Optimizing oil production in horizontal wells (water/oil cresting in horizontal wells)

In recent years, the application of horizontal wells has been predominant in minimizing cresting scenarios due to significant reservoir exposure of its laterals. Cresting is known to occur in horizontal wells when the pressure drop supersedes the hydrostatic pressure existing between the phases in a typical reservoir. Cresting poses problems such as uneconomic oil production rates due to increasing volumes of effluent(s) (unwanted water and or gas) produced with oil over time as well as the overall recovery efficiency of oil reservoirs. Production optimization from crest-affected thick- and thin-oil rim homogeneous reservoirs were investigated experimentally by considering the effect of varying the inclined sections of a horizontal well at low angles of inclination (15o-30o), initial surface pressures (-4.351Psig), lateral length in reservoir (lr, = 0.305 m) and oil viscosity (50 cP) on oil recovery, oil produced and cumulative water produced during cresting. A strong bottom aquifer and considerable gas cap were modeled at constant bottom water injection rate of 41.68 cm3/s and at atmospheric pressure (14.7 Psi) respectively. An experimental proactive cresting control technique based on reservoir wettability, gravity segregation and effluent(s) breakthrough times were investigated for cresting control in thick- and thin-oil rim homogeneous reservoirs, using an electromagnetic valve installation. Numerical simulations were considered using Particle Image Velocimetry (PIV) to the determine the velocity of captured water cresting images and Computational Fluid Dynamics (CFD) to validate the oil withdrawal rate, Gas-Oil-Contact (GOC) and Water-Oil-Contact (WOC) by applying boundary conditions from the physical model. From results of varying the inclined section of the horizontal well, the Short radius wells with 30o angle of inclination and ratio of vertical displacement of the inclined section to reservoir height (Vd/Hr) of 0.079 resulted in 177.75 cm3 increment in oil recovered and reduction in cumulative water produced (258 cm3) at a production time of 300 s in thick-oil rim reservoirs while 250 cm3 increment in oil was observed with 356 cm3 reduction in cumulative water produced at a production time of 495 s in thick-oil rim reservoirs with Vd/Hr, 0.063. Further increment of 108.91 cm3 in oil produced and reduction in cumulative water produced (183.99 cm3), was observed when cresting was controlled proactively in thick-oil rim reservoirs. From varying the inclined section of the horizontal well, increment in oil produced of 163 cm3 and 134 cm3 cumulative reduction in produced water were observed at Vd/Hr equals 0.079 in thin-oil rim reservoirs at a simulation time of 210 s while a lower oil increment of 6.84 cm3 and cumulative water reduction of 10.98 cm3 were observed in thin-oil rim reservoirs when controlled proactively. The over predicted quantitative results as high as 75.06% using the CFD model compared with experimental data were due to two-dimensional (2D) model limitations in porous media as well as the corresponding grain sizes. To exemplify, for WOC the predicted results was about 28.56% compared to experimental data at 4.5 s. The average velocity profile from PIV analysis increased steadily from 0.113 to 2.08E-15 m/s from 10 to 90 s

Water/oil cresting in horizontal wells : a sensitivity study

This work presents a rigorous sensitivity analysis on cresting using a physical model, to investigate the effects of varying inclined section of horizontal well, lateral length in reservoir and oil viscosity on oil recovered, cumulative of water produced and Water Cut in thick- and thin-oil rim homogeneous reservoirs faced with strong bottom aquifer and considerable gas cap. From the results, it was observed that the geometry of the horizontal well and location of the bottom water injection points significantly influence the cumulative liquid produced, particularly in thin-oil rim reservoirs. The cumulative water produced and cumulative Water Cut were found to increase with increase in oil viscosity. The oil recovered from the thin-oil rim reservoir, were as high as 17.84% and 24.92% for oil viscosity of 50 cP and 100 cP respectively whereas 19.15% and 13.93% were observed for cumulative water produced from the thick-oil rim reservoir at 50 cP and 100 cP respectively

Effectively optimizing production of horizontal wells in homogeneous oil reservoirs

