PROBABILITYCLASSESANDGEOLOGICALEVENTSINGEOLOGICALPROBABILITYCALCULATIONVJEROJATNOSNIRAZRED.doc

probability classes and geological events in geological probability calculationvjerojatnosni razredi i geoloki dogaaji u izraunu geoloke vjerojatnostiauthor:tomislav malvi1, miro urekovi1 i igor rusan21ina-oil industry plc., e&p of oil and gas, reservoir engineering & field development department, ubieva 29, 10000 zagreb2ina-oil industry plc., e&p of oil and gas, exploration department, ubieva 29, 10000 zagrebkey words: geological probability, categories, events, probability classes, pannonian basinkljune rijei: geoloka vjerojatnost, kategorije,dogaaji, vjerojatnosni razredi, panonski bazensaetak:u radu su opisani temeljni principi izraunavanja geoloke vjerojatnosti otkria leita ugljikovodika. prikazana metodologija primijenjena je za procjenu potencijalnog otkria u hrvatskom dijelu panonskog bazena. upotrijebljen je deterministiki pristup koji ukljuuje pet geolokih kategorija (zamku, rezervoar, matine stijene, migraciju i ouvanje ugljikovodika), procjenjujui na taj nain geoloke dogaaje kojima je odreena geoloka graa naftnog sustava. nainjena je znatna redukcija vjerojatnosnih razreda te je izraun mogue provjeriti na razliitim lokalitetima ili stratigrafskim jedinicama za koje je nainjen proraun. odabrani vjerojatnosni razredi ukljuuju pet numerikih i tekstualnih vrijednosti, i to redom: 1.00 za dokazani, 0.75 za vrlo pouzdano odreen dogaaj, 0.50 za prilino pouzdan, 0.25 za nepouzdani te 0.05 za neopaeni ili nepostojei geoloki dogaaj. metodologija je transparenta, odnosno moe jednostavno biti primijenjena u gotovo bilo kojem dijelu panonskog bazenskog sustava.abstract:this paper considers the basic principles of geological probability calculation for hydrocarbon reservoir. presented methodology is applied for evaluation of potential hydrocarbon discovery in croatian part of pannonian basin. applied deterministic approach included five geological categories (traps, reservoirs, source rocks, migration and hydrocarbon preservation), estimating geological events that could describe geological settings of petroleum systems. significant reduction of probability classes make possible easily check different plays or prospects that could be estimated. applied probability classes included five numerical and textual values as follows: 1.00 for proven, 0.75 for highly reliable, 0.50 for fairly reliable, 0.25 for unreliable and 0.05 for impossible prediction or missing geological event. calculation procedure is made in the form of freeware computer program. such transparent methodology can easily be applied in almost any part of pannonian basin system.introductionthe goal of geological probability calculation is finding an appropriate numerical value, which can describe the probability of new hydrocarbon discoveries on observed area. this procedure could be applied both in exploration and/or development of hydrocarbon reservoirs.geological probability is defined as multiplication of the main geological factors or categories that define petroleum system. reliability of data has the extraordinary importance. there is always balance between invested funds and collected data depends on reliability of geological database, predicted size of potential discovery and company budget. first step in that process of several activities is estimation of geological probability, calculated from acquired data.testing dataset was collected from regional studies published for southern part of the drava depression and the bjelovar subdepression (malvi, 1998, 2003). this mature area included all relevant geological categories stratigraphically described in neogene and pre-neogene sediments (figure 1). thickness of neogene-quaternary clastic sediments is mostly up to 3000 meters, with mesozoic and palaeozoic rocks in the basement. the highest hydrocarbon potential is attached to lower and middle miocene coarse-grained clastites, accompanied with fractured and weathered basement rocks in unique hydrodynamic unit. lower and middle miocene reservoirs and traps are relative shallow, located between 800 and 1500 meters. the second reservoir unit consists of lower pontian sandstone members. unfortunately, these sandstones are characterized with very instable reservoir properties and depth shallower than 1000 meters, what makes possible to hydrocarbon escaping along the faults as well as water degradation.figure 1. categories of hydrocarbon system in analyzed area (malvi et al., 2005)source rocks (ottnangian to badenian ages) are assumed inside two major synclines of subdepression, on depth between 1600 and 2500 meters. catagenesis phase is reached only in the deepest parts, and it is why significant part of hydrocarbons migrated from northwestern part of the drava depression. there are proven source rocks represented by mudstones, marls and siltites of lower miocene to badenian age at depths greater than 3000 meters (baric et al., 1998). the potential for new hydrocarbon systems was calculated via five independent geological categories: (i) structures; (ii) reservoirs; (iii) migration; (iv) source rocks; and (v) preservation of hydrocarbons. calculation can be done for any play or prospect. brown and rose (2001) defined play as operational and prospect as economic unit. rose (2001) and white (1992) described play as several, geologically similar, fields, discoveries or prospects. here, the term play was used as substitution for stratigraphic interval(s) where are already discovered economic hydrocarbon reserves. there are two such plays: (a) basement rocks and miocene breccia and (c) pannonian and pontian sandstones. mostly structural traps inside analyzed area were selected from structural maps and palinspastic sections (malvic, 1998, 2003). geological probabilities via categoriesgeological probability