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Productivity of an orchard generally depends upon the fertility of the soil and the nutrient requirements of the fruit trees. Phosphorus (P) extractability from soils influences the P sorption, release patterns, and P bioavailability. A study was carried out to investigate P extractability via seven extraction methods in relation to soil properties in three fruit orchards. In total, 10 soil samples were collected from each fruit orchard, namely, citrus (Citrus sinensis L.), loquat (Eriobotrya japonica L.), and guava (Psidium guajava L.), located in similar ecological conditions to the Haripur district of Pakistan. Available P in the soil was extracted using deionized H2O, CaCl2, Mehlich 1, Bray 1, Olsen, HCl, and DTPA methods. Selected soil properties [pH, electrical conductivity (EC), soil organic matter (SOM)], texture, cation exchange capacity (CEC), macronutrients, and micronutrients were also determined. Soils sampled from orchards indicated significant differences in soil properties. Orchards have sequestered more amount of C stock in soil than without an orchard. The extractability of P from soils was profoundly affected by P extraction methods. The average amount of extractable P was relatively higher in those soils where the total amount of P was also higher. These methods extracted different pools of soil P with varying P concentrations regulated by the soil properties. Phosphorus amounts extracted were varied in the order of HCl > DTPA > Mehlich 1 > Bray 1 > Olsen > CaCl2 > water. Among orchards, a higher amount of P was found in soils of loquat followed by citrus and guava orchards. Regardless of the method, subsurface soil got a lower concentration of extractable P than surface soil in all orchards. The extractable P was highly associated with soil properties. DTPA extractable P was related to SOM soil clay content and CEC by R2 values of 0.83, 0.87, and 0.78, respectively. Most of the extraction methods were positively correlated with each other. This study indicated that SOM inputs and turnover associated with orchard trees exhibited a substantial quantity of extractable P in soils. Predicting available P in relation to its bioavailability using these methods in contrasting soils is required.

Severe to extreme sour-corrosive environment assisted cracking (EAC) phenomenon are complex. Mandatory test qualification requirements and acceptance criteria is non-existent, in relevant API and NACE standards for fracture toughness of the CRA's. This paper, perhaps an industry first, attempts to highlight some of these gaps and how it translates into material strength uncertainties thereby impacting tubing design and risk assessment. The materials in this context are high strength group 1 to 4 corrosion resistant alloys of API 5CRA. Fracture toughness or critical stress intensity factor is a measure of resistance to failure due to crack propagation - a key parameter for HPHT tubing material selection and design. This material aspect of fracture toughness can be influenced by several factors like Microstructure, Strength, Hardness, Heat treatment, Anisotropy etc. Low temperature is generally considered as worst case, nevertheless at higher temperatures, well environment driven embrittlement can have a serious impact on the fracture toughness value. Therefore, with several factors influencing, its characterization is important to define the burst envelope of the tubing when exposed to severe to extreme sour-sweet corrosive environment typical of HPHT wells. A unique approach is followed to determine the brittle burst tri-axial envelope of selected tubing based on minimum fracture toughness value of the CRA material, referred to as KIMAT for SSC (or EAC) as prescribed by the mill. Proportional radial scaling is proposed to generate scaled down von-mises brittle-burst envelope. The tubing loads and the safety factors are analyzed to the shrunken envelope to visualize the risks of tubular failure under sour-sweet corrosive environment. The analysis includes varying crack depths of 5% and 3%. In addition, a minimum KIMAT for SSC (or EAC) value required to achieve full scale VME is investigated to determine specific material property requirements. TM0177 NACE D covers methods to measure fracture toughness KIMAT for sour service at ambient temperature only and does not address the context of EAC exposure at ambient or elevated conditions i.e., KIMAT for EAC.This implies that a methodology for evaluation of EAC risk is not available as yet. Guidance on the potential for corrosion to cause cracking of CRAs is given in Table B.1 of ISO 15156-3 with primary and secondary failure mechanisms. However, a quantitative test to cover the risk of cracking of materials by specifying minimum required KIMAT for EAC for each group type in 5CRA is non-existent. Even KIMAT for sour service minimum requirements with SSC as primary failure mechanism, e.g., group 1 CRA, does not currently exist. Consequently, KIMAT for EAC minimum requirements are considered as far-fetched. Additionally, mills prescribed KIMAT for SSC lacks basis due to gaps in the minimum fracture toughness requirement stipulations for group 1 to 4 CRA materials listed at API 5CRA. Therefore, this paper provides risk insights and potential of tubing failure that can lead to serious integrity issues on a HPHT well. A joint industry program or joint API/NACE task group is proposed as a logical next step.