Horizontal well applications have been predominant since their conception, for reasons such as effective depletion of oil reservoirs and especially in water cresting, gas cresting or water and gas cresting applications due to the casings enhanced exposure to the reservoir. Cresting is hugely dependent on oil production rate, pressure drawdown and can negatively influence the degree of depletion as well as the overall recovery efficiency of oil reservoirs. This paper presents a novel procedure of mimicking horizontal wells aimed at investigating experimentally the effect of varying inclined sections (having different vertical and horizontal displacements) of horizontal wells at low angles of inclination (15o-30o) in a homogeneous reservoir underlain by a strong bottom aquifer and overlain by a considerable gas cap drive occurring simultaneously. The results for the performance of the different horizontal well geometries in terms of cumulative oil recovery and Water-Oil-Ratio; over a fixed liquid production time were compared. From the results obtained, it was observed that the short radius well with 30o angle of inclination and ratio of vertical displacement of the inclined section to reservoir height of 0.07 resulted in the highest oil recovery of 38.73%. Using the presented procedure, 5.60% increment in oil was recovered with 11.40% reduction in cumulative produced water were observed between the best and worst cases from the same reservoir. At higher withdrawal rates and pressure drop, long radii wells are recommended due to cresting delay ability while improving oil recovery

Effect of impermeable barrier orientation on bottom water cresting

The use of either a permeable or semi-permeable barriers has been proven to be effective in minimizing cresting effects in oil reservoirs characterized by strong bottom aquifer, with the latter known to be more effective. Most research has been focused on coning control in vertical wells with little research existing for cresting control in horizontal wells, especially in use of barriers. Therefore, this paper sets out to numerically investigate the effect of an impermeable barrier orientation in an oil reservoir characterized by a strong bottom aquifer. The orientations considered in this study were horizontal and inclined (step-like) in terms of placement in the oil reservoir, modeled with similar thickness and width. From the results, it was observed that a horizontally-placed impermeable barrier is more effective than inclined impermeable barriers in bottom water cresting scenarios. A horizontal impermeable barrier closer to the perforation of the horizontal well, 0.08x in thickness to the reservoir height and 0.45x to reservoir width was the most effective, although the effect of impermeable barrier width was found to be inconsistent with the performance of impermeable barriers. The study shows that the closer the entire top surface of the inclined impermeable barrier, the more effective the inclined impermeable barrier in minimizing bottom water cresting effect. The value of Reynolds number was found to be dependent on the orientation, thickness, position, and width of an impermeable barrier

Proactive control of cresting in homogeneous oil reservoirs : an experimental study

Cresting in horizontal wells is a well-known reservoir problem usually described as the insurgence of effluent(s) (unwanted water and or gas) through the perforation of the well, which is produced together with oil. Cresting is majorly affected by pressure drop, resulting in uneconomic oil production rates and large volumes of oil could be left behind due to premature shut-in of the well. This study experimentally investigates the use of electromagnetic valve in proactively controlling production of water during cresting from homogeneous thick- and thin-oil rim reservoirs, based on the principle of capillarity (reservoir wettability) and effluents (water and gas) breakthrough time. A time, half the approximated initial effluents breakthrough time, was pre-set for the electromagnetic valve to close. The valve closed almost immediately at the set-time thereby shutting oil production temporarily, causing the water and gas height levels to recede by gravity and capillarity. The efficiency of this technique was compared with an uncontrolled simulation case, in terms of cumulative oil produced and water produced at the same overall production time. Using the cresting control procedure, higher percentages in oil produced and water reduction were observed in the cases controlled proactively. An increment of 3.56% in oil produced and decrement in cumulative water produced of 9.96% were observed for the thick-oil rim reservoir while little increment in oil produced of 0.7% and lower water reduction of 1.03% were observed in the thin-oil rim reservoir. Hence, the effectiveness of the cresting control procedure depends on the oil-column height in the reservoir

SPARC 2017 retrospect & prospects : Salford postgraduate annual research conference book of abstracts

Welcome to the Book of Abstracts for the 2017 SPARC conference. This year we not only celebrate the work of our PGRs but also the 50th anniversary of Salford as a University, which makes this year’s conference extra special. Once again we have received a tremendous contribution from our postgraduate research community; with over 130 presenters, the conference truly showcases a vibrant PGR community at Salford. These abstracts provide a taster of the research strengths of their works, and provide delegates with a reference point for networking and initiating critical debate. With such wide-ranging topics being showcased, we encourage you to exploit this great opportunity to engage with researchers working in different subject areas to your own. To meet global challenges, high impact research inevitably requires interdisciplinary collaboration. This is recognised by all major research funders. Therefore engaging with the work of others and forging collaborations across subject areas is an essential skill for the next generation of researchers