Annales Societatis Geologorum Poloniae (2011), vol. 81: 363–373. PETROPHYSICAL PROPER TIES OF THE PRE-MIO CENE ROCKS OF THE OUTER ZONE OF THE UKRAI NIAN CARPATHIAN FOREDEEP Ihor KUROVETS1, Hryhoriy PRYTULKA1, Andriy SHYRA1, Yulia SHUFLYAK1 & Tadeusz M. PERYT2 1 In sti tute of Ge ol ogy and Geo chem is try of Com bus ti ble Min er als of Na tional Acad emy of Sci ences of Ukraine, Naukova 3a, 79060 Lviv, Ukraine, e-mail: [email protected] 2 Polish Geo logi cal In sti tute – Nati onal Re search In sti tute, Rakowiecka 4, 00-975 Warszawa, Po land, e-mail: [email protected] Kurovets, I., Prytulka, H., Shyra, A., Shuflyak, Y. & Peryt, T. M., 2011. Petrophysical prop er ties of the pre-Mio cene rocks of the Outer Zone of the Ukrai nian Carpathian Foredeep. Annales Societatis Geologorum Poloniae, 81: 363–373. Ab stract: The pa per sum ma rizes the re sults of var i ous lab o ra tory stud ies of core ma te rial, in clud ing po ros ity, per meabil ity, lithological-fa cies and struc tural and tex tural char ac ter is tics of more than 1,000 samples of Me so- zoic and Palaeozoic rocks. The petrophysical param e ters of siliciclastic and carbon ate rocks are analysed for the to tal of sam ples rep re sent ing dif fer ent lithologies (lime stones vs. sandstones ) as well as for partic u lar strati gra- phic in ter vals (Up per and Lower Cre ta ceous, Up per Ju ras sic, Mid dle and Lower Ju ras sic, and Palaeozoic). The terrigenous rocks with inter gra nu lar po rosity and frac ture-cav ern ous car bonate rocks of reefal fa cies form the best res er voir rocks within the Me sozoic. The terrigenous rocks of frac tured and frac tured-po rous type that are con - trolled by the fault-block tec ton ics pro vide the best Palaeozoic and Ediacaran reser voirs. Key words: res er voir prop er ties, sand stone, lime stone, Palaeozoic, Me sozoic, Carpathian Foredeep, Ukraine. Manu script re ceived 12 May 2011, ac cepted 3 November 2011 IN TRO DUC TION Autochthonous de posit s of the Carpathian region, in - Derzhiv, Bohorodchany, and Davydeny, among the oth ers. cluding the substra te of the Outer Zone of the Carpathian In the core sam ples from the Cam brian sandstone s one can Foredeep, are consid ered to be the prime object for pros- ob serve oil shows, and during test ing of these sandstone s pection and ex plora ti on of oil and gas in western Ukraine the in signif i cant oil influx has been ob tained. Oil and gas (Krups’kiy, 2001; Kolodiy et al., 2004). Although Miocene shows in the Silu ria n depos it s have been obtai ned during (Sarmatian) sand stones rem ain the most im portant tar gets the well drill ing in ar eas: Derzhiv, Slobidka Lisna, Davy- for nat u ral gas (e.g., Kurovets et al., 2004), there is a num - deny, and Krasnoil’s’k. In parti cu lar, in the latter area, in ber of hy drocar bon fields re lated to the Upper Juras sic and boreholes 1 and 5 one could observe degas sing of the drill - Creta ceous depos it s in this zone; they in clude Kokhanivka, ing mud. Accord ing to archi val data, several zones of in- Sudova Vyshnia, and Orkhovychy oil fields; Letnia gas- creased hy dro car bon con tent were dis tin guished in the conden sat e field; and Rudky, Medenychy, Bilche-Volytsia, Cambrian sec tion in the Davydeny 1 borehole. Taking into Uhers’ko, Mala Horozhanna, Hrudiv and Vereschytsia gas ac count these data as well as the discov ery of the Uszkowce fields (Fig. 1) (Kotarba et al., 2011). In the north-west ern nat u ral gas field oc cur ring in the Or do vi cian–Si lu rian de- part of the Outer Zone, oil in flows from the Up per Juras sic posit s (Karnkowski, 1999) and of several gas fields (Lacho- limestone s were found in the Vyzhomlia, Tyniv and Nyklo- wice-Stryszawa, Zalesie, Niwiska) in the De vo nian de pos its vychi ar eas (Fig. 1). In the south-western part of the zone of SE Poland (Karnkowski, 1999), the Palaeozoic and Pre- un der the Carpathian Overthrust, the Lopushna oil field oc - cam brian depos it s of the Outer Zone of the Ukrai nian Car- curring in the Up per Juras sic , Cre taceous and Palaeogene pathian Foredeep are regarded to be prom ising for com mer- de pos its was dis cov ered. cial oil and gas explo ra ti on. The ar chi val data in di cate that oil and gas oc cur rences One of the prin cipal factors of the form ati on and pres er- were also re corded in the Palaeozoic de pos its in ar eas of vati on of hydro car bon depos it s is the avail abil ity of the res - Kokhanivka, Rudky, Mostys’ka, Chyzhevychy, Zaluzhany, ervoir rocks and fluid-im perm eable beds. The res ervoir pro- 364 I. KUROVETS ET AL. Fig. 1. Tec tonic map of the Carpathian oil- and gas-bear ing re gion (from Vul et al., 1998). 