Special features of fracture network in Iranian fractured reservoirs

U raspucanim ležištima nafte zbog postojanja dva različita tipa porozne sredine, nazvane blokovi matriksa i pukotine, postoji više vrsti ponašanja ležišta. Zbog kompleksnosti strukture raspucanih ležišta, pridobivanje nafte je rezultat kombinacija nekoliko mehanizama proizvodnje kao što su gravitacijsko dreniranje i apsorpcija. Kapilarne i gravitacijske sile su dvije glavne sile koje kontroliraju ove mehanizme proizvodnje. Ovaj rad je usredotočen na utjecaj kapilarnog tlaka pukotina koji je različit od nule, relativnu propusnost pora koje nisu pravocrtne, pojavu reinfiltracije, visinu bloka matriksa i ponašanje aktivnih mehanizama u raspucanim ležištima za vrijeme prirodnog iscrpljivanja ležišta i injektiranja nemješljivog plina. Terenske studije simulacije polja napravljene su korištenjem simulatora ECLIPSE s formulacijom obične sirove nafte i opcijom dvostruke poroznosti. Rezultati simulatora, obzirom na relativnu propusnost pora koje nisu pravocrtne, pokazuju da utjecaj tog parametra na ponašanje ležišta ovisi ne samo o fizičkim svojstvima pukotina već i o kapilarnom tlaku praga matriksa i visini bloka matriksa. Rezultati simulacije pokazuju da je na pridobivanje nafte utjecao, u rasponu od 1% do 2%, razmatrani kapilarni tlak praga matriksa od 0,007 bara (0,1 psi) do 0,214 bara (3,1 psi). Isto tako na pridobivanje nafte utječe, u rasponu od 1,5% do 0,5%, razmatrana visina bloka matriksa od 4,57 m (15 f5) do 18,29 m (60 ft). Naši rezultati simulacije sugeriraju da je za raspucana ležišta s malom visinom bloka ili velikim kapilarnim tlakom praga matriksa, neophodno iznaći adekvatnu, od nule različitu, krivulju kapilarnog tlaka pukotina. Nakon toga smo proučili djelovanje relativne propusnosti zakrivljenih pora na ponašanje ležišta. Rezultati su istaknuli ovisnost utjecaja relativne propusnosti nelinearnih pukotina na visinu bloka matriksa. Rezultati simulacije dobiveni primjenom različitih visina bloka matriksa pokazuju povećanje iscrpka u rasponu od 2,3% do 5,2%, primjenom injektiranja nemješljivog plina. Stoga su ovi rezultati pokazali da ležišta s najvišim blokom matriksa mogu biti dobri kandidati za primjenu injektiranja nemješljivog plina.Due to the presence of two different types of porous media, namely matrix blocks and fractures; there are varieties of reservoir performance behaviors in fractured oil reservoirs. Because of this complex structure of fractured reservoirs, oil recovery is the result of the combination of several production mechanisms such as gravity drainage and imbibition. Two main forces controlling these production mechanisms are capillary and gravity forces. This work is focused on the influence of non-zero fracture capillary pressure, non-straight line fracture relative permeability, reinfiltration phenomenon and matrix block height on the performance of active mechanisms in fractured reservoirs during natural depletion and immiscible gas injection project. The field simulation studies were performed using ECLIPSE commercial simulator with black oil formulation and dual porosity option. Simulator results considering non-zero fracture capillary pressure indicated that the influence of this parameter on reservoir performance depended not only on fracture physical properties, but also it depended on matrix threshold capillary pressure and matrix block height. Simulation results indicated that oil recovery was affected by the range from 1% to 2% considering matrix threshold capillary pressure of 0.1 psi (0.007 bar) to 3.1 psi (0.214 bar). Also oil recovery was affected by the range from 1.5% to 0.5% considering matrix block heights of 15 ft (4.57 m) to 60 ft (18.29 m). Our simulation results suggest that for the fractured reservoirs with small block heights or with large matrix threshold capillary pressure, the appropriate non-zero fracture capillary pressure curve is necessary. Subsequently we have investigated the effect of non-straight line fracture relative permeability on reservoir performance. The results emphasized that the matrix block height depended on the influence of linear line fracture relative permeability. Simulation results acquired by applying different matrix block heights indicated the enhancement in oil recovery by immiscible gas injection in the range from 2.3% to 5.2% considering matrix block heights of 15 ft (4.57 m) to 60 ft (18.29 m). Hence, these results showed that the fractured reservoirs with the highest matrix block heights could be good candidates for implementing the immiscible gas injection operation

