Ahmed H. Kamel

A Comparative Investigation of Rheological and Flow Behavior Among Clean Polymeric and Surfactant Based Fluids

This study involves experimental investigation of rheological and hydraulic characteristics of aqueous based polymeric and surfactant fluids in straight and coiled tubing. The fluids matrix includes guar, HPG, PHPA, welan, xanthan, and surfactant. Bohlin rheometer was used to evaluate rheological and viscoelastic characteristics. For hydraulic characteristics, small- and large-scale flow loops were used.It is observed that all fluids exhibit comparable non-Newtonian behavior and improved viscous and elastic properties. Among polymeric fluids, guar and welan provide better viscosity and suspension properties. Surfactant is significantly affected by the formation of rod-like micelles and other microstructures. Master curves for rheological and elastic properties are developed using the molecular theory approach. The foremost benefit of these curves is its dimensionless form that provides a unique technique to predict viscosity for all fluids.For hydraulic properties, friction losses in coiled tubing are significantly higher than in straight tubing due to centrifugal forces and secondary flows. Surfactant is more sensitive to shear field applied where different microstructures are induced and thus they exhibit better drag reduction characteristics than polymeric fluids especially in coiled tubing with larger sizes. However, in straight tubing, guar shows better drag reduction characteristics than surfactant and other polymers, which diminishes as tubing size increases. However, welan gum exhibits a comparable performance. Overall, all fluids are considered good candidates as fracturing fluids with specific features for each. Unique characteristics of each fluid is discussed and explained in more details within the context of the present paper.Copyright

RJD: A Cost Effective Frackless Solution for Production Enhancement in Marginal Fields

With the worldwide trend of low oil prices, high maturity of oil fields, excessive cost of horizontal and fracking technologies, and necessity for green drilling applications, radial jet drilling (RJD) technology can be a cost effective and environmentally-friendly alternative. RJD is an unconventional drilling technique that utilizes coiled tubing conveyed tools and the energy of high velocity jet fluids to drill laterals inside the reservoir. In recent years, rapid advances in high pressure water jet technology has tremendously increased its application in oil and gas industry not only in drilling operations to improve drilling rate and reduce drilling cost, but also in production to maximize hydrocarbon recovery. In addition, RJD can be used to bypass near wellbore damage, direct reservoir treatments/injections, improve water disposal and re-injection rates, and assist in steam or CO2 treatments. This paper highlights the theoretical basis, technological advancement, procedures, applications, and challenges of high pressure water jets. Several worldwide case studies are discussed to evaluate the success, results, pros, and cons of RJD. The results show that nearly an average of four to five fold production increase can be obtained. The present paper clearly shows that radial jet drilling is a viable and attractive alternative in marginal and small reservoirs that still have significant oil in place to capture the benefits of horizontal drilling/fracking and to improve productivity from both new wells and/or workover wells that cannot be produced with the existing expensive conventional completions.

Model inference using the Akaike information criterion for turbulent flow of non-Newtonian crude oils in pipelines

The friction factor is a crucial parameter in calculating frictional pressure losses. However, it is a decisive challenge to estimate, especially for turbulent flow of non-Newtonian fluids in pipes. The objective of this paper is to examine the validity of friction factor correlations adopting a new informative-based approach, the Akaike information criterion (AIC) along with the coefficient of determination (R2). Over a wide range of measured data, the results show that each model is accurate when it is examined against a specific dataset while the El-Emam et al. (Oil Gas J 101:74–83, 2003) model proves its superiority. In addition to its simple and explicit form, it covers a wide range of flow behavior indices and generalized Reynolds numbers. It is also shown that the traditional belief that a high R2 means a better model may be misleading. AIC overcomes the shortcomings of R2 as a trade between the complexity of the model and its accuracy not only to find a best approximating model but also to develop statistical inference based on the data. The authors present AIC to initiate an innovative strategy to help alleviate several challenges faced by the professionals in the oil and gas industry. Finally, a detailed discussion and models’ ranking according to AIC and R2 is presented showing the numerous advantages of AIC.

Statistical significance and hypothesis for friction factor correlations of non-Newtonian crude oils in pipelines

In pipelines, non-Newtonian fluids are generally pumped under turbulent flow conditions where frictional pressure losses are required for hydraulic design. The friction factor is a crucial parameter in calculating frictional pressure losses. However, determination of the friction factor is a decisive challenge, especially for turbulent flow of non-Newtonian fluids. This is mainly due to the large number of friction factor equations and the precision of each.The main objective of the present paper is to evaluate the published friction factor correlations for non-Newtonian fluids over a wide range of friction factor data to select the most accurate one. An analytical comparative study adopting the recently introduced Akaike information criterion (AIC) and the traditional coefficient of determination (R2) is conducted. Data reported by several researchers are used individually and collectively.The results show that each model exhibits accuracy when examined with a specific data set while El-Emam et al. model proves its superiority to other models when examining the data mutually. In addition to its simple and explicit form, it covers a wide range of flow behavior indices and generalized Reynolds numbers.It is also shown that the traditional belief that a higher R2 corresponds to better models may be misleading. AIC overcomes the shortcomings of R2 as it employs the parsimonious principle to trade between the complexity of the model and its accuracy not only to find the best approximating model but also to develop statistical inference based on the data. Although it has not yet been used in oil and gas industry, the authors present the AIC to initiate an innovative strategy that has been demonstrated in other disciplines to help alleviate several challenges faced by professionals in the oil and gas industry. Finally, a detailed discussion and models’ ranking according to AIC and R2 is presented showing the numerous advantages of AIC.Copyright