1 – 30: Fields of the Bilche-Volytsia oil- and gas-bear ing re gion perties of the Pre cam brian and Palaeozoic rocks of the GEO LOG I CAL FRAME WORK Ukrainian Carpathian Foredeep as well as its Meso zoic de - posit s were studied rarely (Kurovets, 2001; Lyzun et al., Figure 1 shows the tectoni c posi ti on of the Carpathian 2004). Therefore, we have analy sed reser voir proper ti es of oil- and gas-bearing re gion (Vul et al., 1998). The block Meso zoic and Palaeozoic rocks in the Outer Zone of the struc ture, the avail abil ity of multi-storey struc tural com - Ukrai nian Carpathian Foredeep aim ing to estab li sh the ba- plexes and the dipping of the eroded surface of the pre-Mio- sic geo log i cal fac tors con trol ling the ca pac ity-fil tra tion cha- cene strata to wards the Carpathians, in the form of sep a rate racteristic. steps across the system of longi tu di nal tectoni c frac tures, PETROPHYSICAL PROP ER TIES OF THE PRE-MIO CENE ROCKS 365 Fig. 2. SSW–NNE geo log i cal sec tion along A–A’ line in Fig. 1 (based on Vul et al., 1998) Ta ble 1 Petrophysical sec tion of the pre-Neogene of the Outer Zone of the Ukrai nian Carpathian Foredeep (based on archi val data and the origi nal result s shown in Table 2) are char ac ter is tic for the Outer Zone of the Ukrai nian Car- sion) where they occur di rectly un der the Mio cene form a- pathian Foredeep (Fig. 2; cf. Kotarba et al., 2011). tions and were encoun ter ed in many boreholes (Glushko & Within the limits of the Outer Zone of the Ukrai nian Car- Kruglov, eds, 1977; Stupka, 1993), in cluding sev eral wells pathian Foredeep, Me so zoic, Palaeozoic and Up per Pro tero - locat ed in the Chyzhky and Mostys’ka re gions near the bor- zoic de pos its oc cur be low the Mio cene (Ta ble 1), the latter der with Poland. However, as stressed by Bu³a and Habryn includ ing the depos it s assum ed so far to be of the Riphean (2011), the rocks con sidered to be Riphean in Ukraine are sim - age (Kruglov & Tsypko, eds, 1988; Stupka, 1993; Mizerski ilar to the Ediacaran flysch depos it s of the Ma³opolska Block & Stupka, 2005). These depos it s are widely distri buted in the in SE Poland, and in addi ti on their Ediacaran age is supporte d north-western part of the Outer Zone (Krukenychy Depres - by palynological studies of Jachowicz-Zdanowska (2011). 366 I. KUROVETS ET AL. In the north-east ern part, their dis tri bu tion is limited by overlain by the Miocene . Most secti ons exposed by bore- the Krakovets Fault, and towards the southwest the Edia- holes are known to occur in areas of Uhers’ko, Bilche- caran depos it s are covered by the Sambir unit and then by Volytsia, Pivnichni Medynychy and Letnia where their the Boryslav-Pokuttya unit and Skyba nappe of the Outer thickness is from 570 to 720 m. The Upper Creta ceous is Carpathians. The data of seis mic sur vey in di cate that the to - rep re sented by the Cenomanian–Maastrichtian strata (Pas- tal thick ness of the Ediacaran de pos its is sev eral kilo metres, ternak et al., 1987). and only its top part (maxi m um 199 m in the Tvirzha 3 bore - The Cenomanian is com posed of yellow-gre y and grey- hole) was drilled. green quartz-glauconitic sandstone s with an adm ixture of The Palaeozoic devel oped along the north-western mar- gravels and pebbles of black flints, and then the sandstone s gin of the Outer Zone and is com posed of the Cam brian, Or- are fol lowed by grey and yel low-grey sandy inoceramid do vi cian, Si lu rian and De vo nian sed i ments (Drygant, 2000).