Zero-one IP problems: Polyhedral descriptions & cutting plane procedures

A systematic way for tightening an IP formulation is by employing classes of linear inequalities that define facets of the convex hull of the feasible integer points of the respective problems. Describing as well as identifying these inequalities will help in the efficiency of the LP-based cutting plane methods. In this report, we review classes of inequalities that partially described zero-one poly topes such as the 0-1 knapsack polytope, the set packing polytope and the travelling salesman polytope. Facets or valid inequalities derived from the 0-1 knapsack and the set packing polytopes are algorithmically identifie

Using durian rind as bridging material to overcome fluid loss and lost circulation problems in drilling operations

Lost circulation is one of the drilling operational problems. It refers to the total or partial loss of drilling fluid into highly permeable zones or natural or induced fractures. This problem is likely to occur when the hydrostatic head pressure of drilling fluid in the hole exceeds the formation pressure. Today, managing lost circulation remains a significant challenge to oilwell drilling operations because it may contribute to high non-productive time. It is imperative to note that the overbalance pressure situation also can cause the invasion of mud filtrate into production zones which will result in formation damage. To address these problems, an experimental investigation has been done on durian rind as an alternative fluid loss and lost circulation materials in water-based mud. Durian rind was selected as a mud loss control material because it contains close to 20% pectin which may complement the formation of high quality mat-like bridges across openings of the formation. The test involved the use of standard mud testing equipment and a lost circulation test cell. Durian rind powder was prepared by cleaning and cutting the durian rind into small pieces of 1 to 2 cm, and then dried them in an oven at 60°C for 48 hours before grinding into five different sizes from coarse to ultra-fine while Hydro-plug, the commercial lost circulation material was supplied by Scomi Energy. The fluid loss test was conducted using a standard low pressure filter press while the bridging test was carried out at 100 psi of pressure difference and ambient temperature using a lost circulation cell. Fine durian in the water-based mud gave the best fluid loss control compared to coarse durian rind, fine and coarse Hydro-plug. The experimental results also showed that at 15 lb/bbl (42.8 kg/m3) optimum concentration, coarse and intermediate durian rind have outperformed Hydro-plug by showing an excellent control of mud losses in 1 and 2 mm simulated fractures

Perencanaan Program Hidrolika pada Sumur Eksplorasi F di Lapangan M

Salah satu tantangan dalam pemboran deepwater biaya sewa rig yang sangat tinggi,sehingga kegiatan pemboran diperlukan secepat mungkin untuk menghemat biaya. Sumureksplorasi F merupakan sumur yang terletak di Lapangan M dengan target kedalaman 14,030 ftpada struktur Ngimbang Karbonat. Dari studi G&G dan berdasarkan sumur offset dapat diketahuibahwa lapisan yang akan ditembus adalah Lidah Shale hingga kedalaman 4,650 ft, kemudianPaciran hingga kedalaman 5,660 ft, lalu Cepu Shale hingga kedalaman 10,030 ft, dan yangterakhir adalah Ngimbang Karbonat hingga kedalaman 14,030 ft. Terlihat bahwa ada banyakkemungkinan masalah terkait hole cleaning dikarenakan lapisan shale yang panjang danditambah dengan masalah mud window yang tipis. Untuk mengatasi masalah hole cleaning danmud window yang tipis, pada trayek 26” dilakukan pemompaan 2200 GPM dengan konsentrasicutting yang dijaga sebesar 10% dan ROP yang mampu dicapai adalah 291 fph. Kemudian padatrayek 17-½” dilakukan pemompaan 1600 GPM dengan konsentrasi cutting yang dijaga sebesar3% dan ROP yang mampu dicapai adalah 170 fph. Lalu pada trayek 14-¾” dilakukan pemompaan1300 GPM dengan konsentrasi cutting yang dijaga sebesar 3% dan ROP yang dapat dicapaisebesar 208 fph. Selanjutnya adalah pada trayek 12-¼” dilakukan pemompaan 1200 GPM dengankonsentrasi cutting yang dijaga sebesar 3% dan ROP yang mampu dicapai sebesar 306 fph. Lalupada trayek 10-7/8” dilakukan pemompaan sebesar 832 GPM dengan konsentrasi cutting yangdijaga sebesar 3% dan ROP yang dapat dicapai sebesar 285 fph. Dan trayek yang tera khiradalah 8-½” dimana dilakukan pemompaan sebesar 768GPM dimana dijaga agar konsentrasicutting sebesar 3% dengan ROP yang mampu dicapai adalah 433 fph. Penentuan lajupemompaan pada masing-masing trayek dilakukan berdasarkan beberapa parameter yangmenjadi acuan laju pemompaan maksimum diantaranya adalah flow regime di annulus, ECD danspesifikasi peralatan bawah permukaan khususnya BHA

PERTUMBUHAN DAN HASIL PAKCOY (Brassica rapa L.) TERHADAP PEMBERIAN BIOCHAR TEMPURUNG KELAPA PADA TANAH GAMBUT PEDALAMAN: Application of Coconut Shell Biochar for Increasing The Growth and Yield of Pakcoy (Brassica rapa L.) on Peat Land

