Success story of integrated subsurface study to deliver a successful infill drilling: Buntal-5 case study

Mapping Intimacies ◽

10.29118/ipa21-e-132 ◽

2021 ◽

Author(s):

B. Khoironi

Keyword(s):

History Matching ◽

Gas Field ◽

Water Contact ◽

Seismic Amplitude ◽

Water Breakthrough ◽

Geological Features ◽

Open Hole ◽

Geophysical Study ◽

Infill Drilling ◽

Geological Concept

Buntal is a mature gas field located in South Natuna Sea Block B PSC. The field was discovered by well Buntal-1 and delineated by appraisal well Buntal-2. The field consists of multi-stacked sandstone reservoirs, which were deposited under fluvial deltaic environment. The major Buntal reservoirs have been produced since 2004 from two subsea wells. Buntal-3 was producing from zones Beta-1 and Beta-2, while Buntal-4 was a horizontal well producing from Zone-1C. Both of those wells had loaded up prior to Buntal-5 drilling. This paper describes the details of a multidisciplinary approach taken for the proposal of Buntal-5 infill drilling. An integrated geological and geophysical study were carried out to quantify resources and uncertainties of the remaining thin unproduced zones. In total, there are 8 virgin zones as Buntal-5 initial target namely Beta-0, Zone-1A, Zone-1B, Zone-1D, Zone-1E, Zone-2B, Zone-3 and Zone-3A. Max-trough seismic amplitude was utilized to identify geological features across for each Buntal reservoir. The result was then combined with geological concept based on its depositional environment to justify a reasonably higher hydrocarbon volume which can not be estimated only by wells’ data. A reservoir simulation study was also carried out to not only to evaluate production potential from the virgin zones but also to capture upside potential from the produced zones. Simulation history matching result on Zone-1C revealed early water breakthrough experienced by Buntal-4 well due to water cresting phenomena which left significant gas reserves. This result added upside potential to Buntal-5 which initially only targeted marginal remaining unproduced zones. The well was drilled at the end of 2019 and proven to be a major success. Buntal-5 open hole logs data indicate thicker and better virgin zones reservoir quality as expected by integrated geological and geophysical study. Furthermore, significant remaining gas was encountered in Zone-1C with actual gas water contact was within the simulation result proving the water cresting theory, the zone itself add well’s gas-in-place by 30% on top of the unproduced zones’ gas-in-place.

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Pluto 4D—Australia's first 4D over a gas field is an outstanding success

The APPEA Journal ◽

10.1071/aj17096 ◽

2018 ◽

Vol 58 (1) ◽

pp. 395 ◽

Cited By ~ 1

Author(s):

Larry Tilbury ◽

Andre Gerhardt

Keyword(s):

History Matching ◽

Feasibility Studies ◽

Seismic Survey ◽

Gas Field ◽

Water Contact ◽

Depth Migration ◽

Water Ingress ◽

Noise Data ◽

Excellent Control ◽

4D Seismic

The Pluto 4D seismic survey is Australia’s first 4D survey acquired over a gas field and has been an outstanding success despite the prior high technical risk of not being able to detect 4D differences above the background noise. At the time of the Pluto 4D monitor survey, the Pluto field had been on production for three years and nine months and produced approximately 1 Tcf of gas. The first monitor survey was acquired by PGS between November 2015 and February 2016 using dual sources and 12 streamers of 7050 m (geostreamer configuration). Also of note was the use of steerable sources to assist with repeatability, and towing the streamers at 20 m to minimise noise. Data was processed by CGG to pre-stack depth migration (PreSDM), took 12 months to deliver and required significant interaction between Woodside geoscientists and CGG to ensure an excellent 4D product. 4D feasibility studies carried out before acquisition showed that saturation changes (related to water ingress) were expected to show strong 4D responses near the gas water contact (GWC) and would be interpretable if the monitor survey was run after approximately three to four years of production. If the monitor survey was delayed, it showed that the pressure response became too large, swamped the 4D differences and made interpretation difficult or impossible. Strong ‘hardening’ responses on the 4D difference volumes are interpreted as water ingress into the field. Hardening responses are seen in all reservoir sequences in the Triassic from the TR27 to the TR32 units and range from strong (obvious) to weak (possible). Several examples are shown – the strongest response is seen in the large Triassic (TR27.3) valley within an essentially shale prone unit, which shows water ingress into the valley and moving upwards from the GWC towards the producing well. The results/insights from the 4D data have provided excellent control points for the history matching of the Pluto Field.