Effect of Drilling Fluid Properties on Rate of Penetration

Zadaća ovoga rada je odrediti učinak svojstava bušačih fluida na brzinu bušenja u ležištu koristeći dnevne izvještaje bušenja. Na osnovi naših studija na terenu, slijedeća svojstva bušačih fluida u nejednakom omjeru utječu na brzinu bušenja: težina isplake, plastična viskoznost i koncentracija krutih čestica. Rezultat ove studije pokazuje da je čisti učinak svojstava bušačeg fluida na brzinu bušenja manji no što se smatralo. Brzina bušenja smanjuje se povećanjem plastične viskoznosti, koncentracije krutih čestica i težine isplake. Smanjenje brzine bušenja više se pripisuje povećanju dubine, zato što se povećanjem dubine povećava čvrstoća stijene i smanjuje poroznost.The scope of this work is to determine the effect of drilling fluid properties on penetration rate in a field using daily drilling reports. Based on our field studies the following drilling fluid properties affect penetration rate to varying degrees: mud weight, plastic viscosity and solid content. The result of this study shows that the net effect of drilling fluid properties on penetration rate is less than what it thought to be. Penetration rate is decreased by increasing plastic viscosity, solid content and mud weight. Decreasing the penetration rate is more attributed to increase of depth, because by increasing the depth, rock strength increases and porosity decreases

Interaction between Injection Points during Hydraulic Fracturing

We present a model of the hydraulic fracturing of heterogeneous poroelastic media. The formalism is an effective continuum model that captures the coupled dynamics of the fluid pressure and the fractured rock matrix and models both the tensile and shear failure of the rock. As an application of the formalism, we study the geomechanical stress interaction between two injection points during hydraulic fracturing (hydrofracking) and how this interaction influences the fracturing process. For injection points that are separated by less than a critical correlation length, we find that the fracturing process around each point is strongly correlated with the position of the neighboring point. The magnitude of the correlation length depends on the degree of heterogeneity of the rock and is on the order of 30-45 m for rocks with low permeabilities. In the strongly correlated regime, we predict a novel effective fracture-force that attracts the fractures toward the neighboring injection point.Comment: Submitte

TGF-β and Iron Differently Alter HBV Replication in Human Hepatocytes through TGF-β/BMP Signaling and Cellular MicroRNA Expression

The nature of host-virus interactions in hepatitis B virus infection is incompletely understood. Since soluble factors, e.g., cytokines and metals, may exacerbate liver injury in chronic hepatitis, we considered that defining the effects of receptor-mediated signaling upon viral replication will be significant. Consequently, we studied effects of iron or TGF-β-induced TGF-β/BMP signaling in the HepG2 2.2.15 cell model of hepatitis B virus replication. We found iron and TGF-β increased hepcidin mRNA expression or TGF-β receptor kinase activity, respectively, which indicated that 2.2.15 cells responded appropriately to these substances. However, iron increased but TGF-β decreased hepatitis B virus mRNA and DNA expression. TGF-β induced expression at the mRNA level of multiple TGF-β/BMP pathway genes. This change was not observed in iron-treated cells. On the other hand, presence of SMAD proteins in iron or TGF-β-treated cells, including of SMAD4, did confirm convergence of TGF-β/BMP signaling pathways under these conditions. Since transcription factors in TGF-β/BMP signaling pathways could not have directly targeted hepatitis B virus itself, we studied whether iron or TGF-β exerted their effects through alternative mechanisms, such as by involvement of antiviral cellular microRNAs. We discovered cellular microRNA expression profiles were significantly different in iron or TGF-β-treated cells compared with untreated control cells. In many cases, exposure to iron or TGF-β changed microRNA expression in opposite directions. Introduction in cells of sequences representing such differentially expressed microRNAs, e.g., hsa-miR-125a-5p and -151-5p, even reproduced effects on virus replication of iron- or TGF-β. We surmised that TGF-β/BMP pathway members, i.e., SMADs, likely governed iron or TGF-β-induced microRNA expression. Iron may have mediated Drosha/DGCR8/heme-mediated processing of microRNAs. In turn, cellular microRNAs regulated replication of hepatitis B virus in iron or TGF-β-treated cells. This knowledge should advance studies of mechanisms in viral-host interactions, hepatic injury, and therapeutic developments for hepatitis B