HPHT well environments present design & operational challenges that could potentially translate into well failure with high consequences. Several risk elements can combine into a complex hazard causing serious threat to well design & integrity. Risk elements could be complex downhole environment, material deration, material incompatibility with the completion/packer fluids and other treatment fluids, metallurgy imbalances etc. This case study presents early life production tubing integrity failure highlighting gaps and suggestions to adopt an integrated risk mitigation approach. A 5,700 m TVD keeper HPHT exploratory well was drilled in north of Pakistan with reservoir pressure, temperature exceeding 10,000 psi and 320°F respectively. Matrix acidizing was required to remove near wellbore damage in the targeted carbonate reservoir. Initial kick start stimulation efforts resulted in tubing-annulus communication indicating compromised CRA super 13CR completion string integrity. Workover followed wherein another early life completion string failure occurred. Consequently, comprehensive analysis was carried out to determine failure root causes using a systematic fault tree analysis approach. Failure investigation consisted of two broad scopes: a) Scrutinize well design against established industry standards and best practices for HPHT wells and; b) Completion string material metallurgy tests to evaluate compatibilities with exposed well & treatment fluids, bottom hole environment and assessment of all possible risk scenarios that by itself or in combination with other risks could cause material failure. Further, detailed study work included describing bottom hole environment comprehensively, various types of corrosion risk assessments including evaluation of environment assisted cracking risks, acid inhibitor efficiency evaluation, completion/packer fluid selection, fluid compatibility assessment and fluid additives degradation at high temperatures. Mill manufacturing processes, susceptibility of CRA material passive layer because of austenite percentage were also looked-into. Based on systematic approach and extensive in-depth analysis, key observations were drawn. These observations were further investigated with material testing and possible root cause failure risk factors were arrived at. Conclusions were drawn highlighting primary and secondary failure root causes. A new basis of design and qualification protocols was proposed to mitigate various risks to ALARP. Holistic HPHT well design approach is found to be lacking pan industry as the complex failures risk mitigation information is either not available or is discrete. Operators venturing into HPHT for the first time are challenged to comprehend requisite steps required to mitigate the risks to ALARP. Therefore, the paper aims to provide an integrated approach for completion metallurgy selection and test qualification requirements for stimulation and completion fluid in conjunction with the downhole environment.

With the continuous increase in global energy demands, it has become imperative to get the most out of the existing reserves in developed fields. While focusing on maximizing productivity, the conventional methods of well completions are not always optimal. Cemented Liner Completions in multi-layered reservoirs can at times be in-efficient and thereby create issues of zonal isolation and well integrity, besides causing irreversible damage to reservoir sections. To overcome these obstacles, and to provide an added advantage of selective stimulation in multiple zones, industry is gradually moving towards open-hole multi Stage Frac Completions. This paper presents an operational overview of first ever deployment of an open-hole completion in a mature gas condensate field located in Potohar region in Pakistan. It had been a norm in this field to hydraulically fracture the two producing zones after cementing the liner. However, often the fold of increase was very marginal despite establishing the hydraulic fracturing design patterns for this field with confidence. In addition, these stimulating operations were frequently compromised because of well and completion design constraints. Execution of open hole completion resulted in gains in the operational efficiency, improved well productivity and had cost benefits which are analyzed against offset wells completed as cased-hole. One interesting observation made is the comparison of un-stimulated base case for the well under discussion against various offset wells located in the field that were hydraulically fractured and how it outshines them with respect to the net production gains. This can be attributed to the characteristic of open-hole completions that provides maximum reservoir contact with minimal formation damage. Based on this experience, it is recommended on integrating and experimenting with relatively new, yet industry established, ideas into field development plans for mature fields with respect to completion design. This can have a lasting impact in extending the plateau production region of the field.