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The West Erregulla gas discovery. Implications for an extensive Permian play fairway across the onshore northern Perth Basin, Western Australia

The APPEA Journal ◽

10.1071/aj20034 ◽

2021 ◽

Vol 61 (2) ◽

pp. 594

Author(s):

A. Cortis ◽

A. Farley ◽

D. Lewis ◽

S. Cheong ◽

A. Chia ◽

...

Keyword(s):

Column Height ◽

The West ◽

Gas Field ◽

Water Contact ◽

Seismic Amplitude ◽

Axial Part ◽

Wireline Logs ◽

Large Gas Field ◽

Deep Fields ◽

New Discovery

The West Erregulla field is a significant new discovery in the northern Perth Basin that expands the play fairways for the basal Triassic/late Permian sandstones of the Dongara/Wagina formations and early Permian sandstones of the Kingia/High Cliff formations. The 2019 discovery well, West Erregulla-2, targeted three stacked seismic amplitude anomalies interpreted to be gas-charged conventional sandstones at depths between 4100m and 5000m. Gas charge is confirmed in all three units. Gas is hosted in linked, reactivated Permian-aged fault blocks located in the axial part of the Dandaragan Trough. They represent a down-dip analogue to the Waitsia gas field NW of West Erregulla. Only the Kingia sandstone was tested in West Erregulla-2. It contains good to excellent quality reservoir with >55m of pay averaging 12.6% porosity and gas saturations of 65%. Despite deep burial, porosity of the reservoirs was retained by a combination of syndepositional clay coatings and early burial gas charge. Testing of this zone achieved a maximum sustained flow rate of 69mmcf/day. Wireline logs and seismic mapping suggest the presence of a large gas field with gross gas column height of >200m over an area of ~40km2. Scoping volumetric estimates using a range of possible gas water contact (GWC) suggest a P50 in-place original gas in place (OGIP) of ~1182 Bcf for the Kingia formation (informal name). The West Erregulla, Waitsia and Beharra springs deep fields contain significant gas resources. Their spatial distribution suggests the existence of a deep, regional Permian fairway that could cover a large portion of the Perth Basin.

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The method for modeling the development of a gas field on the basis of a hierarchy of mathematical models

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2019-5-3-69-82 ◽

2019 ◽

Vol 5 (3) ◽

pp. 69-82

Author(s):

Vitaly P. Kosyakov ◽

Amir A. Gubaidullin ◽

Dmitry Yu. Legostaev

Keyword(s):

Mathematical Models ◽

Energy State ◽

Reservoir Pressure ◽

Gas Field ◽

Water Contact ◽

Simple Models

This article presents an approach aimed at the sequential application of mathematical models of different complexity (simple to complex) for modeling the development of a gas field. The proposed methodology allows the use of simple models as regularizers for the more complex ones. The main purpose of the applied mathematical models is to describe the energy state of the reservoir — reservoir pressure. In this paper, we propose an algorithm for adapting the model, which allows constructing reservoir pressure maps for the gas field, as well as estimating the dynamics of reservoir pressure with a possible output for determining the position of the gas-water contact level.

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Reservoir Performance Prediction using Integrated Production Modelling (MBAL Software)

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d7627.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 1484-1489

Keyword(s):

Performance Prediction ◽

History Matching ◽

Material Balance ◽

Development Planning ◽

Reservoir Rock ◽

Rock Properties ◽

Production Operation ◽

Gas Field ◽

Reservoir Performance ◽

Fluid Properties

Reservoir performance prediction is important aspect of the oil & gas field development planning and reserves estimation which depicts the behavior of the reservoir in the future. Reservoir production success is dependent on precise illustration of reservoir rock properties, reservoir fluid properties, rock-fluid properties and reservoir flow performance. Petroleum engineers must have sound knowledge of the reservoir attributes, production operation optimization and more significant, to develop an analytical model that will adequately describe the physical processes which take place in the reservoir. Reservoir performance prediction based on material balance equation which is described by Several Authors such as Muskat, Craft and Hawkins, Tarner’s, Havlena & odeh, Tracy’s and Schilthuis. This paper compares estimation of reserve using dynamic simulation in MBAL software and predictive material balance method after history matching of both of this model. Results from this paper shows functionality of MBAL in terms of history matching and performance prediction. This paper objective is to set up the basic reservoir model, various models and algorithms for each technique are presented and validated with the case studies. Field data collected related to PVT analysis, Production and well data for quality check based on determining inconsistencies between data and physical reality with the help of correlations. Further this paper shows history matching to match original oil in place and aquifer size. In the end conclusion obtained from different plots between various parameters reflect the result in history match data, simulation result and Future performance of the reservoir system and observation of these results represent similar simulation and future prediction plots result.

