Abdul Razak Ismail

Monitoring Foam Stability in Foam Assisted Water Alternate Gas (FAWAG) Processes Using Electrokinetic Signals

The natural pressure in hydrocarbon reservoirs is only sufficient in producing small amount of hydrocarbon at the end of the depletion stage. Therefore, in order to enhance or increase the hydrocarbon recovery, water or other fluids are injected into the formation to extract the hydrocarbon from the pore space. This common practice is known as Improved or Enhanced Oil Recovery (IOR or EOR). Foam is purposely used in some of the EOR displacement processes in order to control the mobility ratio, hence improving the volumetric sweep efficiency. The efficiency of a foam displacement process in EOR depends largely on the stability of the foam films. In laboratory, foam stability is usually measured through physical observation of the foam bubble in a glass tube. Unfortunately, this direct observation is not possible in the reservoir. Therefore, indirect measurement such as the measurement of electrokinetic signal would be a better alternative. This study aims to determine the correlation between the foam stability and the associated streaming potential signals which resulted from the flowing fluid in foam assisted water alternate gas (FAWAG) process. The experimental work will be conducted at the Reservoir and Drilling Engineering Laboratories at the Faculty of Petroleum and Renewable Energy Engineering (FPREE), UTM. The investigation includes sample preparation, sample analysis, displacing fluid formation, rheological properties test and electrokinetic signal measurement by using NI Data Acquisition System (NIDAS). It is expected that the burst of the foam bubble will change the pattern of the electrokinetic signals. The research findings could lead to a new approach in monitoring a FAWAG process. Application in the real field could benefit the oil and gas industry in term of making the EOR process more efficient and more economic.

The Effect of Solids Concentration and Formation Characteristics on Formation Damage and Permeability Recovery

An experimental study has been made. to investigate the effect of solids concentration and fdtcr media on fluid loss and permeability recovery of cores. KClpolymer muds of different”barite concentrations and different types of core were used to perform the tests. Filtration tests showed that fluid loss increased as solids concentration” in the mud increased. Increasing the @ids cone.en.trati~n in the mud appems to improve perrneablhty recovery when the cores were backfhrshecf. However, high spurt 10SS and poor permeability recovery were observed if muds.. contairiliig” polymer materials were used without the addition of solid particles. Filtration and perrneabifity restoration are not orily affected by the sire, shape and solids concentration in the mud but also to the pore size distribution and core characteristics.. Detded observation using scanning electron microscope was used to identify the solids impairment at the core face. Therefore, to reduce formation damage and improve recovery, suitable size, shape and concentration of solids in the mud must be properly selected. .. ..=,.. . . .=–= References and illustrations at the end of paper. INTRO DUCT16N. .“ Forination damage and borehole filtratiori we very importznt esp’ecially in drilling and completion operations. Any filtrate lost and particle invasion into the exposed section adjacent to the .yeflbo~ will be a potenti@_source of damage. Irr some cases the fdtrate may react with me drilled formation and cause rn&chaoi@ instabuity to the borehole. Damage tlom mud solids is strongly, dependent on @e pore size ~: distribution of the formation, the particle size distribution in the drilling fluid and on the wellbore overbalance pressure. Inviiiori ..occrrrs with all muds during drilfirrg. However, it is possible tominimifi solids invasion and formation impairment by adding bridging material to the muds. Investigators I-3 have shown mat the bridging of pores by particles is required to Riitiate fiiter cake formation. This bridging material is chosen by matching its size to the foirnation rock . pore s]zes. A bridge maybe irriti&d when two large particles stat to move into an opening at the same time and lodge against each other. Other smaller paxticles may be bridge the openings between the larger, previously bridge particles. If the proper particle sizes are present, this process may contiriue until the openings become too small for any contained solids to penetrate. It is at this time that only the filtrate flows thrmrgh the ftiter cake.

Synthesis of Titania-bentonite Nanocomposite and Its Applications in Water-based Drilling Fluids

Titania or TiO2-bentonite nanocomposite was synthesised by environmental friendly and cost effective hydrothermal method. Synthesised nanocomposite was successfully characterised by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). The target of the study was to enhance the rheological behaviour of the water-based drilling fluid (WBDF) by using synthesised nanocomposite. The experimental results revealed that Titania-bentonite nanocomposite exhibited better rheological characteristics than conventional WBDF. Rheological properties in particular yield point (YP) and 10-min gel strength (10-min GS) were improved by 57 % and 40 % compared to basic drilling fluid after addition of 1.0 g of the synthesised nanocomposite at 65.56 °C. API filtrate loss volume and High Pressure High Temperature (HPHT) filtrate loss volume were slightly reduced by 10 %, and 9.2 %. These scientific results can be used to formulate enhanced WBDF at elevated temperatures.

