Showing papers by "Sonatrach published in 2018"

Experimental Investigation of Wettability Alteration of Oil-Wet Carbonates by a Non-ionic Surfactant

Abstract: Wettability alteration toward a more water-wet state was found to be a promising approach for oil recovery improvement in oil-wet and naturally fractured carbonate reservoirs. This approach has bee...

Application of Improved Artificial Neural Network Algorithm in Hydrocarbons’ Reservoir Evaluation

Abstract: The aim of this work is to develop an artificial neural network software tool in Matlab which allows the well logging interpreter to evaluate hydrocarbons reservoirs by classification of its existing facies into six types (clay, anhydrite, dolomite, limestone, sandstone and salt), the advantage of such classification is that it is automatic and gives more precision in comparison to manual recognition using industrial software. The developed algorithm is applied to eleven wells data of the Algerian Sahara where necessary curves (Gama Ray, density curve Rhob, Neutron porosity curve Nphi, Sonic curve dt, photoelectric factor curve PE) for realization of this technique are available. A graphical user interface is developed in order to simplify the use of the algorithm for interpreters.

Assessment of PIPE for CO 2 transportation using a constraint modified CTOD failure assessment diagram

Abstract: Failure Assessment Diagram (FAD) is constraint modified using the assumption that the constraint T stress is proportional to the non-dimensional loading. The constraint modified FAD has been used to compute safety factors associated elliptic defects.

Comparative study of the noise generated by the moto-compressor and that generated by the turbo-compressor

Abstract: The fundamental aim of this study is to compare between the noise generated by the moto-compressor and the noise generated by the turbo-compressor operating 24H/24H on the continuous function mode; these two machines make part of the equipment of the GP1Z, a factory of hydrocarbon treatment. To attain the principal objective of this study we divided our work into two parts, in the first part we followed and evaluated the average level of the noise emitted by the two machines, whereas in the second part we studied the noise propagation emitted by the two machines and its impact on the generation of the noise. The results obtained from this study demonstrate that the noise generated by the turbo-compressor is higher than the noise generated by the moto-compressor. Keywords : noise; moto-compressor; turbo-compressor; noise maping.

Inhibition of asphaltene flocculation in light crude oil: effect of pressure, temperature and inhibitor concentration

Abstract: In this study, a light crude oil sample was taken from Hassi Messaoud field to characterize its physicochemical properties. The asphaltene flocculation onset was determined in the dead oil by Flocc...

Hydrate Mitigation and Flare Reduction Using Intermittent Gas Lift in Hassi Messaoud, Algeria

Abstract: Hassi Messaoud (HMD) is a mature oil field with approximately 1100 production wells. About half of the wells are natural flow and the other half are continuously gas lifted (CGL) with concentric (CCE) strings. CCE gas lift is different from conventional gas lift as the lift gas is injected in the well through the CCE string while production is from the annulus between the CCE string and the tubing. The typical production tubing size is 4 ½". The sizes of the CCE strings include 1.315", 1.66", and 1.9". The 1.66" CCE is most commonly used in gas lift wells. The typical gas lift injection line on the surface is 2" from the gas network to the wellhead. A choke is used on the gas lift line to control the lift gas injected into each well. As the injection gas pressure is high from the source of available lift gas, large pressure drops across the lift gas injection chokes exist in some wells. Due to the Joule-Thompson effects, a big temperature drop is associated with the large pressure drop across the lift gas injection choke. This temperature drop can result in hydrate formation in the lift gas line downstream of the gas lift choke. Hydrate formation in the gas injection lines, especially in winter has seriously disrupted production due to plugging of lift gas lines. Salt deposition is a big challenge in Hassi Messaoud field operation. The reservoir interstitial water contains high salt concentration in excess of 300 g/l. During well production, salt deposits in the wellbore and across the production choke. Periodically, water is required to be injected into the well to dissolve the salt and restore well productivity. A CCE string allows water to be injected into the wellbore either concurrently with injection lift gas or separately by itself for a specific period of time. High volumes of lift gas are injected in many wells due to the lack of effective control in the lift gas injection rates. The excessive gas from lift gas injection and production in the system can lead to the need to flare occasionally when the facility gas capacity limit is exceeded. In order to reduce the usage of the high volume of lift gas, Intermittent Gas Lift (IGL) was selected in a pilot project to evaluate its applicability in the Hassi Messaoud field. Three CGL wells were selected for this pilot project. The selected wells are characterized by high GOR, low PI and without continuous concurrent water injection (with lift gas) to dissolve salt deposited down-hole. IGL operation parameters were designed by using modified empirical correlations to those presented in the API Recommended Practice for Intermittent Gas Lift. The modifications were suited for the operating conditions in Hassi Messaoud Field. Static and dynamic well and network models were created to simulate the field test results and guide new designs and future applications. This paper presents the pilot test programs and the results from this project in mitigating both the excessive lift gas injection problem and injection line blockage due to hydrate by converting certain CGL wells to IGL. It also highlights the application conditions for the future. Finally, the plan for the expanded application of IGL in Hassi Messaoud is discussed.

