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.
An Under Balanced Drilling (UBD) pilot project in the Heera and Mumbai High fields of Western offshore India was recently completed successfully. The objective of the project was to establish whether the technology can improve productivity performance in the reservoir section, avoid reservoir damage and thereby enhance oil production from the wells. This paper incorporates the drilling experiences and challenges faced during execution of this pilot project, the well design considerations and methodology, evaluation of the drilling fluid systems and also describes the tangible benefits of using this technology in the drilling of these sections and wells. In terms of the productivity gains from drilling these wells using UBD technology, through the sub-hydrostatic formations offshore Mumbai, the results were very positive. With the success and encouraging results from the pilot project, more wells are now planned, including wells in the losses-prone and depleted Mumbai High and Neelam fields, to incorporate the experiences of the learning curve.
Agrawal, Gaurav (Schlumberger) | Kumar, Ajit (Schlumberger) | Mishra, Siddharth (Schlumberger) | Dutta, Shaktim (Schlumberger) | Khambra, Isha (Schlumberger) | Chaudhary, Sunil (ONGC) | Sarma, K. V. (ONGC) | Murthy, M. S. (ONGC)
Objectives/Scope: XYZ is one of the marginal fields of Mumbai Offshore Basin located in western continental shelf of India. Wells in this field were put on ESP for increasing the production. Regular production profiling with traditional production logging was done in these wells to ascertain the water producing zones if any and do the subsequent well intervention if required.
Methods, Procedures, Process: In few deviated wells with low reservoir pressure, low flow rates and large casing size, massive recirculation was observed due to which spinner readings were highly affected. In such scenarios, quantitative interpretation with conventional production logging is highly difficult. Only qualitative interpretation based on temperature and holdup measurements can be made which might not completely fulfill the objective. In one of the deviated wells, massive recirculation was observed due to large casing size. Recirculation on ESP wells is generally not expected due to high energy pressure drawdown exerted on the well. Traditional production logging imposed difficulty in interpretation due to recirculation. Only qualitative interpretation was made from temperature and holdup measurements. Hence advanced production logging tool called Flow Scan Imager (FSI*) with 5 minispinners, 6 sets of electrical and optical probes, designed for highly deviated and horizontal wells to delineate flow affected due to well trajectory, was suggested for quantitative interpretation in such wells suffering with recirculation.
Results, Observations, Conclusions: In the next well, production profiling was to be done before ESP installation in similar completion as the last well. Therefore, huge recirculation phenomenon was expected in the well. FSI was proposed in this deviated well with recirculation for production profiling and also for finding out the complex flow regime inside the wellbore. FSI helped in proper visualization of the downhole flow regime with the help of multispinners and probes. Quantitative interpretation was made with the help of FSI data. Also, quantification was confirmed inside the tubing (lesser cross section area) where no recirculation is expected as the mini spinner does not collapse inside the wellbore. In traditional production logging, it is generally not possible due to the collapsing of full bore spinners inside tubing. Better understanding of the flow regime can be obtained with FSI than conventional production logging due to the presence of multiple sensors. Later interventions using FSI results have shown significant oil gains.
Novel/Additive Information: FSI was used in deviated ESP wells with recirculation for production profiling, accurate quantification, better understanding of flow regimes and to take improved well intervention decisions.
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.
Nandi, Anindya (Schlumberger) | Sarkar, Subhadeep (Schlumberger) | Chatterjee, Chandreyi (Schlumberger) | Das, Sourav (Schlumberger) | Pattanaik, Sambit (Schlumberger) | Majumder, Chandan (Schlumberger) | Haldia, Bhopal Kumar (Oil & Natural Gas Corporation Ltd.) | Chaturvedi, Praveen Chandra (Oil & Natural Gas Corporation Ltd.) | Srivastava, Siddharth (Oil & Natural Gas Corporation Ltd.) | Verma, Malay (Oil & Natural Gas Corporation Ltd.) | Sarkar, Sutanu (Oil & Natural Gas Corporation Ltd.)
