BI-OPTIMIZATION OF DURABILITY AND RHEOLOGICAL PERFORMANCE OF OIL WELL CEMENT SLURRY USING LOCALLY SOURCED EXTENDER

Bentonite used during drilling and cementing operations in Nigeria are imported into the country despite the availability of this raw material, which will increase the Gross Domestic Products (GDP) of this country if properly processed and utilized instead of imported bentonite. This investigation evaluated the performance of three selected Nigerian bentonites sourced from the South-Western part of Nigeria for oil well-cementing operation. The raw and beneficiated samples from each location were prepared and characterized using X-ray Fluorescence (IVT-20 XRF) to determine the elemental composition of each sample pre and post beneficiation. The beneficiated sample with properties close to that of Wyoming bentonite was chosen for the oil well cement slurry analysis. The measured parameters used in the analysis of the suitability of local samples used in oil well-cementing operation were compressive strength and rheological properties. Box-Behnken Design (BBD) was used for the study of the optimum quantity of bentonite required for cementing specification and bi-optimization values for both the comprehensive and rheological properties. The results of this investigation showed that all local clay samples in raw form failed the specification of the American Petroleum Institute (API). After beneficiation, Ibeshe Bentonite (IB) had the highest sodium content and the ratio of the exchangeable cations, 190% increment in sodium-ion was recorded in IB after beneficiation and the slurry yield of IB (2.7 ft3 per sack) was greater than that of  Wyoming Bentonite 1.9 ft3 per sack) when both are subjected to the same experimental condition. Bi-optimization models predicted optimum experimental conditions with an accuracy of between 0.35 and, 1.26 % for both comprehensive and rheological parameter

MODIFICATION OF NIGERIAN BENTONITE FOR UTILIZATION IN OIL WELL DRILLING OPERATIONS

More than 80 bentonite clay deposit sites had been identified in Nigeria. Yet, almost all clay and additives used for drilling oil well are imported. The reason is partly that in their natural states, they do not swell while polymers in their raw forms remain unstable at high temperatures. This study aimed at evaluating the potentials of chemically modified Nigerian bentonite for application in the oil and gas industry. The Gombe bentonite from Gombe State was beneficiated using NAHCO3 and slurries were made by dispersion in distilled water. In the presence of other local additives, evaluation of the slurries was carried out on the basis of filtration loss and rheology at different temperatures (30, 60 and 85 oC) using a Central Composite Design (CCD). The clay sample was characterized for mineral and elemental compositions using X-ray diffractometer (XRD) and X-ray fractometer (XRF) while proximate analysis was carried out on the additives. At the optimum condition, the result shows a significant improvement in mud rheology and fluid loss at various temperatures which are in close agreement with the API recommended standard

OPTIMIZATION OF PROCESS PARAMETERS FOR NATURAL GAS SWEETENING USING ASPEN HYSYS AND RESPONSE SURFACE METHODOLOGY

Amines process remains the most economic and efficient technology available today for the removal of acid gases. However, the costs associated with pumping higher flow rates and cost of increased energy needs for the regeneration of solution can undermine the economic feasibility of the project portfolio. The absorber pressure, the composition and temperature at which the sour gas is available dictates sour gas and amine flow rates needed to meet the sweet gas specifications. To improve absorber capacity for a given sweet gas specification, optimization are commonly carried out using spread sheet with an adjust function to manipulate sour gas flow rate for fixed amine flow rate. This study performed optimization using response surface methodology on a simulated and calibrated amine plant. The result shows that the optimum operating conditions for 96% CO2 removal were temperature of 30 oC, mass flow rate of 868.75 kg/hr and 20 numbers of plates. In conclusion, using experimental design and response surface methodology the parameter manipulation for attainment of optimal conditions is overcome

