Wettability and Prediction of Oil Recovery From Reservoirs Developed With Modern Drilling and Completion Fluids

Exposure to crude oil in the presence of an initial brine saturation can render rocks mixed-wet. Subsequent exposure to components of synthetic oil-based drilling fluids can alter the wetting toward less water-wet or more oil-wet conditions. Mixing of the non-aromatic base oils used in synthetic oil-based muds (SBM) with an asphaltic crude oil can destabilize asphaltenes and make cores less water-wet. Wetting changes can also occur due to contact with the surfactants used in SBM formulations to emulsify water and make the rock cuttings oil-wet. Reservoir cores drilled with SBMs, therefore, show wetting properties much different from the reservoir wetting conditions, invalidating laboratory core analysis using SBM contaminated cores. Core cleaning is required in order to remove all the drilling mud contaminants. In theory, core wettability can then be restored to reservoir wetting conditions by exposure to brine and crude oil. The efficiency of core cleaning of SBM contaminated cores has been explored in this study. A new core cleaning procedure was developed aimed to remove the adsorbed asphaltenes and emulsifiers from the contaminated Berea sandstone cores. Sodium hydroxide was introduced into the cleaning process in order to create a strongly alkaline condition. The high pH environment in the pore spaces changed the electrical charges of both basic and acidic functional groups, reducing the attractive interactions between adsorbing materials and the rock surface. In cores, flow-through and extraction methods were investigated. The effectiveness of the cleaning procedure was assessed by spontaneous imbibition tests and Amott wettability measurements. Test results indicating that introduction of sodium hydroxide played a key role in removing adsorbed materials were confirmed by contact angle measurements on similarly treated mica surfaces. Cleaning of the contaminated cores reversed their wettability from oil-wet to strongly water-wet as demonstrated by spontaneous imbibition rates and Amott wettability indices

Recruiting and consenting into a peripartum trial in an emergency setting: a qualitative study of the experiences and views of women and healthcare professionals.

BACKGROUND: Recruiting and consenting women to peripartum trials can be challenging as the women concerned may be anxious, in pain, and exhausted; there may also be limited time for discussion and decision-making to occur. To address these potential difficulties, we undertook a qualitative evaluation of the internal pilot of a trial (Got-it) involving women who had a retained placenta (RP). We explored the experiences and views of women and staff about the information and consent pathway used within the pilot, in order to provide recommendations for use in future peripartum trials involving recruitment in emergency situations. METHODS: In-depth interviews were undertaken with staff (n = 27) and participating women (n = 22). Interviews were analysed thematically. The accounts of women and staff were compared to identify differences and similarities in their views about recruitment and consent procedures. RESULTS: Women and staff regarded recruitment as having been straightforward and facilitated by the use of simplified (verbal and written) summaries of trial information. Both parties, however, conveyed discordant views about whether fully informed consent had been obtained. These differences in perspectives appeared to arise from the different factors and considerations impinging on women and staff at the time of recruitment. While staff placed emphasis on promoting understanding in the emergency situation of RP by imparting information in clear and succinct ways, women highlighted the experiential realities of their pre- and post-birthing situations, and how these had led to quick decisions being made without full engagement with the potential risks of trial participation. To facilitate informed consent, women suggested that trial information should be given during the antenatal period, and, in doing so, articulated a rights-based discourse. Staff, however, voiced opposition to this approach by emphasising a duty of care to all pregnant women, and raising concerns about causing undue distress to the majority of individuals who would not subsequently develop a RP. CONCLUSIONS: By drawing upon the perspectives of women and staff involved in the same trial we have shown that they may operate within different experiential and ethical paradigms. In doing so, we argue for the potential benefits of drawing upon multiple perspectives when developing information and consent pathways used in future (peripartum) trials. TRIAL REGISTRATION: ISCRTN 88609453

Improved Water Flooding through Injection Brine Modification

Crude oil/brine/rock interactions can lead to large variations in the displacement efficiency of waterflooding, by far the most widely applied method of improved oil recovery. Laboratory waterflood tests show that injection of dilute brine can increase oil recovery. Numerous fields in the Powder River basin have been waterflooded using low salinity brine (about 500 ppm) from the Madison limestone or Fox Hills sandstone. Although many uncertainties arise in the interpretation and comparison of field production data, injection of low salinity brine appears to give higher recovery compared to brine of moderate salinity (about 7,000 ppm). Laboratory studies of the effect of brine composition on oil recovery cover a wide range of rock types and crude oils. Oil recovery increases using low salinity brine as the injection water ranged from a low of no notable increase to as much as 37.0% depending on the system being studied. Recovery increases using low salinity brine after establishing residual oil saturation (tertiary mode) ranged from no significant increase to 6.0%. Tests with two sets of reservoir cores and crude oil indicated slight improvement in recovery for low salinity brine. Crude oil type and rock type (particularly the presence and distribution of kaolinite) both play a dominant role in the effect that brine composition has on waterflood oil recovery

Changing antiepilepsy drug-prescribing trends in women with epilepsy in the UK and Ireland and the impact on major congenital malformations

