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An understanding of the mechanisms by which oil is displaced from porous media requires the knowledge of the role of wettability and capillary forces in the displacement process. The determination of representative capillary pressure ( ) data and wettability index of a reservoir rock is needed for the prediction of the fluids distribution in the reservoir: the initial water saturation and the volume of reserves. This study shows how wettability alteration of an initially water-wet reservoir rock to oil-wet affects the properties that govern multiphase flow in porous media, that is, capillary pressure, relative permeability, and irreducible saturation. Initial water-wet reservoir core samples with porosities ranging from 23 to 33%, absolute air permeability of 50 to 233 md, and initial brine saturation of 63 to 87% were first tested as water-wet samples under air-brine system. This yielded irreducible wetting phase saturation of 19 to 21%. The samples were later tested after modifying their wettability to oil-wet using a surfactant obtained from glycerophtalic paint; and the results yielded irreducible wetting phase saturation of 25 to 34%. From the results of these experiments, changing the wettability of the samples to oil-wet improved the recovery of the wetting phase.

Horizontal wells have become a popular alternative for the development of hydrocarbon fields around the world because of their high flow efficiency caused by a larger contact area made with the reservoir. Most of the analytical work done in the past on horizontal productivity either assumed that the well is infinitely conductive or the flow is uniform along the entire well length. The infinite conductive assumption is good only when the pressure drop in the wellbore is very small compared to the drawdown in the reservoir otherwise the pressure drop in the wellbore should be taken into account. In this paper, an improved predictive model that takes into account the effect of all possible wellbore pressure losses on productivity index of long horizontal well was developed. Results show that the discrepancies in the predictions of the previous models and experimental results were not only due to effect of friction pressure losses as opined by Cho and Shah but may also be due to all prominent pressure losses such as kinetic change and fluid accumulation experienced by the flowing fluid in a conduit. The effect is most pronounced at the early production time where initial transience at the onset of flow is experienced.

Proper slurry design is critical to the success of a cementing job. The best method to obtain a good slurry design with desired compressive strength is by laboratory experiments which involve experimenting different formulations and selecting the best composition for the specific cementing operation. This exercise is not only time consuming considering the amount of time required, but also expensive. Sixteen sets of experiments were conducted in the laboratory, and factorial design was used to design the experiments for the sensitivity analysis of four different factors impacting on the compressive strength of cement slurry. The responses from the 16 experimental runs were used to develop a model which can be used for optimization purposes. The model developed was simple, in agreement with the experimental data used and can be implemented using an ordinary simple calculator. Coefficients of main effects of X 1 , X 2 , X 3 , and

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