calculation procedures are well-known and simple tool for petroleum system description for decades. generally, such calculation could be done allowing expert(s) to estimate probabilities of particular geological categories, using numerical values in the range 0.0-1.0 and using geological probability tables published for different petroleum provinces around the world. the approach applied in this paper was based on evaluation of five geological categories (according white, 1993): category 1: probability of trap; category 2: probability of reservoir; category 3: probability of source rocks; category 4: probability of migration; category 5: probability of hc preservation.multiplication of these categories final result in probability of success of discovery:(1)the appropriate geological database, including characteristic geological categories and events, was derived from available dataset published in earlier regional study of the bjelovar subdepression (malvic, 1998, 2003). this database was organized in access, and linked to executive computer code programmed in delphitm language (brki et al., 2006), called geoprob modeling 1.0.2 (figure 3). the program is freeware.figure 3. pos calculation in geoprob modeling 1.0.2each geological category could be evaluated from the different type of data, with very various qualities. seismic mostly plays major role as base for structural and sometimes also stratigraphic interpretation. addition important information is eventually existing production in analyzed play or close to estimated prospect. if such production exists, potential discovery can be classified as potential (not only hypothetical). probability classesgeological categories are always described through several probability classes). each class has unique discrete numerical values in the range 0 and 1 that describes probability to occur selected event(s). we selected (only) five classes to correlate probability event by classification of reserves. as we know reserves as proven, possible, speculative and so on, there is deeply geological sense that such ranking cab be also applied in determination of petroleum system that include such reserves. it means that geological event or category can also be proven, highly or fairly probable, hypothetical or missing. according to such qualification geological events are described as: 1.00 for event in play/prospect described as “proven”; 0.75 for event in play/prospect described as “highly reliable prediction”; 0.50 for event in play/prospect described as “fairly reliable prediction”; 0.25 for event in play/prospect described as “unreliable prediction”; 0.05 for event in play/prospect described as “missing/undefined parameter”.there is selected 62 geological events (and more than 100 options) though 5 categories and special database (figure 3), as part of computer program geoprob 1.0.2.figure 3. database with 62 geological events classified in five probability classesdiscussionpresent computer program can be used for geological probability calculation in any neogene petroleum zone (play or prospect) in the southern part of drava depression or the bjelovar subdepression. also, it can be applied in both in the entire sava and drava depressions, without any or with minor modifications represented in carefully re-selection of geological events.the proposed geological database represents is based on the five probability classes: 1.00 (proven), 0.75 (highly reliable predicted), 0.50 (fairly reliable predicted), 0.25 (unreliable predicted) and 0.05 (missing geological event).it would be useful presented methodology upgrades by additional tool for estimation of seismic and production data. both of these two groups included important information on reliability of data used for geological events selection.referencesbrki, n., t. malvi and i. rusan, 2006, geoprob modeling 1.0 (computer program): zagreb, (freeware).brown, p. j., and p. r. rose, 2001, plays and concessions a straightforward method for assessing volumes, value, and chance (poster): aapg annual meeting, search and discovery article #40024.malvi, t., 1998, strukturni i tektonski odnosi, te znaajke ugljikovodika ire okolice naftnoga polja galovac-pavljani: zagreb, master thesis, faculty of mining, geology and petroleum engineering, 111 p.malvi, t., 2003, oil-geological relations and probability of discovering new hydrocarbon reserves in the bjelovar sag: zagreb, ph.d. dissertation, faculty of mining, geology and petroleum engineering, 123 p.malvi, t., j. veli, and z. peh, 2005, qualitative-quantitative analyses of the influence of depth and lithological composition on lower pontian sandstone porosity in the central part of bjelovar sag (croatia): geologia croatica, v. 58, p. 73-85.rose, p. r., 2001, risk analysis and management of petroleum exploration ventures: tulsa, aapg methods in exploration series, 12, 164 p. white, d. a., 1992, selecting and assessing plays, in r. steinmets, ed., aapg business of petroleum exploration: treatise of petroleum geology, chapter 8: tulsa, p. 87-94.white, d. a., 1993, geologic risking guide for prospects and plays: aapg bulletin, v. 77, p. 2048-2061.我的大学爱情观1、什么是大学爱情：大学是一个相对宽松，时间自由，自己支配的环境，也正因为这样，培植爱情之花最肥沃的土地。大学生恋爱一直是大学校园的热门话题，恋爱和学业也就自然成为了大学生在校期间面对的两个主要问题。恋爱关系处理得好、正确，健康，可以成为学习和事业的催化剂，使人学习努力、成绩上升；恋爱关系处理的不当，不健康，可能分散精力、浪费时间、情绪波动、成绩下降。因此，大学生的恋爱观必须树立在健康之上，并且树立正确的恋爱观是十分有必要的。因此我从下面几方面谈谈自己的对大学爱情观。2、什么是健康的爱情：1) 尊重对方，不显示对爱情的占有欲，不把爱情放第一位，不痴情过分；2) 理解对方，互相关心，互相支持，互相鼓励，并以对方的幸福为自己的满足; 3) 是彼此独立的前提下结合；3、什么是不健康的爱情：1)盲目的约会，忽视了学业;2)过于痴情，一味地要求对方表露爱的情怀，这种爱情常有病态的夸张;3)缺乏体贴怜爱之心，只表现自己强烈的占有欲;4)偏重于外表的追求;4、大学生处理两人的在爱情观需要三思：1. 不影响学习：大学恋爱可以说是一种必要的经历，学习是大学的基本和主要任务，这两者之间有错综复杂的关系，有的学生因为爱情，过分的忽视了学习，把感情放在第一位；学习的时候就认真的去学，不要去想爱情中的事，谈恋爱的时候用心去谈，也可以交流下学习，互相鼓励，共同进步。2. 有足够的精力：大学生活，说忙也会很忙，但说轻松也是相对会轻松的！大学生恋爱必须合理安排自身的精力，忙于学习的同时不能因为感情的事情分心，不能在学习期间，放弃学习而去谈感情，把握合理的精力，分配好学习和感情。3、 有合理的时间；大学时