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Application of the CL-systems technology for water injection wells at an oil and gas field

Istrazivanja i projektovanja za privredu ◽

10.5937/jaes0-31315 ◽

2021 ◽

Vol 19 (3) ◽

pp. 848-853

Author(s):

Liliya Saychenko ◽

Radharkrishnan Karantharath

Keyword(s):

Oil And Gas ◽

Water Injection ◽

Oil And Gas Industry ◽

Field Studies ◽

High Water ◽

Injection Wells ◽

Gas Field ◽

Water Breakthrough ◽

Oil And Gas Field ◽

High Water Cut

To date, the development of the oil and gas industry can be characterized by a decline in the efficiency of the development of hydrocarbon deposits. High water cut-off is often caused by water breaking through a highly permeable reservoir interval, which often leads to the shutdown of wells due to the unprofitability of their further operation. In this paper, the application of straightening the profile log technology for injection wells of the Muravlenkovsky oil and gas field is justified. In the course of this work, the results of field studies are systematized. The reasons for water breakthrough were determined, and the main ways of filtration of the injected water were identified using tracer surveys. The use of CL-systems technology based on polyacrylamide and chromium acetate is recommended. The forecast of the estimated additional oil produced was made.

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Infill Depleted Gas Well Cementing Challenges for Offshore Myanmar Drilling Operations

10.2118/201010-ms ◽

2021 ◽

Author(s):

Ajita Ang C K Ang ◽

Avinash A Kumar Kumar ◽

Syazwan B A Ghani Ghani ◽

Nann N N Maung Nann ◽

M Hanif Yusof Yusoff ◽

...

Keyword(s):

Water Production ◽

Cement Slurry ◽

Water Contact ◽

Gas Well ◽

Well Drilling ◽

Depletion Rate ◽

Open Hole ◽

Drilling Operations ◽

Sensitivity Studies ◽

Remedial Work

Abstract Infill well drilling was planned and executed to increase production in a significantly depleted field. A total of 3 infill wells were drilled in 2 different layers of reservoir for an offshore operator in Myanmar. In the offset wells, water production had become significantly higher throughout. Previously all offset wells in this field were completed with open hole sand screens was chosen to isolate the water bearing sand in the sand reservoir below. Pore pressure prognosis were calculated from offset well depletion rate. Reservoir formation properties is assumed to be same throughout the field. The first well was drilled and was found that there were two gas water contacts through the 3 targeted sand layers. The gas water contact and WUT (Water Up To) in this well were unexpected and it was prognosed that these gas water contact are there due to compartmentalization. The 7" liner were set and cemented throughout these reservoirs. The cement job went as per the plan and there were no losses recorded during cementing. However, initial cement log did not show isolation. 2 more runs of cement log were performed 6 days and 10 days later while conducting intervention activities on other wells. All three cement log came to the same conclusion, showing no isolation throughout the annulus of the 7" production liner. Significant amount of gas had percolated into the annulus over time. Despite no evidence of poor cement slurry design observed during running various sensitivity studies and post-job lab tests final cement log, which was conducted under pressure and confirmed no hydraulic isolation. A cement remedial job was planned and an investigation was conducted to identify the plausible root causes. This paper explains on the root causes of poor cement presence in the annulus, and the remedial work that took place to rectify the issue.

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INSIM-FPT-3D: A Data-Driven Model for History Matching, Water-Breakthrough Prediction and Well-Connectivity Characterization in Three-Dimensional Reservoirs

10.2118/203931-ms ◽

2021 ◽

Author(s):

Hui Zhao ◽

Wei Liu ◽

Xiang Rao ◽

Guanglong Sheng ◽

Huazhou Andy Li ◽

...

Keyword(s):