The purpose of this experiment was to study the growth and yield of pakcoy  (Brassica rapa L.) the giving of coconut shell  biochar on peat land. This research was conducted from June to August 2022. This research was conducted in a plastic house located on Jl. Haka, Panarung Village, Pahandut District, Central Kalimantan. This study used Randomized Compete Design (RCD) of single factor that was coconut shell  biochar consisting of 5 levels of treatment namely B0 (0 ton ha-1), B1 (4 ton ha-1),  B2 (6 ton ha-1), B3 (8 ton ha-1), and B4 (10 ton ha-1). The results showed that the application of coconut shell biochar had a significant effect on the growth and yield of pakcoy plants on peat land. Application coconut shell biochar dose of  B4 = 10 ton ha-1 (113.6 g. polybag-1) was the best treatment for the growth and yield of pakcoy plants on peat land with an average plant fresh weight of 91.92 g-1

Jatropha curcas as a potential plant for bauxite phytoremediation

Abandon bauxite mining sites can cause serious environmental problems, such as poor soil quality, air pollution, erosion and flood. Jatropha curcas could possibly be used to remediate barren bauxite mining sites. The objective of this study was to study the growth performance of J. curcas on top soil (control) and bauxite mined soil. Observation of the plant growth was recorded weekly, including days to rooting, number of roots per cutting, days to new bud opening, number of shoots per cutting, number of leaves per cutting, plant height and chlorophyll content. Data collected on the growth performance of J. curcas were analyzed using SPSS 11.5 for Windows Standard Version. Based on the results obtained, J. curcas could thrive and grow on bauxite mined soil as it has higher significantly difference in number of leaves and plant height after growing on bauxite mined soil. Therefore, J. curcas is suitable for phytoremediation, in order to solve the environmental problems that occur on the bauxite mined sit

Diversity and Abundance of Plankton in Mangrove Waters

The mangrove forest is an environment that is very rich in nutrients and it becomes an important element for plankton growth. This article aims to determine the diversity and abundance of plankton species in the mangrove area. The method used in this writing is a literature study, by exploring written sources in the form of books, articles, journals, or other documents relevant to the problem being presented. The information obtained from the literature study can be used as a reference to strengthen the existing arguments. The results of the writing show that the abundance and diversity of plankton in mangrove waters are strongly influenced by the physical and chemical conditions of the water, local conditions, tides, zoning, and mangrove density. In general, phytoplankton from the Bacillariophyceae class dominate mangrove waters compared to zooplankton. A mangrove forest management strategy needs to be implemented so that it can function for organisms and the surrounding environment

Evaluasi Penyemenan Casing Liner 7” pada Sumur X-1 dan Y-1 Blok Lmg

Penyemenan primer merupakan hal yang mutlak dilakukan pada setiap sumur minyak dan gas.Mengingat pentingnya kualitas penyemenan primer maka harus memenuhi standar ketentuan yangberlaku. Apabila hasil dari kualitas penyemenan tidak baik maka semen tidak dapat menjalankanfungsinya sebagaimana mestinya. Seperti melindungi casing dari fluida korosif, menahan tekananformasi, dan sebagai media untuk jalur komunikasi antara formasi dengan sumur saat diperforasi.Evaluasi penyemenan pada casing liner 7” ini menggunakan peralatan logging yaitu Cement BondLog (CBL) dan Segmented Bond Tool (SBT). Hasil logging CBL-SBT dianalisa meliputi pembacaanamplitude, attenuation, cement map dan SBT wave. Dari hasil evaluasi penyemenan antara sumur X-1 dan Y-1 ditemukan perbedaan ikatan semen antara sumur X-1 dan Y-1 padahal sepanjangkedalaman casing liner 7” sumur X-1 dan Y-1 memiliki jenis formasi reservoir dan karakter reservoiryang sama serta dengan prosedur penyemenan yang sama terhadap kedua sumur tersebutseharusnya sumur X-1 dan Y-1 memiliki hasil penyemenan yang tidak jauh berbeda. Banyak faktoryang mempengaruhi kualitas dari hasil penyemenan, diantaranya: kondisi lubang bor, ketepatandalam perhitungan bubur semen baik aditif, total fluida, dan total sak semen, serta pengalaman dariahli penyemenan

Evaluasi Pemakaian Bit 6-1/8” di Sumur Dh-10 dan Dhx-4untuk Pemilihan Bit pada Lapisan Basementlapangan Dhp

Dalam pencarian minyak dan gas bumi, kini tidak hanya dilakukan pada batuan sedimen. Namun,kini pencarian minyak dan gas bumi juga dilakukan pada batuan beku dan batuan metamorf.Batuan beku dan metamorf ini biasanya terdapat pada formasi Basement, batuan ini memilikikekerasan antara medium sampai sangat keras. Hal ini menjadikan alasan betapa pentingnyapemilihan perlatan pemboran yang digunakan, khususnya pahat/bit. Pada lapangan DHP terdapatdua sumur yang menembus lapisan Basement yaitu sumur DH-10 dan DHX-4. Kedua sumurtersebut menggunakan bit yang berbeda – beda, untuk itu dilakukan evaluasi pemakaian dari bityang digunakan pada kedua sumur tersebut untuk mengetahui bit apa yang seperti apa yangcocok untuk digunakan pada lapisan Basement di Lapangan DHP