Owing to the depleting reserves in the conventional reservoirs over the last few years, unconventional reservoirs have gained significant importance in the exploration of oil and gas. Basement rocks, though non-sedimentary in origin, is looked upto as one of the important unconventional reservoirs. Deccan volcanics in Kutch-Saurashtra is one such example from India. This study shows and validates a methodology of how acoustic log data can be integrated with borehole images to understand reservoir properties that governs flow. It has been noticed that presence of open fractures is not the single biggest driver contributing to production. Insitu stress plays a critical role in guiding fracture mobility. To understand and determine which fractures would contribute to flow, a geomechanical study of performing the fracture stability analysis has been carried out. This generates a Mohr circle plot that defines the Mohr-Colomb shear failure criteria using the stress and critical fracture angles. Combining these three-way approaches of acoustic, image log and geomechanics, a workflow has been established for this field to identify fractures and quantify the permeable zones. This workflow has been used for two nearby wells in this field and subsequent result emphasises the utility of this method to find out sweet spots of fluid flow in fractured basement.
Ridha, Muhammad (Universitas Diponegoro) | Nurdiansyah, Mukhammad (Universitas Diponegoro) | Zamili, Jonathan Sofiawan (Universitas Diponegoro) | Triwigati, Purnaning Tuwuh (Universitas Diponegoro) | Muslih, Yan Bachtiar (Universitas Pertamina) | Farida, Widiastuti Nur (Pertamina Hulu Energi)
This study area is located on Dolok River, Banyumeneng, Western Kendeng Basin, which has a direct relation to the Sunda Shelf as the largest sediment supply for Kendeng Basin. The study aims to determine the changes of depositional succession on Late Neogene in the Western Part of Kendeng Basin and identify the diagenesis process and the implication to the physical properties of Calciclastic Submarine Fan (CSF) Deposits.
The methods used in this study are field observation which was used to gather the stratigraphic record of deposits and rock samples analysis through petrography, microfossil, diagenesis, porosity and permeability. Measured stratigraphic section was used to determine the depositional pattern, facies and processes. Petrography analysis was used to determine the composition and diagenetic features. Moreover, the microfossil analysis was used to determine the relative age and the bathymetry of deposits, while the porosity was calculated using the mass-weighted method and permeability was calculated using the permeameter gas method to determine the quality of deposits as the hydrocarbon reservoir.
Generally, the section shows the progradation sequence characterized by the Lobe Fringe deposits which gradationally change to the Outer Shelf deposits. The lower part was characterized by thick Hemipelagic Mudstone and Thin-bedded Calciturbidite Facies, showing the part of Lobe Fringe Deposits. The second part was divided into MTD type 1 and 2, MTD type 1 consist of Conglomeratic Calciturbidite, Clast-Supported Debrites, and Graded Calciturbidite, then the MTD type 2 is slumped levee deposits, showing the high-density turbidity current channel complexes on the Gullied Upper Slope. The third part was characterized by conglomeratic calciturbidite, graded calciturbidite, clast supported debrites, and hemipelagic mudstone, included into Braided Axis Channel facies. The fourth part was characterized by the interbedded of Thin-Bedded Calciturbidite, Laminated Calciturbidite and Hemipelagic Mudstone Facies, showing the Levee facies. The upper part was characterized by thick Cross-Bedded Calciclastic deposit, showing the Outer Shelf depositional environment. Furthermore, the Flute Cast shows the NW-SE paleocurrent direction which indicates that the Sunda Shelf Paleo-Environment was considered as the major sediment supply for this area. Moreover, the Foraminifera analysis shows the Lower Bathyal - Middle Neritic bathymetry on Middle - Late Miocene (N9 N18). The porosity and permeability quality ranged from 2.13 - 6.38% and 7.54 - 86.38 mD. Combined with petrography analysis, it can be analyzed that the diagenesis processes of Banyumeneng CSF deposits are micritization or grain-coating clays, compaction, cementation, neomorphism, and dissolution. The poorly-sorted materials and highly-cementation process may restrict the pore-throat and reduce the permeability as well. As the outcrop exposed, the meteoric water acts to dissolve the cement, leaving the small porosity inside. Therefore, the pores tend to be the secondary pores which are formed by the post depositional dissolution.
