Succesful Application of Cluster Drilling Concept to Reduce Cost and Increase Profitability in a Mature Onshore Gas Field in East Kalimantan, Indonesia

Author(s):  
Hazman Chatib ◽  
Harry Alam ◽  
Andre Wijanarko ◽  
Umi Kurniyati ◽  
Yoseph Agung ◽  
...  
Keyword(s):  
1996 ◽  
Vol 61 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Yoshiyuki Hayashi ◽  
Tsuyoshi Inage ◽  
Ikuo Suzuki ◽  
Hiroshi Nagura

2021 ◽  
Author(s):  
R. Herbet

Tunu is a giant gas field located in the present-day Mahakam Delta, East Kalimantan, Indonesia. Tunu gas produced from Tunu Main Zone (TMZ), between 2500-4500 m TVDSS and Tunu Shallow Zone (TSZ) located on depth 600 - 1500 m TVDSS. Gas reservoirs are scattered along the Tunu Field and corresponds with fluio-deltaic series. Main lithologies are shale, sand, and coal layers. Shallow gas trapping system is a combination of stratigraphic features, and geological structures. The TSZ development relies heavily on the use seismic to assess and identify gas sand reservoirs as drilling targets. The main challenge for conventional use of seismic is differentiating the gas sands from the coal layers. Gas sands are identified by an established seismic workflow that comprises of four different analysis on pre-stack and angle stacks, CDP gathers, amplitude versus angle(AVA), and inversion/litho-seismic cube. This workflow has a high success rate in identifying gas, but requires a lot of time to assess the prospect. The challenge is to assess more than 20,000 shallow objects in TSZ, it is important to have a faster and more efficient workflow to speed up the development phase. The aim of this study is to evaluate the robustness of machine learning to quantify seismic objects/geobodies to be gas reservoirs. We tested various machine learning methods to fit learn geological Tunu characteristic to the seismic data. The training result shows that a gas sand geobody can be predicted using combination of AVA gather, sub-stacks and seismic attributes with model precision of 80%. Two blind wells tests showed precision more than 95% while other final set tests are under evaluated. Detectability here is the ability of machine learning to predicted the actual gas reservoir as compared to the number of gas reservoirs found in that particular wells test. Outcome from this study is expected to accelerate gas assessment workflow in the near future using the machine learning probability cube, with more optimized and quantitative workflow by showing its predictive value in each anomaly.


Author(s):  
A.T. Santoso

The Tunu field is a swamp giant gas field located in the Mahakam Delta, East Kalimantan. Stratigraphically, this field has an anticline structure with three main intervals; Tunu Shallow Zone (TSZ), Fresh Water Zone (FWZ), and Tunu Main Zone (TMZ). Shallow gas reservoirs of TSZ have been produced since 2008, following the production of TMZ in the 1990s. Drilling targets in the shallow gas reservoir decreased significantly due to limited reservoir targets, high inclination wells and a low oil price environment. The utilization of radioactive source logging (density and neutron) on Logging While Drilling (LWD) tools is not recommended to be performed in open hole mode for operational and safety issues (e.g: tool stuck). Thus, LWD Monopole sonic is chosen as a replacement of LWD Neutron-Density logs and helps to differentiate between shallow gas potential and coal lithology which is the main challenge in TSZ at interval depth above 1200 mSS. The methodology utilized sonic semblance (STRA) and compressional slowness (DTc) data at real-time and memory data logs, so early decision can be made in drilling mode. In a gas-bearing reservoir, both semblance and slowness are missing, while in coal it produced strong semblance. In order to differentiate carbonate lithology, additional data, such as cutting, calcimetry, drilling Rate of Penetration and Gas While Drilling are utilized. During 2018-2020, 5 wells have been drilled using LWD Monopole sonic together with LWD GR-Resistivity-Neutron-Density (Triple Combo) to calibrate the fluid interpretation and 3 trial wells with only GR-Resistivity-Monopole Sonic. As a result, LWD Monopole sonic is able to differentiate between Gas and Coal based on semblance and slowness with a success ratio up to 80%. This LWD Monopole Sonic provides a non-radioactive solution for safe and effective logs acquisition for shallow gas identification that could be applied in oil and gas fields outside Mahakam.