Simulation Model ◽

History Matching ◽

3D Model ◽

Reference Model ◽

Three Dimensional ◽

Data Driven ◽

Series Data ◽

Reference Models ◽

Water Breakthrough

Abstract The data-driven interwell simulation model (INSIM) has been recognized as an effective tool for history matching and interwell-connectivity characterization of waterflooding reservoirs. INSIM-FT-3D (FT: front tracking) was recently developed to upgrade the applicationdimension of INSIM series data-driven models from two-dimensional (2D) to three-dimensional (3D). However, INSIM-FT-3D cannot accurately infer the dynamic change of well-connectivity and predict well's bottom-hole pressure (BHP). The main purpose of this study intends to expand the capability of INSIM-FT-3D to empower for the assimilation of BHPs, the reliable prediction of water breakthrough and the characterization of dynamic interwell-connectivities. The default setting of well index (WI) in INSIM-FT-3D based on Peaceman's equation does not yield accurate BHP estimates. We derive a WI that can honor the BHPs of a reference model composed of a set of 1D connections. When history matching BHPs of a 3D reservoir, we show that the derived WI is a better initial guess than that obtained from Peaceman's equation. We also develop a flow-path-tracking (FPT) algorithm to calculate the dynamic interwell properties (allocation factors and pore volumes (PVs)). Besides, we discuss the relationship between the INSIM-family methods and the traditional grid-based methods, which indicates that the INSIM-family methods can calculate the transmissibility of the connection between coarse-scale cells in a more accurate manner. As an improvement of INSIM-FT-3D, the newly proposed data-driven model is denoted as INSIM-FPT-3D. To verify the correctness of the derived WI, we present a 1D problem and a T-shaped synthetic reservoir simulation model as the reference models. BHPs and oil production rates are obtained as the observed data by running these two reference models with total injection/production-rate controls. An INSIM-FPT-3D model is created by specifying the transmissibilities and PVs that are the same as those in the reference model. By applying the derived WIs in INSIM-FPT-3D, the resulting BHPs and oil rates obtained agree well with the reference model without further model calibration. Applying INSIM-FPT-3D to a synthetic multi-layered reservoir shows that we obtain a reasonable match of both BHPs and oil rates with INSIM-FPT-3D. Compared with the FrontSim model, the INSIM-FPT-3D model after history matching is shown to match the dynamic PVs from FrontSim reasonably well and can correctly predict the timing of water breakthrough. By allowing for the assimilation of BHP data, we enable INSIM-FPT-3D to history match a green field with limited production history and forecast the timing of water breakthrough. The improved INSIM-FPT-3D leads to more accurate characterization of the interwell connectivities.

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Significant Performance Improvement with MPD in HPHT Narrow Drilling Window Campaign in the North Sea

10.4043/31217-ms ◽

2021 ◽

Author(s):

Babar Kamal ◽

Abdul Saboor ◽

Graeme MacFarlane ◽

Frank Kernche

Keyword(s):

Precise Determination ◽

Lessons Learned ◽

Overburden Pressure ◽

The North ◽

Fracture Pressure ◽

Open Hole ◽

Infill Drilling ◽

Significant Performance ◽

And Performance ◽

Formation Pore Pressure

Abstract Significant depletion in reservoir pressure, huge uncertainties in pore and fracture pressure, high overburden pressure on top of reservoir, Narrow Mud Weight Window (NMWW) and Partial/Total losses whilst entering the reservoir made these HPHT (High Pressure High Temperature) wells conventionally un-drillable. Due to these substantial challenges these wells were considered not only costly but also carry a high probability of failure to reach well TD (Total Depth). MPD (Managed Pressure Drilling) is a safer and more effective drilling technique as compared to conventional drilling, especially in wells with NMWW and downhole hazards. The precise determination and dynamic downhole pressure management was imperative to complete these wells without well control incidents. The Constant Bottom Hole Pressure (CBHP) variant in combination of automated MPD system was deployed with a mud weight statically underbalanced while dynamically managed above formation pore pressure to minimize the overbalance across the open hole. MPD enabled the operator to efficiently navigate Equivalent Circulation Density (ECD) through the pore and fracture pressure window, allowed significant improvements throughout the entire campaign. This paper discusses the challenges faced during the last three wells drilled in the campaign which includes equipment issues, commissioning delays, losses whilst drilling, Managed Pressure Cementing (MPC), 7" drill-in-liner and plugged/blocked lines due to weather and mud conditions. The paper describes HPHT infill drilling experience, specific techniques, practices as well as lessons learned from each well during the campaign were implemented to address challenges and to improve performance. The MPD system commissioning was optimized by repositioning the lines which saved significant critical rig time. The blowdown points were added on the lines that were not operational continuously therefore a procedure was developed for flushing to avoid plugging. Optimized drilling strategy was also developed where MW was further reduced to avoid losses as observed in previous wells and CBHP was maintained by manipulating Surface Back Pressure (SBP) from surface. This paper also discusses continuous improvements /upgrades in MPD operating software which assisted the operator in accurate monitoring of flow, SBP and BH-ECD to save significant rig cost in terms of invisible Non-Productive Time (NPT). MPD is a drilling enabler and performance enhancer which saved 80 days of Authorization for Expenditure (AFE) on this challenging HPHT campaign.

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