K.A. Fattah

The Influence of XC-Polymer on Drilling Fluid Filter Cake Properties and Formation Damage

The filter cake characterization is very essential for doing well selection of the drilling fluids that eliminates the drilling problems such as formation damage. A correct knowledge of filter cake properties gives petroleum engineers a tool for efficiently managing hydrocarbon production process of a field. This study aimed to experimentally investigate the effect of different concentration of XC-Polymer on filter cake properties, filtrate loss and formation damage to select the optimum concentration of the XC-Polymer. High Pressure-High Temperature (HPHT) filter press with ceramic disk device was used to conduct these experiments. Seven samples of water-based drilling were used in this study. The chemical compositions of the filter cake were described by using Scanning Electron Microscopy (SEM). The results show that the optimum concentration of the XC-Polymer in current study is 1.0 lb/bbl (1 g/ 350 ml); it was observed that 1g XC-Polymer per 350 ml of the drilling fluid is sufficient for appropriate optimum rheological efficiency. However, if more than 2 g. of XC-Polymer is added, the fluid loses its property and becomes almost immobile. Thus, at 1.0 g of the XC-Polymer concentration there is a less reduction in permeability of the ceramic disk. At this concentration, we got less reduction in permeability of ceramic disk and good properties of the filter cake. In addition, this is an indicator of less formation damage at this concentration of XC-Polymer.

New Modified Black-Oil Correlations for Gas Condensate and Volatile Oil Fluids

Several authors have shown the applicability of modified black oil (MBO) approach for modeling gas condensate and volatile oil reservoirs. It was shown before that MBO could adequately replace compositional simulation in many applications. In this work, a new set of MBO PVT correlations was developed. The four PVT functions (oil-gas ratio, Rv, solution gas-oil ratio, Rs, oil formation volume factor, Bo, and gas formation volume factor, Bg) were investigated. According to our knowledge, no other correlation for calculating oil-gas ratio exists in the petroleum literature. Alternatively, oil-gas ratio (needed for material balance and reservoir simulation calculations of gas condensate and volatile oil reservoirs) had to be generated from a combination of laboratory experiments and elaborate calculation procedures using EOS models. In previous work, we found that Whitson and Torp method for generating Modified Black Oil (MBO) PVT properties yielded best results when compared with compositional simulation. This method (and the others available in the literature such as Coats’ and Walsh’s) requires the use of data from PVT laboratory experiments and proper construction of EOS models. We used Whitson and Torp’s method to generate our database of the MBO PVT curves used in developing our correlations after matching the PVT experimental results with an EOS model. For each one of the four PVT parameters, we used 1850 values obtained from PVT analysis of eight gas condensate fluid samples and 1180 values obtained from PVT analysis of five volatile oil fluid samples. The samples were selected to cover a wide range of fluid composition, condensate yield, reservoir temperature, and pressure. The data points were generated by extracting the PVT properties of each sample at six different separator conditions. We then used multi-variable regression techniques to calculate our correlation constants. The new correlations were validated using the generalized material balance equation calculations with data generated from a compositional reservoir simulator. These new correlations depend only on readily available parameters in the field and can have wide applications when representative fluid samples are not available.

Utilization of Shredded Waste Car Tyres as a Fracture Seal Material (FSM) in Oil and Gas Drilling Operations

The drilling operation cost represents 25% of the total oilfield exploitation cost. Drilling fluids represent 15 to 18% of the total cost of well petroleum drilling operations. The main drilling fluids problem is the loss into fractures and vugs. Mitigation of severe lost circulation is a main challenge while drilling in fractured formations where conventional lost circulation materials (LCM) will not cure these losses. Therefore, specialized fracture seal material (FSM) is required when drilling fractured formations. In this study, a promising FSM made from shredded waste car tyres was tested at laboratory for its ability to seal artificially fractured cores under High Temperature High Pressure (HT-HP) conditions similar to wellbore conditions. For this purpose, the conventional 500 ml HT-HP filtration cell was modified to accommodate a fractured core plug of length and diameter equal to 38.1 mm (1.5 inches) instead of the ceramic disc. Moreover, the cell outlet channel located below the fractured plug was increased from 1.0 mm diameter to 5.0 mm to easily allow the passage of the FSM in none effective fracture seal tests. Using the modified HT-HP filtration cell shredded waste car tyres proved its ability to perfectly seal the artificially made fracture in the test core samples at overbalance pressures up to 900 psi and temperatures up to 80°C. The optimum mud composition was fresh water, 7% by weight bentonite, 7% shredded waste car tyres (a mixture ranging between 2.3 mm and less than 0.45 mm granule sizes) in weight bases. In addition to its great ability to seal fractured formation, the shredded waste car tyres material is cheap and locally available in commercial quantities. Additionally, the utilization of waste car tyres in drilling operations and other industrial applications can protect the environment from many hazards.

Utilization of shredded waste car tyres as a fracture seal material (FSM) in oil and gas drilling operations

The drilling operation cost represents 25% of the total oilfield exploitation cost. Drilling fluids represent 15 to 18% of the total cost of well petroleum drilling operations. The main drilling fluids problem is the loss into fractures and vugs. Mitigation of severe lost circulation is a main challenge while drilling in fractured formations where conventional lost circulation materials (LCM) will not cure these losses. Therefore, specialized fracture seal material (FSM) is required when drilling fractured formations. In this study, a promising FSM made from shredded waste car tyres was tested at laboratory for its ability to seal artificially fractured cores under High Temperature High Pressure (HT-HP) conditions similar to wellbore conditions. For this purpose, the conventional 500 ml HT-HP filtration cell was modified to accommodate a fractured core plug of length and diameter equal to 38.1 mm (1.5 inch) instead of the ceramic disc. Moreover, the cell outlet channel located below the fractured plug was increased from 1.0 mm diameter to 5.0 mm, easily allow the passage of the FSM in none effective fracture seal tests. Using the modified HT-HP filtration cell, shredded waste car tyres proved its ability to perfectly seal the artificially made fracture in the test core samples at overbalance pressures up to 900 psi and temperatures up to 80°C. The optimum mud composition was fresh water, 7% by weight bentonite, 7% shredded waste car tyres (a mixture ranging between 2.3 mm and less than 0.45 mm granule sizes) in weight bases. In addition to its great ability to seal fractured formation, the shredded waste car tyres material is cheap and locally available in commercially quantities. Additionally, the utilization of waste car tyres in drilling operations and other industrial applications can protect the environment from many hazards. n n xa0 n n Key words: HT-HP filtration, Fracture seal, shredded waste car tyres, drilling fluid, fractured core plug.