Objectives: After 20 years of data collection, pregnancy registers have informed prescribing practice. Various populations show trends for a reduction in valproate prescribing, which is associated with an increased risk of anatomical teratogenesis and neurodevelopmental effects in those exposed in utero. Our aim was to determine if any shifts in prescribing trends have occurred in the UK and Ireland Epilepsy and Pregnancy Register cohort and to assess if there had been any change in the overall major congenital malformation (MCM) rate over time. Methods: The UK and Ireland Epilepsy and Pregnancy Register, a prospective, observational, registration and follow-up study established in 1996, was used to determine the changes in antiepileptic drugs (AEDs) utilised during pregnancy and the MCM rate between 1996 and 2016. Linear regression analysis was used to assess changes in AED utilisation, and Poisson regression was used for the analysis of trends in the MCM rates. Results: Outcome data for 9247 pregnancies showed a stable percentage of monotherapy to polytherapy prescribing habits over time. After Bonferroni correction, statistically significant (p<0.003) changes were found in monotherapy prescribing with increases in lamotrigine and levetiracetam and decreases in valproate and carbamazepine use. Between 1996 and 2016, the total MCM rate showed a 2.1% reduction per year (incidence risk ratio 0.979 (95% CIs 0.956 to 1.002) but Poisson regression analysis showed that this was not statistically significant p=0.08). Conclusion: Significant changes are seen in the prescribing habits in this cohort over 20 years, but a statistically significant change in the MCM rate was not detected. This work should be replicated on a larger scale to determine if significant changes are occurring in the MCM rate, which would allow a robust economic estimate of the benefits of improvements in prescribing practice and the personal effect of such changes

A pragmatic group sequential placebo controlled randomised trial to determine the effectiveness of Glyceryl trinitrate for retained placenta (GOT-IT): a study protocol

A retained placenta is diagnosed when the placenta is not delivered following delivery of the baby. It is a major cause of postpartum haemorrhage and treated by the operative procedure of manual removal of placenta (MROP).The aim of this pragmatic, randomised, placebo-controlled, double-blind UK-wide trial, with an internal pilot and nested qualitative research to adjust strategies to refine delivery of the main trial, is to determine whether sublingual glyceryl trinitrate (GTN) is (or is not) clinically and cost-effective for (medical) management of retained placenta. The primary clinical outcome is need for MROP, defined as the placenta remaining undelivered 15 min poststudy treatment and/or being required within 15 min of treatment due to safety concerns. The primary safety outcome is measured blood loss between administration of treatment and transfer to the postnatal ward or other clinical area. The primary patient-sided outcome is satisfaction with treatment and a side effect profile. The primary economic outcome is net incremental costs (or cost savings) to the National Health Service of using GTN versus standard practice. Secondary outcomes are being measured over a range of clinical and economic domains. The primary outcomes will be analysed using linear models appropriate to the distribution of each outcome. Health service costs will be compared with multiple trial outcomes in a cost-consequence analysis of GTN versus standard practice.Ethical approval has been obtained from the North-East Newcastle and North Tyneside 2 Research Ethics Committee (13/NE/0339). Dissemination plans for the trial include the Health Technology Assessment Monograph, presentation at international scientific meetings and publication in high-impact, peer-reviewed journals.ISCRTN88609453; Pre-results

Fundamentals of reservoir surface energy as related to surface properties, wettability, capillary action, and oil recovery from fractured reservoirs by spontaneous imbibition

The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the non-wetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face

Effects of dopamine D1 modulation of the anterior cingulate cortex in a fear conditioning procedure

The anterior cingulate cortex (AC) component of the medial prefrontal cortex (mPFC) has been implicated in attention and working memory as measured by trace conditioning. Since dopamine (DA) is a key modulator of mPFC function, the present study evaluated the role of DA receptor agents in rat AC, using trace fear conditioning. A conditioned stimulus (CS, noise) was followed by an unconditioned stimulus (US, shock) with or without a 10s trace interval interposed between these events in a between-subjects design. Conditioned suppression of drinking was assessed in response to presentation of the CS or an experimental background stimulus (flashing lights, previously presented for the duration of the conditioning session). The selective D1 agonist SKF81297 (0.05 µg/side) or D1 antagonist SCH23390 (0.5 µg/side) was administered by intra-cerebral microinfusion directly into AC. It was predicted that either of these manipulations should be sufficient to impair trace (but not delay) conditioning. Counter to expectation, there was no effect of DA D1 modulation on trace conditioning as measured by suppression to the noise CS. However, rats infused with SKF81297 acquired stronger conditioned suppression to the experimental background stimulus than those infused with SCH23390 or saline. Thus, the DA D1 agonist SKF81297 increased conditioned suppression to the contextual background light stimulus but was otherwise without effect on fear conditioning

Lead exposure in adult males in urban Transvaal Province, South Africa during the apartheid era

Human exposure to lead is a substantial public health hazard worldwide and is particularly problematic in the Republic of South Africa given the country’s late cessation of leaded petrol. Lead exposure is associated with a number of serious health issues and diseases including developmental and cognitive deficiency, hypertension and heart disease. Understanding the distribution of lifetime lead burden within a given population is critical for reducing exposure rates. Femoral bone from 101 deceased adult males living in urban Transvaal Province (now Gauteng Province), South Africa between 1960 and 1998 were analyzed for lead concentration by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Of the 72 black and 29 white individuals sampled, chronic lead exposure was apparent in nearly all individuals. White males showed significantly higher median bone lead concentration (ME = 10.04 µg·g−1), than black males (ME = 3.80 µg·g−1) despite higher socioeconomic status. Bone lead concentration covaries significantly, though weakly, with individual age. There was no significant temporal trend in bone lead concentration. These results indicate that long-term low to moderate lead exposure is the historical norm among South African males. Unexpectedly, this research indicates that white males in the sample population were more highly exposed to lead