Efficacy of Combined Therapy with Amantadine, Oseltamivir, and Ribavirin In Vivo against Susceptible and Amantadine-Resistant Influenza A Viruses

The limited efficacy of existing antiviral therapies for influenza – coupled with widespread baseline antiviral resistance – highlights the urgent need for more effective therapy. We describe a triple combination antiviral drug (TCAD) regimen composed of amantadine, oseltamivir, and ribavirin that is highly efficacious at reducing mortality and weight loss in mouse models of influenza infection. TCAD therapy was superior to dual and single drug regimens in mice infected with drug-susceptible, low pathogenic A/H5N1 (A/Duck/MN/1525/81) and amantadine-resistant 2009 A/H1N1 influenza (A/California/04/09). Treatment with TCAD afforded >90% survival in mice infected with both viruses, whereas treatment with dual and single drug regimens resulted in 0% to 60% survival. Importantly, amantadine had no activity as monotherapy against the amantadine-resistant virus, but demonstrated dose-dependent protection in combination with oseltamivir and ribavirin, indicative that amantadine's activity had been restored in the context of TCAD therapy. Furthermore, TCAD therapy provided survival benefit when treatment was delayed until 72 hours post-infection, whereas oseltamivir monotherapy was not protective after 24 hours post-infection. These findings demonstrate in vivo efficacy of TCAD therapy and confirm previous reports of the synergy and broad spectrum activity of TCAD therapy against susceptible and resistant influenza strains in vitro

Uterine Septum Dimensions in Patients with Infertility and Recurrent Abortion and the Outcomes of Hystroscopic Metroplasty

Abstract: Background & Aims: It is believed that uterine septum, because of its effect on infertility and recurrent abortion is very important and pregnancy outcome is obviously improved by hysteroscopic metroplasty (HM). In this study, the probable relationship of uterine septum dimensions (length and width) with infertility and recurrent abortion has been investigated. Methods: This clinical trial was carried out from Jan. 2004 to Feb. 2007 on all patients referred to Ahwaz educational hospitals for evaluation of infertility and recurrent abortion and underwent hysterosalpingography (HSG). Patients with suspected uterine septum were referred to Imam Khomeyni Hospital and underwent simultaneous hysteroscopy and laparoscopy. After that hysteroscopic metroplasy was done. The participants were checked by new HSG after one month and were evaluated for pregnancy outcome after one year. Results: In whole, 50 patients (28 cases with infertility and 22 cases with recurrent abortion) were studied. In 62.5% septum width was equal or less than 3cm and in 48% length of septum occupied two thirds of uterine cavity and there was no significant difference between the tow groups in regard to septum's width and length. Rate of pregnancy occurrence was 71.4% in patients with infertility and 76.5% in patients with recurrent abortion and no significant difference was found between the two groups in this regard. Conclusion: According to the findings, it seems that septum dimensions (width and length) have no role in infertility and abortion. Therefore, resection of uterine septum regardless of its size is recommended. In patients with uterine septum who suffer from infertility and recurrent abortion, HM is an appropriate approach. Keywords: Infertility, Hysteroscopy, Recurrent abortion, Septate uteru