EVALUASI DAN OPTIMASI INJEKSI AIR UNTUK PRESSURE MAINTENANCE PADA ZONA A RESERVOIR KARBONAT LAPANGAN RS

SETIAWAN, REDY (2023) EVALUASI DAN OPTIMASI INJEKSI AIR UNTUK PRESSURE MAINTENANCE PADA ZONA A RESERVOIR KARBONAT LAPANGAN RS. Masters thesis, UPN "Veteran" Yogyajarta.

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Abstract

iv
RINGKASAN
Lapangan RS merupakan lapangan minyak baru yang sedang berada dalam
tahapan pengembangan dengan reservoir carbonate sebagai zona produksi. Zona A
merupakan salah satu lapisan reservoir dengan estimasi jumlah cadangan minyak
terbesar yang telah diproduksi sejak bulan Oktober tahun 2019. Injeksi air mulai
dilakukan melalui satu sumur injeksi pada bulan November tahun 2020. Sampai
dengan bulan Desember tahun 2022, terdapat 8 sumur produksi (6 sumur aktif dan
2 sumur inactive) dengan kumulatif produksi minyak sebesar 3.64 MMSTB. Dari
data produksi yg diperoleh, diketahui bahwa terjadinya penurunan tekanan
reservoir inisial sebesar 3,400 psig menjadi 2,647 psig pada bulan Desember tahun
2022. Penurunan tekanan yang cukup signifikan tersebut merupakan indikasi
bahwa injeksi air belum optimal dalam mempertahankan tekanan reservoir.
Analisis lebih lanjut dan lebih detail mengenai evaluasi kinerja injeksi air sebagai
pressure maintenance dengan metode monitoring surveillance dan karakterisasi
reservoir menjadi bagian penting sebagai referensi pengembangan lapangan jangka
panjang agar Lapangan RS dapat mempertahankan tekanan reservoir dan
memberikan perolehan produksi minyak yang optimal.
Penelitian dibagi menjadi tiga tahap analisis yaitu evaluasi injeksi air
(pressure maintenance) surveillance; evaluasi karakteristik reservoir; dan optimasi
menggunakan simulasi reservoir. Analisis surveillance meliputi analisis performa
produksi dan injeksi; analisis performa tekanan; analisis voidage replacement ratio
(VRR); analisis Hall’s Plot dan Chan’s Diagnostic Plot. Evaluasi karakteristik
reservoir meliputi analisis terhadap jumlah cadangan sisa; jenis drive mechanism
yang bekerja; profil fasa pendesakan dalam reservoir berdasarkan analisis
fractional flow (Buckley-Leverett); profil kualitas reservoir dan heterogenitas
reservoir; serta kondisi tekanan reservoir Lapangan RS. Pemodelan material
balance digunakan sebagai simulasi awal untuk optimasi sumur injeksi dan prediksi
performa produksi.
Berdasarkan tahapan analisis surveillance, injeksi air pada reservoir Zona A
Lapangan RS belum optimal dalam mempertahankan tekanan reservoir dan
meningkatkan perolehan minyak. Berdasarkan evaluasi karakteristik reservoir,
Zona A pada Lapangan RS compatible untuk dilakukan optimasi injeksi air dengan
memperhatikan heterogenitas reservoir dan kualitas air injeksi. Optimasi injeksi air
dapat dilakukan untuk mempertahakan nilai voidage replacement ratio pada
kondisi setimbang (VRR=1). Berdasarkan production prediction model material
balance, reservoir Zona A mampu memproduksikan minyak dengan laju alir
sebesar 3038.36 BOPD; mampu mempertahankan tekanan reservoir sampai dengan
1679.28 psig; nilai water cut reservoir mencapai 77.82%; dan nilai cumulative oil
production sebesar 31.14MMSTB atau setara dengan 12.50% recovery factor.
Pemodelan reservoir 3 Dimensi perlu dilakukan untuk mensimulasikan skenario
lanjutan optimasi injeksi air sebagai pressure maintenance di lapangan RS.
Kata kunci: reservoir, injeksi air, pressure maintenance, karakterisasi reservoir,
model material balance
v
ABSTRACT
The RS field is a green oil field that is in development stage with a carbonate
reservoir as the interest zone. A zone is one of the reservoir zones of the field with
the highest oil reserve and has been produced since October 2019. A water injection
program has been applied through one injection well since November 2020. Until
December 2022, there are 8 production wells (6 active producers and 2 shut-in
wells) with 2.64 MMSTB of oil cumulative production. Based on production data,
the reservoir pressure is decreased from 3,400 psig tp 2,647 psig at cut-off date
(December 2020). The significant pressure decline is an indicator that the injection
program in A zone is not optimum yet in maintaining the reservoir pressure.
Therefore, a further detail and comprehensive analysis to evaluate and optimize the
pressure maintenance program through monitoring surveillance and reservoir
characterization is required. The objective is to optimize the pressure maintenance
program and to increase the oil recovery of A zone in RS field.
This study consists of three steps of analysis: the evaluation of existing water
injection (pressure maintenance) surveillance; reservoir characterization
evaluation; and reservoir simulation study. Surveillance analysis includes
production and injection performance analysis; pressure performance analysis;
voidage replacement ratio (VRR) analysis; Hall’s Plot analysis and Chan’s
Diagnostic Plot analysis. Reservoir characterization evaluation includes remaining
reserve evaluation; drive mechanism analysis; reservoir displacement profile
phase based on fractional flow analysis (Buckley-Leverett); quality and reservoir
heterogeneity; and reservoir pressure condition analysis. Material balance
modeling is used as an initial simulation for optimization of injection wells and
production performance prediction.
Based on surveillance analysis, water injection in the Zone A reservoir of the
RS Field, it is not yet optimal in maintaining reservoir pressure and increasing oil
recovery. Based on the evaluation of reservoir characteristics, Zone A in the RS
Field is compatible for optimization of water injection taking into account reservoir
heterogeneity and injection water quality. Water injection optimization can be done
to maintain the value of voidage replacement ratio at equilibrium conditions
(VRR=1). Based on production prediction model material balance, if produced with
VRR = 1, until the end of the contract (October 2039), the Zone A reservoir is
capable of producing oil with a flow rate of 3038.36 BOPD; capable of maintaining
reservoir pressure up to 1679.28 psig; water cut reservoir reached 77.82%; and
cumulative oil production is 31.14MMSTB or equivalent to 12.50% of recovery
factor. 3-D reservoir modelling is required to determine advanced scenarios of
water injection for pressure maintenance in RS field.
Keywords: reservoir, water injection, pressure maintenance, reservoir
characterization, reservoir simulation

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	reservoir, water injection, pressure maintenance, reservoir characterization, reservoir simulation
Subjects:	T Technology > T Technology (General)
Divisions:	Faculty of Engineering, Science and Mathematics > School of Engineering Sciences
Depositing User:	Eko Yuli
Date Deposited:	18 Dec 2023 04:11
Last Modified:	20 Dec 2023 03:02
URI:	http://eprints.upnyk.ac.id/id/eprint/38363

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