Judul: Kajian kinerja Surfaktan Mes (Metil Ester Sulfonat) dari Jarak Pagar (Jatropha Curcas L.) untuk enhanced waterflooding
Abstrak: Year by year, the production of petroleum decreases but its demand increases. The world will get the energy crisis if that condition happens continously. The main cause of low production of petroleum in Indonesia is the majority Indonesia’s oil wells being mature field/brown field and the discovery of new oil field in small scale. Indonesia focuses on maximize oil recovery in brown field because its oil production decreases naturally up 15% in total production. In recent years, the field of enhanced oil recovery has grown became more popular due to a combination of stagnant oil production and low recoveries by conventional methods. Many fields use unconventional method like enhanced oil recovery (EOR) which is tertiary oil recovery phase. One way of EOR is chemical flooding which uses surfactant for injection. Surfactant is injected to water and it is known as enhanced waterflooding. Generally, surfactant of petroleum sulfonates is used for oil recovery. This surfactant has many weaknesses such as resistance to water hardness, susceptible detergency to high salinity and being imported with expensive price. Due to these weaknesses, therefore it trigger to get surfactant substitute like MES (methyl ester sulfonates) that is synthesized by biooil. One of biooil is Jatropha oil. The study was aimed to know experimental of surfactant formula for enhanced waterflooding in fluida sample of oil field and synthetic core sandstone. The result showed that injection of surfactant 0,2 PV gave the influence differently to oil recovery. The best condition was surfactant 0,2 PV with the soaking time of 12 hours. This formula gave the highest of incremental total oil recovery 61,07%. The number were resulted from 47,73% waterflooding and 13,34% surfactant injection. Surfactant formula gave the good performance of compatibility, thermal stability, phase behavior and filtration test.
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Judul: Uji Kinerja Surfaktan MES (Metil Ester Sulfonat) dari Stearin Sawit untuk Enhanced Water Flooding
Abstrak: Surfactant has been widely used for the application of Enhanced Oil Recovery (EOR) by decreasing the interfacial tension. Recently, most of the surfactants that are still used are petrochemical surfactants. MES surfactant is a surfactant derived from renewable resources that can replace petrochemical surfactant and has many advantages. The study was conducted by formulating the surfactant solution, testing performance of the surfactant formula, and testing the core flooding. The results of the study showed that palm stearin MES surfactant was compatible to the water injection of Ty field. The formulation generated average number of interfacial tension formula up to 7.88E-03 dyne/cm, so the formulation met the expected number of IFT for EOR. The thermal stability test showed that palm stearin MES surfactant is heat resistant. It was proven by the low of IFT number increasing and the decreasing of both viscosity and density. Phase behavior showed that the phase between oil and surfactant were in the type II (-) or low phase. Core flooding test was done by differentiation of surfactant solution injection of 0.1PV, 0.2PV, 0.3PV and soaking for 12 hours. The Incremental recovery that is obtained after the surfactant solution injection was between 12-14% OOIP. Statistical analysis showed that the variation of pore volume that was injected has no significant effect to the oil recovery, but it increased with increasing of surfactant volume that was injected. Therefore, stearin MES surfactant has good performance to be applicated for enhanced waterflooding in the Ty field.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf