APERTURA CONVEGNOModera Luigia Ierace

3^ sessionePERICOLOSITÀ

GEOLOGICA GEOINGEGNERIA

modera: Mary William

haydaral-shukri

et alii

213

Induced seismicity a result of fluid injection and oil shale frackingH. Al-Shukri1, N. Abd1, and H. Mahdi1

(1) Department of Applied Science, University of Arkansas at Little Rock, Little Rock, AR 72204, hjalshukri@ualr.edu

Atti del 1º Congresso dell’Ordine dei Geologi di Basilicata,“Ricerca, Sviluppo ed Utilizzo delle Fonti Fossili: Il Ruolo del Geologo”, Potenza, 30 Novembre - 2 Dicembre 2012.

For the last few years, the widespread oil shale in the central United States has been heavily prospected as a major source for hydrocarbon energy. The natural gas from the impermeable shale is extracted by increasing its permeability such that the natural gasslowly begins to flowand collect at the surface. This is accomplished through a process called hydrofracturing (fracking) of the shale. Water mixed with toxic chemicals and sandy particles is pressured into the shale to fracture it allowing the natural gas to seep through the permanently opened crack. In Arkansas, hundreds of these wells have been drilled following strict rules and regulations and carefully monitored by the Arkansas Oil and Gas Commission. The toxic by product fluids of the fracking process must be carefully disposed of or treated. One method of disposing of these by products is to inject them deep into the subsurface in zones that are substantially deeper than the oil shale formations. A requirement for the fluid injection permit was to monitor the possibility of induced seismicity. The reason for such a requirement was that the region has experienced a number of naturally occurring swarms of earthquakes, some of them of magnitudes as high as 4.5. The first monitored swarm took place in 1982 and lasted for a few years; the second swarm occurred in 2001.Large numbers of deep wells have been used to inject the toxic fluids into permeable formations at depths ranging from about 1.5 to more than 3 kilometers. An impermeable formation is placed over the permeable one to prevent the fluids from seeping back to the surface. A seven element high-frequency array was installed to supplement the existing permanent regional stations. Each element consisted of three-component 4.5 Hz geophone. The array has an aperture of 3 kilometers and is centered on a disposal well located 5 kilometers from the historic natural seismicity. In addition to the well that the array monitors, there are five more disposal wells located to the west and north of the array within a distance of 10 kilometers. After the injection started in these wells, almost 10,000 earthquakes took place over a period of about 18 months. The magnitude range for these events was between -1.5 to 4.7. Human analysts located more than 3500. To improve location accuracy, earthquakes of magnitude 2.0 and larger were again located using other stations in the area. A linear narrow feature of seismicity that extends in a northeast - southwest direction located about 10 kilometers to the northwest of the array became clearly visible. The pressured fluids seem to have made their way to a critically stressed fault, causing the pore pressure in the fault area to be substantially changed. The earthquake activity immediately reduced from hundreds per month to only a few after the injections in two wells were suspended. Earthquake data clearly indicate that only a few injection wells triggered the induced seismicity. Recently, a similar seismicity induced in the state of Oklahoma, including a 5.6 magnitude earthquake which produced a considerable and widespread damage.

3^ sessionePERICOLOSITÀ

GEOLOGICA GEOINGEGNERIA

modera: Mary William

1° CONGRESSO DEI GEOLOGI DI BASILICATA

IL RUOLO DEL GEOLOGO

1° CONGRESSO DEI GEOLOGI DI BASILICATA

IL RUOLO DEL GEOLOGO

www.geologibasilicata.it/http://congresso.geologibasilicata.it/2012/ORDINE DEI GEOLOGI

DI BASILICATA

RICERCA, SVILUPPO ED UTILIZZODELLE FONTI FOSSILI

1° CONGRESSO DEI GEOLOGI DI BASILICATA

IL RUOLO DEL GEOLOGO

1° CONGRESSO DEI GEOLOGI DI BASILICATA

IL RUOLO DEL GEOLOGO

30 NOVEMBRE > Potenza01 DICEMBRE > Potenza02 DICEMBRE > Marsico Nuovo

Teatro Stabile, Piazza M. Pagano

Sede Parco Nazionale dell’Appennino Lucano-Val d’Agri-Lagonegrese

ATTI DEL CONGRESSO

SEGRETERIA ORGANIZZATIVAORDINE DEI GEOLOGI DI BASILICATA

Via Zara 114 - PotenzaTel: 0971.35940, Fax: 0971.26352congresso@geologibasilicata.it

Responsabile: Sig.ra Angela Rubolino

Ministero dello Sviluppo Economico

Spon

soriz

zato

da:

Con l’Alto Patronato di: Presidenza della Repubblica Italiana

E il Patrocinio di: Presidenza del Consiglio dei Ministri

COMITATO PROMOTORE| Geol. Carlo Accetta, Geol. Raffaele Carbone, Geol. Filippo Cristallo, Geol. Franco Guglielmelli, Geol. Domenico Laviola, Geol. Maurizio Lazzari, Geol. Raffaele Nardone, Geol. Nunzio Oriolo, Geol. Mary William

COMITATO ORGANIZZATORE|Geol. Raffaele Nardone - Coordinatore, Geol. Annamaria Andresini, Geol. Maurizio Lazzari, Geol. Nunzio Oriolo, Geol. Mary William

COMITATO SCIENTIFICO|Dott. Raffaele Nardone - Coordinatore, Dott. Fabrizio Agosta, Dott. Mario Bentivenga, Dott. Claudio Berardi, Dott. Gerardo Colangelo, Ing. Ersilia Di Muro, Arch. Vincenzo L. Fogliano, Dott. Ivo Giano, Dott. Fabrizio Gizzi, Dott. Vincenzo Lapenna, Dott. Maurizio Lazzari, Dott. Sergio Longhitano, Ing. Maria Marino, Prof. Marco Mucciarelli, Dott. Lucia Possidente, Prof. Giacomo Prosser, Prof. Marcello Schiattarella, Prof. Vincenzo Simeone, Prof. Marcello Tropeano, Dott. Maria Pia Vaccaro, Dott. Donato Viggiano.

Tre intense giornate di sessioni ed interventi organizzate per i tecnici di tutti gli Ordini e Collegi, Operatori del settore Oil&Gas, Top Manager, Amministratori, Dirigenti e Funzionari della Pubblica Amministrazione, Studenti.L’obiettivo primario è quello di focalizzare l’attenzione sul ruolo che il geologo ha assunto in relazione allo sfruttamento compatibile e sostenibile delle fonti fossili naturali. La tematica verrà affrontata grazie all’intervento di relatori di altissimo livello tecnico ed istituzionale, con interessanti dibatt i t i ed una tavola rotonda sul la gest ione ambientale e formazione professionale.

Proprietà letteraria riservataEditore

1a edizione: 2013

Tutti le immagini sono il frutto della ricerca dei relatori e quindi sono utilizzate in questa pubblicazione ad esclusivo scopo didattico e divulgativo.

PRESIDENZA DEL CONGRESSODott. Raffaele Nardone

RESPONSABILE ATTI CONGRESSUALIDott. Raffaele Nardone