Corrosion defect harmfulness by domain failure assessment diagram

Abstract: WE ARE REPORTING in this study the detection of 1888 corrosion defects using a magnetic pig over 70 km of a pipeline located in Algeria. This large amount of defects has been statistically analysed. The relative defect depth a/t exhibited a large scatter and no correlation was found between corrosion defect depth and length. For the necessity of repairing defect, two tools are available: the first is based on limit analysis and called the estimated repair factor (ERF) while the second is based on the failure assessment diagram. The adopted tool in the current study was the domain failure assessment diagram (DFAD). Analysis made with FAD concerns 66.8% of corrosion defects, with a limit analysis (LA) of 32.5%.After categorizing the corrosion defect according to the used analysis tool, the safety factor or probability of failure of each assessment point was determined and compared to the repairing criteria. It appears that the ERF criterion is more conservative in our case than the probabilistic criterion as a probability of failure of 10-4 or a non-dimensional crack driving force equal to mean minus three standard deviations.

Experimental investigations of SDS adsorption on the Algerian rock reservoir: chemical enhanced oil recovery case

Abstract: The adsorption of surfactant on reservoir rocks or sands is one of the main factors that can significantly reduce the effectiveness of surfactant flooding for light oil recovery. The present work consists of study of the interaction between the surfactant sodium dodecyl sulfate (SDS) and the characteristics of Hassi Messaoud rock established using scanning electron microscopy, Fourier transform infrared analysis, Brunauer–Emmett–Teller surface area analysis and optical microscopy. Parametric study of the adsorption tests was carried out at a temperature between 25 and 80 °C. The conductivity method was used to measure the critical micellar concentration of the SDS surfactant in aqueous solutions. The adsorption data were adjusted using five isotherms and two kinetics of the anionic surfactant. The equilibrium conditions for crushed rock samples were obtained after 11 h of adsorption. According to the experimental results, the equilibrium data were well fitted by the Langmuir isotherm for sandstone sample at all temperatures. The pseudo-second-order model best describes the kinetics of the adsorption process. Furthermore, the adsorption process is exothermic. Several statistical error analyses were applied to evaluate the performance and accuracy of the proposed experiment. A systematic investigation is very useful for selecting an appropriate surfactant for enhanced oil recovery application and reservoir stimulation in the petroleum industry.

Assessment of a cracked pipe subject to transient flow by the Monte Carlo method

Abstract: THE PURPOSE OF THIS WORK is to assess the risk of failure of cracked pipe due to fluid transient. A mathematical model has been established based on the mass and momentum conservation laws, the system of hyperbolic partial differential equations has been solved by the method of characteristics and a finite difference method to calculate the maximum pressure in the pipe. Afterwards, a finite element method have been used to perform a reliable assessment analysis of a cracked pipe used in water distribution by using Monte Carlo method and failure assessment diagram (FAD) tools to evaluate the safety factor from deterministic and probabilistic view points.

Analysis of the cement clinker produced with incorporation of petroleum sludge

Abstract: Very limited researches have been conducted on the incorporation of petroleum sludge waste into cement clinker production even though this waste may contain similar components to those of clinker raw materials. In this research, petroleum sludge was integrated into cement plant as raw material to produce the cement clinker. As results, incorporation of 5% of this waste was able to produce an acceptable quality of cement. Despite the use of petroleum sludge has decreased the properties of the produced clinker, but it still fit the requirements.

A Fourier-Transform Infrared (FTIR) study for Algerian asphaltenes

Abstract: despite that the Algerian light oil contain a few quantity of asphaltenes (under to 0.7 wt %)but The problem of their deposition during the oil production and transportation is strongly suggested, this deposition of asphaltenes does not depend on the percentage of asphaltenes in the oil but depends on their chemical composition which affects the behavior of asphaltenes. Functional Groups of Algerian Asphaltenes was investigated using A Fourier-Transform Infrared (FTIR),This study characterizes a Six samples of asphaltenes were collected from Hassi Messaoud’s oil field at different locations, all samples were extracted using n-heptene with with 1:40 (g/ml) (oil to solvent ratio),the obtained results indicated the existence of aliphatic, aromatic and sulfoxide groups with different intensities. This study confirmed that the asphaltenes precipitation was occurs in all Hassi Messaoud’s oil field locations. Keywords : Asphaltenes; Extraction; Characterization; A Fourier-TransformInfrared (FTIR); Algerian Light oil.

