Lingkungan Pengendapan dan Analisis Ukuran Butir untuk Penentuan Resiko Sanding-plugging Issues dan Interval Perforasi di Zona 'Uta', Lapangan 'BK, HD, dan PC', Blok Mahakam, Cekungan Kutai, Kalimantan Timur

MUTAWIF ILMI M, Ir. Jarot Setyowiyoto, M.Sc., Ph.D., IPU., ASEAN Eng.

2021 | Skripsi | S1 TEKNIK GEOLOGI

Cekungan Kutai merupakan salah satu cekungan di Indonesia yang menghasilkan hidrokarbon dalam jumlah besar. Blok Mahakam merupakan salah satu blok penghasil hidrokarbon utama di Cekungan Kutai. Blok Mahakam dikelola oleh PT. Pertamina Hulu Mahakam (PHM). Produksi utama yang dilakukan oleh PHM saat ini berfokus pada zona dangkal yang disebut sebagai Zona �¢ï¿½ï¿½Uta�¢ï¿½ï¿½ dengan burial 1250mSS-1750mSS. Zona �¢ï¿½ï¿½Uta�¢ï¿½ï¿½ umumnya memiliki tingkat konsolidasi batuan yang rendah yang sering menyebabkan sanding-plugging issues. Issues tersebut menyebabkan penurunan produksi hidrokarbon secara signifikan. Issues tersebut juga membuat PHM harus memperhitungkan penentuan interval perforasi yang optimal untuk mengurangi terjadinya sanding-plugging issues. Permasalahan utama adalah PHM belum pernah melakukan studi mengenasi tekstur ukuran butir batuan setiap lingkungan pengendapan yang berkembang untuk mengatasi issues tersebut. Salah satu fokus utama adalah pada Lapangan �¢ï¿½ï¿½BK, HD, dan PC�¢ï¿½ï¿½ dengan reservoir produksi utama di Zona �¢ï¿½ï¿½Uta�¢ï¿½ï¿½. Issues tersebut dapat dianalisis lebih lanjut dengan melakukan analisis ukuran butir setiap lingkungan pengendapan pada sumur-sumur yang memiliki data core. Sumur-sumur tersebut akan menjadi analog sumur-sumur uncored di Blok Mahakam. Sementara itu, penentuan resiko sanding-plugging issues dan interval perforasi dilakukan pada sumur-sumur uncored. Berdasarkan deskripsi core, elektrofasies, dan korelasi; lingkungan pengendapan yang berkembang adalah fluvial channel (CF7), fluvial-influenced distributary channel (CF6a), tidal-influenced distributary channel (CF6b), distributary mouth bar (CF5), distal delta front bar (CF4), overbank deposit (CF2), dan prodelta (CF1). Berdasarkan rasio sand:fine particle, tesktur ukuran butir khas dari hasil LPSA adalah CF7 = 90:10, CF6a = 88:12, CF6b = 70:30, CF4 = 60:40, dan CF1 = 10:90, sementara dari hasil Sieve adalah CF7 = 94:6, CF5 = 75:25, dan CF4 = 80:20. Berdasarkan rasio sand:fine particle setiap lingkungan pengendapan (LPSA), lingkungan pengendapan yang memiliki resiko tinggi adalah CF1 dan CF4, resiko menengah adalah CF6b, resiko rendah adalah CF6a dan CF7. Sementara itu, CF5 memiliki resiko menengah (Sieve). Kemudian, resiko sanding-plugging issues pada beberapa sumur uncored yang telah dianalisis memiliki tingkat yang bervariasi, Sumur BK-7 resiko tinggi, BK-1 resiko rendah, dan BK-12 resiko sedang. Sementara itu, interval perforasi optimal Sumur BK-18 terletak pada interval burial 1616mSS �¢ï¿½ï¿½ 1621,5mSS. Bedasarkan penelitian ini dapat diketahui, studi tekstur ukuran butir batuan setiap lingkungan pengendapan dapat digunakan untuk mengatasi masalah sanding-plugging issues dan penentuan interval perforasi yang optimal.

Kutai Basin is one of the basins in Indonesia that produces large amounts of hydrocarbons. Mahakam Block is one of the main hydrocarbon producing blocks in the Kutai Basin. Mahakam block is managed by PT. Pertamina Hulu Mahakam (PHM). The main production carried out by PHM currently focuses on a shallow zone called the 'Uta' Zone with a burial of 1250mSS-1750mSS. The 'Uta' zone generally has a low level of rock consolidation which often causes sanding-plugging issues. These issues led to a significant reduction in hydrocarbon production. These issues also make PHM have to take into account the determination of the optimal perforation interval to reduce the occurrence of sanding-plugging issues. The main problem is that PHM has never conducted a study on the grain size texture of each developing depositional environment to address this issue. One of the main focuses is on the 'BK, HD, and PC' Fields with the main production reservoir in the 'Uta' Zone. These issues can be further analyzed by analyzing the grain size of each depositional environment in wells that have core data. These wells will be analogous to the uncored wells in the Mahakam Block. Meanwhile, the determination of the risk of sanding-plugging issues and the interval of perforation is carried out in uncored wells. Based on the descriptions of cores, electrofacies, and correlations; the depositional environment that developed was a fluvial channel (CF7), fluvial-influenced distributary channel (CF6a), tidal-influenced distributary channel (CF6b), distributary mouth bar (CF5), distal delta front bar ( CF4), overbank deposit (CF2), and prodelta (CF1). Based on the sand: fine particle ratio, the typical grain size of the LPSA results is CF7 = 90:10, CF6a = 88:12, CF6b = 70:30, CF4 = 60:40, and CF1 = 10:90, while from the Sieve result are CF7 = 94:6, CF5 = 75:25, and CF4 = 80:20. Based on the sand:fine particle ratio for each depositional environment (LPSA), the depositional environment that has a high risk is CF1 and CF4, the medium risk is CF6b, the low risk is CF6a and CF7. Meanwhile, CF5 has a medium risk (Sieve). Then, the risk of sanding-plugging issues in several uncored wells that have been analyzed has varying levels, Well BK-7 has high risk, Well BK-1 has low risk, and Well BK-12 has medium risk. Meanwhile, the optimal perforation interval of Well BK-18 lies in the burial interval 1616mSS - 1621.5mSS. Based on this research, it can be seen that the study of the rock grain size of each depositional environment can be used to solve the problem of sanding-plugging issues and determine the optimal perforation interval.

Kata Kunci : Lingkungan pengendapan, ukuran butir batuan, Zona Ã�¢ï¿½ï¿½UtaÃ