The case study presents an integrated workflow with the focus on the thermal analysis of the completion string, wellhead and surface network. The research outcome are the temperature profiles under various production scenarios that are used as the justification of the installation of wellhead cooler on an exploratory well of lower Indus basin in Pakistan. The advent of deep well drilling in high temperature and high pressure formations posed serious concerns for drilling, completion and facility design engineers as these are one of the key parameters for material and fluid selection for completion string. The uncertainty in these parameters throughout the operational life of the well may cause an over-designed or underdesigned well completion and production facility. The equation gets further complex if the inherent uncertainty in type and quantity of produced fluids is neglected or underestimated. To overcome these challenges, a workflow considering the downhole completion considerations and wellhead treatment of produced fluid; in consideration of wellhead temperature; is proposed. This paper presents reservoir and completion design considerations of an exploratory well in lower indus basin. Effect of various production scenarios on temperature profile are considered based on the possible drive mechanisms of hydrocarbon production. The analysis includes the development of completion string model for well S-X1 and coupling the same with the hydrocarbon processing facility through surface network. The model is calibrated using history matching of temperature profile using the production data and sensitivity analysis of various parameters was performed. Based on the simulation results, it was observed that the proposed workflow using industry standard commercial software for thermal analysis is a more realistic approach for temperature prediction using production profiles. The proposed workflow will serve as the guidelines for wellhead and surface facility design under various expected production scenarios.

This study analyzes the impact of globalization on unemployment in Pakistan, using annual data for the period 1980 to 2013. Using the ARDL econometric framework, we find that the economic, political and social aspects of globalisation differ in their effects. The data suggest that political and social integration, whilst beneficial in the short run, increase the long run expected unemployment rate. Economic integration appears to be only marginally beneficial in the short run; it is significantly beneficial in the long run but cointegration with the other aspects of globalisation means that it cannot fully counteract their undesirable long-run effect.

The basic idea behind this research is to propose a work flow to model gas flow in numerical simulators, which would take into consideration all the complexities of the multiple porosity systems that exist in shale matrix and the different dynamics of flow involved within them. The concept of a multi porosity system that is composed of the organic part (kerogen), inorganic matter and natural and hydraulic fractures is used here. Kerogen is very different from other shale components because of its highly porous nature, capability to adsorb gas and abundance of nano-pores on its surface. Some theories had been forwarded for the physics involved with gas flow in shale on a micro scale level. However, when working with reservoir scale models, the details as described for porosity systems in micro scale models is lost. To overcome this problem, the idea of dynamic apparent permeability, which is a function of matrix pressure, is introduced in this work. It helps in up-scaling the particulars of the micro scale model to a reservoir one and aids in modelling Darcy flow, Fickian diffusion and transition flow in between the matrix and fractures. Our assumptions are validated by working with the case of a multi-stage hydraulically fractured horizontal gas well producing from the Barnett shale formation. Exisiting simulation model for this well doesn't take into consideration the relevant flow phenomenon and is used as a base case. History matching after integrating diffusion and desorption, with 7 years of production data, into model reveals that considering these additional processes impacts the assumed SRV region - affecting its volume as well as its properties. This is a critical factor in optimizing completion design, to lower down the well cost for same or even greater production. We summarize our findings from production forecasts that matrix contribution towards production is under estimated when relevant assumptions for shale are not modelled. This signifies the importance of better understating the transport phenomenon occurring in shale, which would enable us to have a greater insight to scrutinize production data and later to predict changes in production as completion methods are changed. Similarly, this can play a vital role in well spacing for effective field development. This means that a multi stage high density fracturing job might not optimize the well in terms of its value. Decreasing our expenditure on well completions, such that their design results in lower production rates at the initial time period along with lower decline rates, would enable us to produce these wells longer for the same recovery. This would enable us to push the production in future where oil and gas prices might be better.