Lessons Learned From Electrical Submersible Pumps Installed in High-Salinity and Corrosive Reservoir, TAGI Formation

Abstract: An experience of electrical-submersible-pump (ESP) -issues troubleshooting to overcome the high-corrosion media of GSA wells is presented. Additionally, actions taken to extend the run life of pumps are explained. GSA is the company in Algeria that adopted the ESP system including all services; therefore, there was no chance to share experience with other entities in the country. Thus, it became necessary to try all available approaches during a period of 10 years to mitigate ESP failures and, eventually, production downtime. To overcome the high salinity of >320 g/L, several actions were introduced by either of two ways—ESP equipment or well completion. Simple motors and protectors were changed to tandem to prevent water penetration inside the motor. Power cable was changed from galvanized to Monel armor for high resistance to corrosion. For well completion, single or double ½-in. water-dilution lines were adopted and were run along tubing and connected to tail pipe, which runs to perforations. Modification in completion metallurgy also took place, when carbon steel was replaced by Super 13Cr. Supplementary actions were taken at the surface; the pressure switch was connected with a variable-speed drive (VSD) to smoothly shut down the ESP for unforeseen surface-controlled subsurface-safety-valve (SCSSV) closures. The adopted actions yielded considerable positive results. ESP failures that originated from the motor were reduced from four per year during 2012 to only one failure in 2016. However, salt-deposition blocs were almost prevented, and resulted in decrement in bullheading and coiled-tubing interventions by 85%, except for some wells when salt-bloc buildup was occasionally quicker and more important than water-dilution rate. Running a ½-in. injection line along with the tail pipe lowered ESP-shutdown frequency. Also, changing the power-cable type gave roughly good results. After running Monel armor, the number of related power-cable failures decreased, contributing to the reduction of whole failures, because related power-cable failure represented 70% of ESP failures in 2015. Considering Super 13Cr instead of carbon-steel tubing gave positive indications, and reduced sharply related tubing-integrity failure. The problem still exists, however, with very low frequency. For surface equipment, all unforeseen SCSSV closures actuated from the control panel are always accompanied by a gradual decrement of frequency and, consequently, smoother ESP shutdown. Because our organization is the company that uses ESP with a proper sense in Algeria, this paper presents some best practices to be considered for other companies and ESP contractors that are based in the country or abroad that intend to install an ESP system in very high-salinity and corrosive fields and to adopt a lease model for downhole equipment.

Palynological study of the Pliensbachian-Toarcian transition of the Traras Mountains (northwestern Algeria)

Abstract: A palynological study of the Late Pliensbachian-Early Toarcian deposits in the Traras Mountains (NW Algeria) identified sporomorphs (spores and pollen grains) associated with acritarchs and algae unknown in this Algerian basin at this time. Seeking to characterize the Pliensbachian-Toarcian transition, the results of qualitative and quantitative analysis of pollen assemblages generated new stratigraphic information on the lower limit of Bayada beds which have already been established by ammonites, brachiopods and foraminifera.

Insight into the Tectonics of the Kaboudia Area and Related Petroleum Systems, Eastern Tunisian Offshore (Tunisia)

Abstract: The Kaboudia permit belongs to the Pelagian domain that has experienced extensional tectonics in the framework of the Tethys oceanic opening since Triassic. As the rest of the Northern African Mesozoic basins, peritethyan basins underwent a syn-rift opening during Late Triassic- Jurassic with coeval magmatic intrusions. This extensional period extended until Lower Cretaceous within the Tunisian basins. After Austrian uplift and erosional event, the former tectonic subsidence and extension was followed by a post-rift phase, which is marked by the deposition of a thick shale series of Fahdene during Albian-Cenomanian period. The Late Cretaceous to Eocene represents tectonically a quiet period that was characterized by the deposition of condensed sections and compressional periods such as, Santonian and Priabonian phases. Horst and grabens tectonics associated to a transtension occurred during Upper Miocene along the NW-SE extensional faults that are related to the Opening of the Tyrrhenian Sea and subsequent movement of Sicily with regard to Africa in the framework of the Ionian subduction. The Kaboudia permit conceals already oil accumulations within the Serdj and Allam Cretaceous carbonate reservoirs that are sourced from Lower Fahdene (Vraconian) source rock. After lab data, only few samples of such shale have shown a certain potential. However, Delta Log R method and seismic interpretation show source indications within the paleo-troughs around Mahdia structure and Kuriat furrow (near Taboulba). On the other hand, lab data shows also few samples from Allam and Serdj Aptian shale with higher TOC’s and residual potential S2. In terms of petroleum system working, the Mouelha could charge Allam limestone reservoir in a perdescensum. However, the reservoir below might be charged only when the latter is comprised within the same structural closure of the structure (trap). In addition, the Serdj reservoir could be charged downward by Allam and Mouelha shale within the kitchen zones. The postmortem analysis of exploration results at Kaboudia and the surrounding blocks, revels that the main risk regarding the petroleum system is the source rock potential, its extension and at a lesser degree the seal capacity.