Adsorption of aerosol-OT on sand and shale at high sodium salt concentration

Surfactant flooding is a method for additional recovery of oil from partially depleted reservoirs by changing the interfacial tension. During the application of surfactant into a reservoir, a certain loss in the high equivalent weight fraction occurs. These surfactant molecules are the most efficient in lowering the interfacial tension between reservoir brine and crude oil. Introducing the surfactant to rock sediment may result in these losses and increase the partition or adsorption of hydrocarbon organic compounds (HOCs) in the rock-water system. The adsorptive behaviour of Aerosol-OT was studied under high salt concentration at room temperature in the presence of sandstone and shale. This study detected the adsorption based on the monitored changes in the initial concentration of the surfactant. The adsorption of the surfactant Aerosol-OT has been investigated using batch adsorption isotherms and the technique of UV-Vis spectroscopy. The objective of the study was to gain further insight into the surfactant adsorption for these adsorbents and to determine the appropriate isotherm model. The equilibrium results showed that the value of concentration changed from 0.03 g/L to the lowest value of 0.0124 g/L, which is lower than half. The batch adsorption isotherms that Aerosol-OT adsorption behaviour followed was found to fit Langmuir-Frandluich model.

Wettability Alteration of Dolomite Rock Using Nanofluids for Enhanced Oil Recovery

Wettability alteration of rock by surfactant has been considered as feasible method for recovery of oil reservoirs by modifying the wettability of rock surface from oil-wet to water-wet condition. The impact of surfactant can be enhanced by adding nanoparticles. Cationic surfactant performed well in carbonate rock by forming ion pairs between cationic head and acidic component of the crude. Meanwhile, nanoparticles will form continuous wedge film between the liquid and solid surface. In this paper, Al2O3 and ZrO2 nanoparticles were used as enhanced oil recovery (EOR) agents. The impact of these two nanoparticles on contact angle and interfacial tension was studied. Besides that, adsorption Cetyltrimethylammonium Bromide (CTAB) surfactant on rock surface was also investigated. The results show a significant change in water-oil contact angle after application of surfactant and nanoparticles. Initial water-oil contact angle for 6 dolomites demonstrate oil-wet condition. Then, the dolomites were submerged in prepared solution for 48 hours. The result shows that, dolomites 2, 5 and 6 changes drastically to more water-wet condition with contact angle 56°, 40° and 47° respectively. For surfactant adsorption, the adsorption is very fast at the beginning. The adsorption rate after 5 minutes was 50 mg/g and after 60 minutes the adsorption rate was 310 mg/g. The adsorption rate slowed down after 60 minutes and after 180 minutes the adsorption rate was 315 mg/g in which the rate of adsorption achieve equilibrium. Nanoparticles retention test and Zeta potential shows that Al2O3 is more stable than ZrO2. The results for interfacial tension (IFT) also show a significant reduction. The IFT value reduces from 8.46 mN/m to 1.65 mN/m and 1.85 mN/m after the application of Al2O3 and ZrO2 nanofluids respectively

Nanoparticles Performance as Fluid Loss Additives in Water Based Drilling Fluids

Nanoparticles are used to study the rheological characteristics of drilling fluids. Nanoparticles have high surface to volume ratio, therefore only small quantity is required to blend in the drilling fluid. This research evaluates the performance of nanosilica and multi walled carbon nanotubes (MWCNT) as fluid loss additives in water based drilling fluid with various nanoparticles concentration and temperature. The results show that plastic viscosity, yield point and gel strength of drilling fluid increases as the concentration of nanoparticles increased. Drilling fluid with nanosilica gives the highest filtrate loss of 12 ml and mudcake thickness of 10 inch at 1 g concentration at 300°F. However, drilling fluid with MWCNT shows a decreasing trend in fluid loss and mudcake thickness. The results also show that xanthan gum containing 1 g of MWCNT gives 4.9 ml fluid loss and mudcake thickness of 4 inch at 200°F. After aging, plastic viscosity, yield point and gel strength of mud containing nanoparticles decrease significantly especially for 1 g of nanosilica and 0.01 g MWCNT. Fluid loss and mudcake thickness increased when the mud is exposed to temperature above 250°F. The results showed that xanthan gum with MWCNT gives a better rheological performance.

Reservoir Monitoring Using Streaming Potential; Is the Thermoelectric Correction Necessary?

Wellbore streaming current and their applicability in the location of subsurface sand bodies were discovered in 1931 and the usefulness of this measurement has persisted to the present day. Through the endeavor of many researchers, knowledge and understanding of streaming potential (SP) have slowly evolved from the original mere recognition of its existence to its present-day quantitative use in many applications such as Enhanced Oil Recovery (EOR), water flooding, intelligent wells, etc. The spontaneous potential acts to maintain overall electroneutrality when a separation of electrical charge occurs in response to gradients in pressure (Electrokinetic), chemical composition (Electrochemical), or temperature (Thermoelectric). In spite of it being discovered 70 years ago, unfortunately little work has been done to find measurable value especially for thermoelectric coupling coefficient. Many researchers attempt to generate a universal model for SP. They attributes the limitations (if any) of their model to the scarce availability of accurate estimation for coupling coefficient. This study measures the value of thermoelectric coupling coefficient for five rock samples saturated with 0.01M (NaCl) saline brine. The study takes account of temperature dependant electrode effect. The result shows value of 0.2 mV/K, which is in a good match with most of the published data. It was also found that there is no strong correlation between the thermoelectric coupling coefficient and porosity. The measured thermoelectric values are considered insignificantly small compared to the electrokinetic effect in the system.

