Abstract It is found in the literature that correlations and methods used in the determination of the lifting capacity for vertical wells cannot be applied directly for calculating the lifting capacity for horizontal well section without modifications. It is therefore necessary to formulate a new experimental technique from which new lifting capacity correlation is deduced which will be applied for the determination of the lifting capacity for the horizontal well section.The phenomena of cuttings concentration accumulated in the bottom of the horizontal section which is present in horizontal wells, does not exist in the vertical sections of the well. This problem makes it necessary to conduct an experimental work in a horizontal well simulator, to exactly simulate the drilling operation in the horizontal section of the well, from which lifting capacity values are determined for different mud formulations containing different cuttings sizes, concentrations and different mud reheology circulation at different flow rates. The objective of this study is to investigate the behavior of whole cleaning in the horizontal well section and to determine the factors effecting the cleaning capacity of the mud in this section. Also to deduce correlations relating the lifting capacity of the mud in the horizontal section of the well with various drilling parameters and mud circulation conditions. This study is conducted in the laboratory using a horizontal well simulator consists of the circulating mud component similar to that present in actual drilling operations. The experimental work used consists of using four muds formulation systems mixed with different cutting sizes and concentrations. The returned cuttings are extracted from mud return line for selected given time increments and accordingly their weights and sizes are determined. It is concluded that there is an optimum cutting size for maximum lifting capacity for each cutting concentrations used. The lifting capacity observed form the experimental results is not only dependent on mud velocity, but it is also dependent on the cutting concentrations used. It was observed that when cleaning the system after each experiment, accumulation of rock cuttings were present in the bottom of the horizontal section of the model. In this study a lifting capacity correlation relating the lifting capacity with mud flow rate, cutting size, cutting concentration, mud density, and mud viscosity is generated for the horizontal section of the well. Therefore it recommended that cleaning of the horizontal section of the well should be conducted frequently (consecutively) after each drilling time increment, which means that the drilling operation is stopped and the mud circulation rate is set to maximum. A maximum mud circulation rate is needed in order to ensure that the cuttings generated by the bit are removed efficiently in the horizontal section. It is therefore recommended during drilling the horizontal section a sequential drilling and cleaning technique should be applied.
عادل محمد جالوتة (2010)

Abstract Formation damage caused by inappropriate drilling, completion, work over and production schemes are a major cost to the oil and gas industry worldwide. Many potential pay zones have been misdiagnosed as nonproductive and payout on investment has often been delayed. The reservoir rock and resident fluids are essentially in a state of physicochemical and thermodynamic equilibrium. Disruptions in this equilibrium due to changes in pressure, temperature and fluid chemistry around the well bore region can create barriers to flow and yield lower production rates.Scale deposition is one of the most serious oil field problems primarily when two incompatible waters are involved .Two water types are called incompatible if they interact chemically and precipitate minerals when mixed .Typical examples are sea water, with high concentration of ,and formation water, with high concentration of ,and .Mixing of these types of water could cause CaSO4,BaSO4,and SrSO4 scales.In this research we analyzed pressure transient for different oil wells in Amal Field. The collected data as well as reservoir rock and fluids properties and well bore conditions and configuration was being inserted into MINITAB program to formulate mathematical model which can predict total skin in oil wells .We observed that model gives good results when we compared St calculated from build up test with St calculated from the model. A Mathematical Model was developed in this study which can be used by the production engineer in any sandstone reservoir in order to predict the possibility of damage forming in the well.The model can also be utilized to define the parameters causing the damage in the well from which adjustment can be made to reduce the chance of forming damage in the well bore.
عبد المحسن عاشور مقام (2008)

Abstract The average recovery factor calculated for the whole reservoir is higher than the average recovery factor calculated from averaging the individual well recovery factor. The integrated recovery factor calculated from each well should be compared with recovery factor calculated for the reservoir as a whole using the material balance equation or the volumetric methods as a basis for the calculations. The difference between the two values is anindication of an inadequate well spacing for the reservoirIf (Np/N) each ≈ (Np/N)whole the distribution of the wells for the reservoir is adequate .If (Np/N) each < (Np/N)whole the distribution of the wells in the reservoir is inadequate .This indication of excess in number of wells .If (Np/N) each > (Np/N)whole the distribution of the wells in the reservoir is inadequate .This indication of the reservoir needs infill wells to be drilled.The number of infill wells depends on the relationship between recovery factor and number of wells. The infill wells location in the reservoir should be at high hydrocarbon pore volume and also it should be located in the trend of the easiest permeability path of oil movement.It was concluded that the number of wells existing in the Sharara field is not adequate therefore we recommend to increase the number of the wells as per the method enclosed in this study. The results of this study indicate that the calculated oil production decline rate constant is different from well to another which is an indication of variations of water influx into the reservoir.
مختار محمد غدير (2008)