PARAMETER PETROFISIKA, KONTROL TIPE PORI TERHADAP POROSITAS, DAN PENENTUAN ZONA HIDROKARBON PADA INTERVAL KUJUNG-I, LAPANGAN ‘MUZZA’ CEKUNGAN JAWA TIMUR UTARA

Muhammad Fairuz Zain, Dr.Ing. Ir. Donatus Hendra Amijaya, S.T., M.T., IPM.

2026 | Skripsi | TEKNIK GEOLOGI

Cekungan Jawa Timur Utara merupakan salah satu cekungan penghasil hidrokarbon terbesar di Indonesia dengan cadangan minyak dan kondensat sebesar 53,7 million stock tank barrels serta cadangan gas dan asosiasi gas sebesar 480,1 BSCF. Penelitian ini dilakukan di Formasi Kujung-I yang memiliki litologi dominan berupa batugamping, sehingga memiliki heterogenitas yang cukup tinggi. Oleh karena itu, penting untuk dilakukan analisis penentuan zona reservoir dan zona hidrokarbon untuk mengetahui prospeknya dalam eksplorasi hidrokarbon. Analisis yang dilakukan adalah perhitungan parameter petrofisika, analisis kontrol tipe pori dan diagenesis terhadap nilai porositas, serta penentuan zona reservoir dan zona hidrokarbon. Metode penelitian meliputi pengondisian data, penentuan litologi dan analisis stratigrafi, korelasi stratigrafi, penentuan parameter input petrofisika, analisis petrofisika, analisis kontrol tipe pori terhadap porositas, dan analisis zona reservoir hidrokarbon. Hasil penelitian menunjukkan bahwa Interval Kujung-I terbagi menjadi dua unit litologi, yaitu Perselingan Batugamping dan Shale (LS-1) serta Batugamping sisipan Shale (LS-2). Korelasi stratigrafi menunjukkan penipisan LS-1 dan penebalan LS-2 ke arah timur laut. Analisis petrofisika menunjukkan bahwa nilai rata-rata Vsh LS-1 dan LS-2 pada litologi batugamping masing-masing sebesar 0,138 dan 0,100 v/v, PHIE sebesar 0,180 dan 0,145 v/v, serta Sw sebesar 0,584 dan 0,802 v/v. Analisis kontrol tipe pori terhadap porositas menunjukkan bahwa porositas tinggi berkaitan dengan leached porosity, moldic, dan proses pelarutan, sedangkan porositas rendah berkaitan dengan pori fracture, channel, pori tidak teridentifikasi, serta proses rekristalisasi. Penentuan zona reservoir dan hidrokarbon menunjukkan bahwa seluruh sumur memiliki interval reservoir dan net pay, dengan ketebalan net pay terbesar pada MZ-1 sebesar 349,48 ft dan terkecil pada MZ-5 sebesar 119,92 ft. Secara lateral, zona reservoir menebal ke arah timur laut seiring berkembangnya batugamping. Penyebaran zona hidrokarbon pada LS-2 cenderung terkonsentrasi di bagian atas pada sumur-sumur timur laut, namun merata di sumur barat daya, sedangkan pada LS-1 penyebarannya lebih merata di bagian timur laut dibandingkan bagian barat daya.

The North East Java Basin is one of the largest hydrocarbon-producing basins in Indonesia, with oil and condensate reserves of 53.7 million stock tank barrels and gas and associated gas reserves of 480.1 BSCF. This study was conducted in the Kujung-I Formation, which is predominantly composed of limestone, resulting in relatively high heterogeneity. Therefore, it is important to analyze the determination of reservoir zones and hydrocarbon zones to evaluate their prospects for hydrocarbon exploration. The analyses conducted include the calculation of petrophysical parameters, the analysis of pore-type and diagenesis controls on porosity values, and the determination of reservoir zones and hydrocarbon zones. The research methods include data conditioning, lithology determination and stratigraphic analysis, stratigraphic correlation, determination of petrophysical input parameters, petrophysical analysis, analysis of pore-type controls on porosity, and analysis of hydrocarbon reservoir zones. The results show that the Kujung-I Interval is divided into two lithological units, namely Interbedded Limestone and Shale (LS-1) and Limestone with Shale Interbeds (LS-2). Stratigraphic correlation shows a thinning of LS-1 and a thickening of LS-2 toward the northeast. Petrophysical analysis shows that the average Vsh values of LS-1 and LS-2 in limestone lithology are 0.138 and 0.100 v/v, respectively, with PHIE values of 0.180 and 0.145 v/v, and Sw values of 0.584 and 0.802 v/v. The analysis of pore-type controls on porosity indicates that high porosity is associated with leached porosity, moldic pores, and dissolution processes, whereas low porosity is associated with fracture pores, channel pores, unidentified pores, and recrystallization processes. The determination of reservoir zones and hydrocarbon zones indicates that all wells contain reservoir intervals and net pay, with the greatest net pay thickness in MZ-1 at 349.48 ft and the smallest in MZ-5 at 119.92 ft. Laterally, the reservoir zone thickens toward the northeast as limestone develops. The distribution of hydrocarbon zones in LS-2 tends to be concentrated in the upper part of the interval in the northeastern wells, but is more evenly distributed in the southwestern wells, whereas in LS-1, the distribution is more evenly spread in the northeast than in the southwest.

Kata Kunci : Cekungan Jawa Timur Utara, Formasi Kujung-I, petrofisika, tipe pori, zona reservoir hidrokarbon