRONAS Carigali Sdn Bhd) | Mohd Nor, Saiful Azam (PETRONAS Carigali Sdn Bhd) | Arsanti, Dian (PETRONAS Carigali Sdn Bhd) | Dzulkifli, Izyan Nadirah (PETRONAS Carigali Sdn Bhd) | Mohd Azkah, Mohd Zubair (PETRONAS Carigali Sdn Bhd)
Field A is located offshore of Peninsular Malaysia, consists of multi stacked reservoirs where previously the vertical communication between different units was considered to be well understood. Separate reservoir models were built independently where fair to good history matching were achieved during the dynamic modelling study. Subsequently two drilling campaigns were executed based on the simulation results. On top of that, regular reservoir surveillance and frequent simulation model updates have assisted in assessing vertical connectivity.
North of Field A, a recent drilling campaign in early 2019 indicated possible communication between infill wells in Unit 35U and water injectors in Unit 35L. One of the well is experiencing severe watercut production than initially forecasted. It is well understood that the seismic amplitude for Unit 35L is being overlapped by the stronger response of Unit 35U in the northern area. Due to that, the reservoir modelling and understanding for Unit 35L in this region is mainly driven by actual well controls and the geological model, rather than from seismic.
Meanwhile in the Southern area, a stable reservoir pressure trend is observed in Unit 27 despite reduction of cumulative voidage replacement ratio (VRR) from 0.6 to 0.4. Additionally well C02ST1 was producing oil at an increasing rate, a trend which the current reservoir model failed to match. The model also failed to explain the unreasonably high recovery factor (RF) of 50% for Unit 27 given the delayed water injection and small gas cap support.
Back to the North, well interference testing was conducted by shutting in water injectors in Unit 35L and observing the pressure response of a new well in Unit 35U using a permanent downhole gauge (PDG). Observations indicated a decrease in pressure response once injection was turned off, confirming the communication between the two units. Moving forward, two injectors for Unit 35L will be temporarily suspended to relax the watercut trend in the new wells, thus improving the oil rate.
In the South, a material balance study and reservoir 3D model suggest additional volume needs to be introduced for Unit 27, which indicates that it is probably draining Unit 35U oil due to a higher level of vertical communication and overlapping sand bodies between both units. This is also supported by produced water salinity readings of well C02ST1 (Unit 27) having similar values as Unit 35U wells rather than other Unit 27 wells.
Communication between different layers often requires longer time and a significant amount of production to be well established and observed. This case study proves that reservoir understanding can still be a mystery even when the field is reaching 20 years of production.
Tan, Yvonne (Repsol Oil & Gas Malaysia Ltd.) | Ser, Kong Aik (Repsol Oil & Gas Malaysia Ltd.) | Rahman, Rasheed (Repsol Oil & Gas Malaysia Ltd.) | Foo, Say Jeow (Repsol Oil & Gas Malaysia Ltd.) | Lim, Kok Wei (Repsol Oil & Gas Malaysia Ltd.)
Abstract This paper showcases the tailored initiatives undertaken in a different economic climate in view of low oil price in maturing and capturing potential development opportunities for a large-sized, brownfield asset. The subject field is mature, having over 250 wells with over 20 years of production history and approaching its end of economic life. The study emphasized pursuit of a fast and cost-effective approach in identification of several potential behind-casing recompletion opportunities in addition to multiple infill drilling opportunities. From well log observation to seismic interpretation, and from material balance to simulation modeling, the approaches utilized were tailored based on the level of reservoir complexities. Lower cost, lower risk, behind pipe opportunities had previously not been a focus or thoroughly assessed since the company had focused on infill drilling opportunities. A robust execution plan, minimizing rig moves, was also prepared to synergize the ongoing and planned infill drilling campaigns in the field. An infill drilling well proposal was approved as part of the 2014 Field Development Plan (FDP) update with regulators. This plan was subsequently deferred due to drop in oil price resulting lower economics. However, with the field approaching the end of its economic producing life, a revisit of potential opportunities was conducted by a multi-disciplinary team. Results of the more recent opportunities identification and successful drilling campaigns have revived the proposal for the infill well given the synergies with rig utilization. The team went through a simplified governance process on the FDP, revisiting the simulation model and proposed to drill a horizontal infill production well instead of dual-string deviated well (originally envisioned for long string as an infill producer in the target reservoir and short string completed as a water injector in a different reservoir). Due to further well performance analysis, injection support on the other reservoir was no longer deemed necessary. The team analysis for arriving at this optimization as well as the behind-casing recompletion opportunities will be shared in this paper. This is a case study on how assimilated and innovative approaches undertaken in a different economic climate can be crucial to accelerate a brownfield re-development to extend the economic life of a mature producing field. A multi-disciplinary team applied creative thinking and cooperative efforts to a mature field to revive economic viability. Revisiting previously identified opportunities in the context of a low oil price environment and a simplified regulatory governance process, cross functional and cooperative technical and financial team work were important in facilitating timely decisions needed to move forward. A similar approach will be undertaken for future work in other fields.
Yin, K. Yin (PETRONAS Carigali Sdn Bhd) | Masoudi, R. (PETRONAS) | Rajput, S. (Gaffney-Cline and Associates) | Kandau, Flavia (Baker Hughes) | Amat, Hadi B. (PETRONAS) | Ring, M. (Baker Hughes) | Bertoldi, Luca (Baker Hughes) | Ismail, S. (PETRONAS Carigali Sdn Bhd)
Abstract The success of extracting the best value from mature heterogeneous fields to meet global energy challenges is directly linked to innovation and creativity. The development of these fields requires optimized economic models and fit for purpose reservoir depletion strategies. Petroleum geoengineering is the answer to evaluating remaining opportunities and managing the key uncertainties using smart technologies and reducing the risk of development. This paper describes the field example of how a petroleum geoengineering based approach can optimize the fast track development of a marginal fault block within a complex oil field which is located in offshore Sarawak Malaysia. The advantages of this workflow compared to the conventional field development plan (FDP) approach is that the iterative time consumed in matching the dynamic model and adjusting the geological model has been properly managed. In our case study, this workflow has improved the quality of the technical proposal as well as saving project duration significantly. In accordance to the workflow, the reservoir architecture was interpreted based on seismic interpretation, geological and reservoir performance understanding. Seismic Inversion derived geobodies were then identified as development targets. Better delineation of the main geological features was achieved using a seismic inversion based algorithm. By prioritizing data consistency among geoscientists, geomodellers and reservoir engineers, a fast track field development plan was developed within manageable uncertainties. Greater reliability of inversion results help to avoid perpetuating bias tendencies on data used for model calibration or quality check. The petroleum geoengineering based study for such oil reservoir shows how an integrated approach enabled time saving for subsurface development concept identification covering range of estimated hydrocarbon volumes. As a result of geoengineering approach in marginal fault block, the technical proposal was completed within 8 months duration.