2016 ◽  
Vol 10 (3) ◽  
pp. 117
Author(s):  
Priatin Hadi Widjaja ◽  
D. Noeradi ◽  
A.K. Permadi ◽  
Ediar Usman ◽  
Andrian Widjaja

Kajian geologi migas di Cekungan Tarakan relatif sangat kurang dibandingkan dengan Cekungan Kutai, diantaranya mengenai analisis stratigrafi sekuen yang lebih detil dan komprehensif, tingkat variasi lapisan sedimen di daerah transisi dengan laut dangkal sampai sedang dan keterkaitan dengan penentuan potensi migas. Padahal eksplorasi minyak dan gas bumi di Cekungan Tarakan, Kalimantan Timur telah mengalami proses waktu yang sangat panjang bahkan termasuk salah satu eksplorasi tertua di Indonesia. Namun eksplorasi di wilayah lepas pantai termasuk di timur Pulau Tarakan masih belum ditemukan lapangan migas yang bernilai ekonomis. Ini sangat berbeda dengan hasil eksplorasi Cekungan Kutai di lepas pantai dan laut-dalam yang telah mengalami kemajuan signifikan dalam 10 tahun terakhir setelah ditemukan beberapa lapangan migas laut-dalam seperti West Seno dan Gendalo. Berdasarkan pada pemerolehan data yang terdiri dari penampang seismik 2D, log sumur, rangkuman data biostratigrafi dan data check-shot, kajian dilakukan secara bertahap mulai dari analisis sekuen dan korelasi log sumur, interpretasi dan analisis seismik stratigrafi, pemetaan bawah permukaan, dan penentuan lokasi yang berpotensi migas. Tahapan metodologi kajian ini menggunakan beberapa perangkat lunak yang diproses secara integratif. Hasil akhir kajian dari integrasi peta struktur kedalaman dan peta isopach serta dukungan data petrofisik dari aspek kualitas batuan reservoir diperoleh dua lokasi yang berpotensi migas: Potensi Migas-1 di bagian tenggara dekat Pulau Tarakan merupakan jebakan struktur antiklin yang dikontrol sesar-sesar inversi dan Potensi Migas-2 di lepas pantai bagian timur wilayah kajian berupa jebakan struktur hidrokarbon sebagai sebuah antiklin yang memanjang relatif arah SEE – NWW. Kata kunci: Tarakan, sekuen, seismik, potensi migas Study of Petroleum geology in the Tarakan Basin is relatively less than in the Kutai Basin such as detailed and comprehensively sequence stratigraphy, variation of sediment layering from transition to outer-neritic zone and its related to determination of oil and gas potential locations. Oil and gas exploration in Tarakan Basin, East Kalimantan, has been carried out for the last a hundred years ago and its include as the oldest basin in Indonesia. Unfortunately, oil and gas field in eastern part of offshore Tarakan Island has not yet been discovered significantly. In contrast, offshore and deep-water oil and gas fields of Kutai Basin has been discovered significantly i.e. West Seno and Gendalo Fields. Based on data of 2D seismic in SEGY-files, well log in LAS-file, biostratigraphy and check-shot data, then steps of research followed by a sequence analysis, wells correlation, interpretation and analysis of seismic stratigraphy, subsurface mapping and determination of oil and gas potential locations. The results of this study are oil and gas potency 1 and potency 2. Potency 1 is located in south-eastern part of Tarakan Island where anticlinal traps are controlled by inversion faults. In contrast, potency 2 is an anticlinal trap located in offshore at the eastern part of the study area. Key words: Tarakan, sequence, seismic, oil and gas potential


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