This study investigates the effect of block ownership (institutions and state) on CEO compensation and the extent to which gender diversity in the corporate board moderates this nexus during the period from 2008 to 2016 in all Chinese A-share listed firms. The empirical findings of our study are twofold. First, our results indicate that institutional ownership has a positive and significant impact on CEO compensation, while state ownership has a negative and significant impact on CEO compensation. Second, by analysing the moderating role of gender diversity, our results show that gender diversity negatively (positively) moderates the relationship between institutional (state) ownership and CEO compensation. These findings are robust with the use of an alternative measure of CEO compensation and estimation techniques. Overall, our study supports the resource dependence perspective of the moderating role of board gender diversity. Refereed/Peer-reviewed

Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy. DNA from these patients was subjected to whole exome sequencing. In all patients, compound heterozygous variants in a new disease gene, LIG3, were identified. All variants were predicted to have a damaging effect on the protein. The LIG3 gene encodes the only mitochondrial DNA (mtDNA) ligase and therefore plays a pivotal role in mtDNA repair and replication. In vitro assays in patient-derived cells showed a decrease in LIG3 protein levels and ligase activity. We demonstrated that the LIG3 gene defects affect mtDNA maintenance, leading to mtDNA depletion without the accumulation of multiple deletions as observed in other mitochondrial disorders. This mitochondrial dysfunction is likely to cause the phenotypes observed in these patients. The most prominent and consistent clinical signs were severe gut dysmotility and neurological abnormalities, including leukoencephalopathy, epilepsy, migraine, stroke-like episodes, and neurogenic bladder. A decrease in the number of myenteric neurons, and increased fibrosis and elastin levels were the most prominent changes in the gut. Cytochrome c oxidase (COX) deficient fibres in skeletal muscle were also observed. Disruption of lig3 in zebrafish reproduced the brain alterations and impaired gut transit in vivo. In conclusion, we identified variants in the LIG3 gene that result in a mitochondrial disease characterized by predominant gut dysmotility, encephalopathy, and neuromuscular abnormalities. Bonora et al. identify a new mitochondrial recessive disorder caused by biallelic variants in the LIG3 gene encoding DNA ligase III, which is responsible for mitochondrial DNA repair. Clinical signs include gut dysmotility and neurological features such as leucoencephalopathy, epilepsy and stroke-like episodes.

Inherited optic neuropathies include complex phenotypes, mostly driven by mitochondrial dysfunction. We report an optic atrophy spectrum disorder, including retinal macular dystrophy and kidney insufficiency leading to transplantation, associated with mitochondrial DNA (mtDNA) depletion without accumulation of multiple deletions. By whole-exome sequencing, we identified mutations affecting the mitochondrial single-strand binding protein (SSBP1) in 4 families with dominant and 1 with recessive inheritance. We show that SSBP1 mutations in patient-derived fibroblasts variably affect the amount of SSBP1 protein and alter multimer formation, but not the binding to ssDNA. SSBP1 mutations impaired mtDNA, nucleoids, and 7S-DNA amounts as well as mtDNA replication, affecting replisome machinery. The variable mtDNA depletion in cells was reflected in severity of mitochondrial dysfunction, including respiratory efficiency, OXPHOS subunits, and complex amount and assembly. mtDNA depletion and cytochrome c oxidase-negative cells were found ex vivo in biopsies of affected tissues, such as kidney and skeletal muscle. Reduced efficiency of mtDNA replication was also reproduced in vitro, confirming the pathogenic mechanism. Furthermore, ssbp1 suppression in zebrafish induced signs of nephropathy and reduced optic nerve size, the latter phenotype complemented by WT mRNA but not by SSBP1 mutant transcripts. This previously unrecognized disease of mtDNA maintenance implicates SSBP1 mutations as a cause of human pathology.