Monitoring Water Alternate Gas (WAG) Process Using Streaming Potential Measurement

Spontaneous potential (SP) is commonly measured during reservoir characterization. SP signals are also generated during hydrocarbon production due to the streaming potential occurrence. Measurement of SP could be used to detect and monitor water encroaching on a well. SP signals could also be monitored during production, with pressure support provided by water alternate gas (WAG) process. The objectives of this study are to quantify the magnitude of the SP signal during production by WAG injection and to investigate the possibility of using SP measurements to monitor the sweep efficiency. Measurement of streaming potential has been previously proposed to detect the water encroachment towards a production well. The peak of the signal corresponds to the waterfront where there is a change of saturation from ionic water to non-polar hydrocarbon. Similar trend is predicted in the case of WAG where we have several interfaces between the injected water and the injected gas. The results indicate that the magnitude of the SP generated in hydrocarbon reservoir during WAG process can be large and peaks at the location of the moving water front. Gas, which can be assumed to be non-polar, exhibit no electrokinetic effect. These observations suggest that WAG displacement process can be monitored indirectly from the signal acquired. Water or gas override can be detected and controlled if wells were equipped with inflow-control valves. As a conclusion, the SP measurement is a promising method to monitor the effectiveness of a WAG process. This study is significant because monitoring the progress of water and gas in a WAG process is key in the effectiveness of this enhanced oil recovery method. Measurement of the streaming potential provides another method besides using tracers to monitor the WAG profile. Better monitoring will lead to more efficient displacement and great benefits in term of economy and environment.

Effect of distance intermittent ultrasonic wave source on the surfactant-polymer flooding recovery and its displacement pattern

The ultimate recovery factor of primary and secondary recovery process can be up to approximately 40 % of oil in place. Technology development is required in order to improve and maximise the recovery and recover some of the oil left. Enhanced Oil Recovery (EOR) method been introduced to solve the main issues of poor recovery, and theoretically, Surfactant-Polymer (SP) flooding would be the EOR method that are able to maximise both, sweep and displacement efficiency. Application of ultrasonic waves and pulse vibrations in the reservoirs has been noticed to reduce the interfacial tension (IFT) between oil and water, resulting in reduction of capillary pressure in the pores and therefore, resulted to an improvement on oil recovery. Ultrasonic waves are longitudinal mechanical waves, which are generated by an infinitesimal compression of a medium. It is known that propagation of the sound waves depends on the elasticity, grain size and density of the rock. It is not certain how far an acoustic wave propagates into the reservoir, nor how such propagation occurs. The theory expects ultrasonic waves to be present in the reservoir because dispersion of low frequency waves within porous media forms high frequency harmonics (ultrasonic noise). The main focus of this research is to initiate the use of intermittent ultrasonic radiation in assisting SP flooding process under microscopic visualisation and how it enhances oil recovery through the reduction of residual oil saturation. This work has been designed to understand the mechanics of intermittent ultrasonic vibration in influencing additional recovery of SP flooding. This research is important to know more on how intermittent vibration influences the wave propagations inside the porous media. To achieve this, series of experiments consisting of visualisation and displacement experiments were conducted by using micro-model and macro-model, respectively. SP flooding with aid of ultrasonic waves was compared with normal SP flooding process. Distance of ultrasonic energy source from porous media, d, also was changed to monitor their influence on the process. Snapshots of oil displacement of glass micro-model were taken for visualisation purposes. Reduction of residual oil saturation for displacement process by using macro-model porous media were recorded. The outcomes justified that intermittent vibrations can produce and enhance more additional oil recovery of SP flooding compared to the continuous vibration, and the distance of ultrasonic energy source highly affects the residual oil left in the porous medium after SP flooding.

Monitoring Water Alternate Gas Process Using Streaming Potential

Spontaneous potential (SP) is commonly measured during reservoir characterisation. SP signals are also generated during hydrocarbon production due to the streaming potential occurrence. Measurement of SP has been proposed as a method to detect and monitor water encroachment. In principle, SP signals could also be monitored during production from a single well, with pressure support provided by a water alternate gas (WAG) process. The objective of this study is to monitor WAG process by using streaming potential measurement. SP signal will be measured during production by WAG injection. Measurement of streaming potential has been previously proposed to detect the water encroachment towards a production well. The peak of the signal corresponds to the waterfront where there is a change of saturation from ionic water to non-polar hydrocarbon. Similar trend is predicted in the case of WAG where we have several interfaces between the injected water and the injected gas. This project involved experimental work. The investigation comprised physical model design for WAG process, model characterisation, and correlation between SP signals WAG performance. WAG displacement process could be monitored indirectly from the signal acquired. SP measurement is a promising method to monitor the effectiveness of a WAG process. This study is significant because monitoring the progress of water and gas in a WAG process is a key in the effectiveness of this enhanced oil recovery method. Measurement of the streaming potential provides another method besides using tracers to monitor the WAG profile. Better monitoring will lead to more efficient displacement and great benefits in term of economy and environment.