Significant challenges meeting together make Keshen gas field in Kucha foreland basin become unique from geosciences, engineering and economics points of view. These challenges generally link to harsh geography, super deep (>6500m TVD), thick conglomerates (up to 3000m), heterogeneous salt-gypsum laminations (up to 2000m), complex thrust-nappe structure, HTHP, and ultra-tight (matrix permeability < 0.1 md). This paper gives a comprehensive review how the geoengineering Long March assists to successfully develop this field.
A geoengineering team was established to persistently attack on this world-class championship with high-level planning since 2012. Specific research and development of engineering technologies and solutions for data acquisition, drilling, completion, stimulation, testing and production and studies were taking place in parallel. To ensure seamless integration from geosciences and engineering to operation, a five-year geoengineering study was proactively and progressively executed which includes four major steps with respective objectives including 1) understanding fluid distribution and producibility, 2) well production breakthrough and enhancement, 3) optimization of well stimulation and economics, and 4) optimization of field management including surprising sanding problem.
It was recognized three elements and their interactions are critical for production enhancement which are natural fracture (NF) characteristics, production controlling mechanism, and stimulation optimization under super deep, HPHT and extremely high stress conditions. The bottleneck for study was poor seismic quality due to super depth, pre-salt, and complex thrust-nappe structures. Hence the team established comprehensive methodologies with iterative improvements to overcome this bottleneck. Using regional structural geology, outcrops, cores, images and logs as inputs, structure restoration and geomechanics simulators were combined to perform structure restoration, paleo-stresses, and in-situ stresses and eventually 3D NF prediction. To understand production mechanism, analysis of geological and geomechanical factors, NF and stress relationships, single parameter and multiple variables, and transient and production performance were integrated. Big core studies were conducted to understand fracability, NF and hydraulic fracture (HF) interactions, and selections of HF fluids. Based upon, a stimulation optimization approach was implemented which included engineered completion designs, HF modeling and parametric studies, post-frac analysis and optimization, and time effects through high-resolution coupled geomechanics and reservoir simulation. All efforts with evolving knowledge were eventually developed as an interactive expert system to guide systematic stimulation optimization, sanding management and development optimization.
With increasing understanding of reservoir, and implementing innovative solutions, it was enabled to drill wells at optimal locations with less time, simplified well configuration, and less constraints on stimulation and production operations. By 2017, well construction time was reduced by half, natural productivity of wells was doubled, productivity after stimulation was tripled, and overall cost of wells was largely reduced. The success achieved would boost confidence and lighten on development of other challenging fields.
In early 2016, oil price has fallen to its lowest level (30.32 US$/bbl) over the last 12 years. Since then, petroleum exploration and exploitation activities are decreasing worldwide due to high production cost and low oil prices. As of December 2017, there were 435 projects approved by the government of Indonesia, which is expected to maintain the national energy supply and to increase national income from oil and gas industry. This paper will evaluate and analyze the oil and gas reserves per project to help Contractors to find the area in Indonesia that has the highest trend of oil and gas reserves per project so that they can produce big revenue. The purpose of this paper is, to divide the geographical areas of Indonesia into 5 different areas (Sumatera, Java, Kalimantan, Sulawesi and Papua). Then, to collect the data that related to projects and oil and gas discoveries and the trend of oil and gas discoveries per project are calculated and analyzed by using the creaming curve method, the result will be distributed to those aforementioned areas and finally define the area that has the highest and the lowest number (trend) of oil and gas discoveries per project. Based on the analysis of 435 Projects in Indonesia, Sulawesi is estimated to have the highest amount of oil and gas reserves by 111.24 MMBOE per project which means that these areas become the most interesting area for Contractors to produce profitable projects, meanwhile Sumatera is estimated to have the lowest amount of oil and gas reserves by 7.19 MMBOE per project which means that these areas are becoming the most mature area in Indonesia. Finally, this paper is expected to provide contractors a quick look at oil and gas industry in Indonesia especially the contractors who are looking for the giant oil and gas reserves and also help them create their petroleum exploration and exploitation strategy in Indonesia by considering on this information which will provide benefits for both government and contractor.