KVANTITATIVNA PROCJENA RIZIKA UTJECAJA PIJESKA NA VIŠEFAZNI PROTOK U CJEVOVODU

The presence of sand particles flowing along with reservoir fluids in a pipeline increases the probability of pipeline failure. The risk of pipeline failure is either accentuated or abated by the flow conditions of the fluids in the pipeline. In this study, a quantitative risk analysis of the effect of sand on pipelines during multiphase flow, under the pipeline failure modes; sanding up, erosion, and encountering abnormal pressure gradient was conducted. Three piping components were considered: line pipe (nominal size 1.5 in [3.8 cm]), swing check valve (nominal size 12.007 in [30.5cm]) and 90 deg LR Elbow (nominal size 2.25 in [5.7cm]). Correlations that indicate the critical velocities and the critical sand concentrations above/below which these failures occur were employed and implemented in a Visual Basic program. The analysis was conducted at a temperature of 204 °C and pressure of 604 psi [4.2×106 Pa]. A probability distribution, simulating real-life scenario was developed using Monte Carlo simulation. This determines the probability of deriving critical sand concentration values that fall beyond the set statistical limits which indicates the probability of occurrence of the failure being investigated. For all three failures, the severity of occurrence (represented by CAPEX incurred in solving the failures) was multiplied with the probability of failure which gave rise to the risk indexes. Based on the histogram plot of average risk index and analysis, the study reveals that larger diameter components are prone to turbulence which lead to greater risk of erosion. The risk of abnormal pressure drop and sanding up were considerably lower than that for erosion (abrasion).Prisutnost čestica pijeska, koje zajedno s proizvodnim fluidom protječu cjevovodom, povećava vjerojatnost nastanaka kvara na cjevovodu. Rizik od kvara na cjevovodu uvelike ovisi (ili je dodatno potenciran ili je smanjen) o uvjetima protjecanja fluida u cjevovodu. U ovome su radu prikazani rezultati kvantitativne analize rizika utjecaja pijeska na cjevovode tijekom višefaznoga protjecanja u uvjetima nastanka kvara na cjevovodu: nakupljanja pijeska, erozije i pojave povećanoga gradijenta tlaka. U analizi su razmatrane tri komponente cjevovoda: cijev (nominalna veličina 1,5 in [3,8 cm]), ventil s povratnom zaklopkom (engl. swing check valve) (nominalna veličina 12,007 in [30,5 cm]) i LR koljeno od 90 stupnjeva (nominalna veličina 2,25 in [5,7 cm]). Korelacije, koje upućuju na kritične brzine i kritične koncentracije pijeska vrijednosti iznad ili ispod kojih se navedeni kvarovi cjevovoda javljaju, prikazane su u programu Visual Basic. Analiza je provedena na temperaturi od 204 ˚C i tlaku od 604 psi [4,2 × 106 Pa]. Distribucija vjerojatnosti, simulirajući realan scenarij, dobivena je korištenjem Monte Carlo simulacije. Utvrđena je vjerojatnost pojave kritičnih vrijednosti koncentracije pijeska, koje se nalaze izvan postavljenih statističkih granica, što upućuje na vjerojatnost pojave uzroka kvara koji se istražuje. Za sva tri uzroka kvara posljedice pojave (prikazane kapitalnim troškovima (CAPEX) sanacije nastalih kvarova) pomnožene su s vjerojatnošću kvara, čime je dobiven indeks rizika. Na temelju histogramskoga dijagrama prosječnoga indeksa rizika i analize, provedenim istraživanjem utvrđeno je da su komponente većega promjera sklone turbulenciji, što dovodi do većega rizika od erozije. Rizik od velikoga pada tlaka i nakupljanja pijeska bio je znatno manji od rizika od erozije (abrazije)

Improving the Demulsification Process of Heavy Crude Oil Emulsion through Blending with Diluent

In crude oil production from brown fields or heavy oil, there is production of water in oil emulsions which can either be controlled or avoided. This emulsion resulted in an increase in viscosity which can seriously affect the production of oil from sand phase up to flow line. Failure to separate the oil and water mixture efficiently and effectively could result in problems such as overloading of surface separation equipments, increased cost of pumping wet crude, and corrosion problems. Light hydrocarbon diluent was added in varied proportions to three emulsion samples collected from three different oil fields in Niger delta, Nigeria, to enhance the demulsification of crude oil emulsion. The viscosity, total petroleum hydrocarbon, and quality of water were evaluated. The viscosity of the three emulsions considered reduced by 38, 31, and 18%. It is deduced that the increase in diluent blended with emulsion leads to a corresponding decrease in the value of viscosity. This in turn enhanced the rate of demulsification of the samples. The basic sediment and water (BS&W) of the top dry oil reduces the trace value the three samples evaluated, and with optimum value of diluent, TPH values show that the water droplets are safe for disposal and for other field uses