Gravel Placement in Horizontal Wells

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper describes a new gravel packing technique for extended-reach open-hole horizontal completions. The method enables gravel packing of long horizontal completions without excessive Beta-wave placement pressure.The physical characteristics of gravel packing horizontal wells have been studied intensively in the past few years. The Alpha-and Beta-wave model has been developed to predict the pattern of sand deposition in the well during the gravel pack operation.The Beta-wave (return gravel wave) placement pressure is the main factor in determining the maximum length of a horizontal gravel pack. This pressure is limited by the requirement to install the gravel pack without exceeding formation fracture pressure, which could result in loss of control of the gravel pack and adverse effects on well productivity.To address the Beta-wave pressure limitation, a new technique has been developed and operationally verified in field installations in the North Sea. The technique uses a special valve, or series of valves, in the inner washpipe that automatically operate to re-direct return fluid flow into the washpipe during placement of the Beta-wave. The valve eliminates the need for the return fluid to travel down the length of the screen to enter through the end of the washpipe. This prevents the accumulation of friction pressure in the screen/washpipe annulus as the Beta-wave propagates from the toe to the heel in the open-hole horizontal section of the well. Strategic placement of these valves in the washpipe string regulates the friction pressure applied against the formation below the fracture limit. Effective design and placement of the valves in the string are made possible with the aid of computational models. The new method essentially eliminates the Beta-wave pressure as a limiting factor in gravel packing extended lateral completions, and makes extended gravel packs possible that would not have been feasible using conventional methods. This paper will describe the concept, discuss the verification-testing program used to validate the theory and review actual field operations that have been performed using this technique.

Section: Spe 71668mentioning

confidence: 91%

Beta-Wave Pressure Control Enables Extended-Reach Horizontal Gravel Packs

Coronado

Corbett

2001

“…It calculates the gravel transport rate, alpha-wave building time, beta-wave placement time, and the total pack time for a given fluid return ratio and slurry pump rate. 7 It estimates the treating pressure as a function of pump rate, gravel size, and mix ratio using dune height as a parameter when clear brine is used as the carrier fluid. The calculations are used to avoid fracturing the formation and to estimate the pack efficiency.…”

Section: Gravel Pack Designmentioning

confidence: 99%

World's First Gravel-Packed Uniform Inflow Control Completion

Augustine

Mathis

Nguyen

et al. 2006

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Etame oil field, offshore Gabon, West Africa, has been producing since September 2002. The Etame oil reservoir is an oval-shaped, low-relief structure with a moderate aquifer drive. In order to maximize ultimate field recovery, the ET-6H well was drilled with a horizontal lateral positioned to traverse the reservoir near the structural crest and to be within the Upper Gamba sandstone throughout its length. The Gamba sandstone averages 45 ft in thickness and overlies a significant angular unconformity. The subcropping Dentaleaged sandstones and interbedded shales below this unconformity have dips up to 12 degrees. The oil column of approximately 170 ft extends below this unconformity. Previous wells in the field were completed using open-hole horizontal gravel packs (OHGPs) and have experienced excellent sand control performance. However, OHGPs offer no protection against early water breakthrough. The Gamba sand averages 30% porosity with a permeability range of 1 to 3 darcies. The Dentale sands are much more variable, with porosities of 18-30% and a permeability range of 50-1000 md. Thus, if a portion of the lateral is situated immediately above a high permeability Dentale sand, the well will be at risk of early water breakthrough and subsequent reduced recovery if it is completed with a standard OHGP.

“…As a result an alpha-wave deposits in the lower part of the wellbore with an equilibrium height dictated by gravel and fluid properties as well as local velocities. 2 Once the alpha-wave reaches the toe of the well, the beta-wave is initiated. The gravel is then deposited on top of the alpha-wave tracing back all the way to the top of the screen and somewhat beyond in the blank pipe section.…”

Section: Introductionmentioning

confidence: 99%

An Alternative Method of Dealing With Pressure: Friction Reducer for Water Packing of Long Horizontal Open Holes in Low-Fracturing-Gradient Environments

Baser-Langenau

Shenoy

Gadiyar

et al. 2009

Water packing is the most commonly used gravel packing technique for openhole horizontal completions. With this technique, the packing of a horizontal well occurs through two sequential events, called the α-wave and the β-wave. Because the carrier fluid is diverted into and must travel through the narrow annulus between the screen base-pipe and the wash-pipe all the way to the toe, pressure builds up steadily during the β-wave as the packing proceeds from toe to heel, due to high friction pressures in that annulus. This rise in pressure may result in exceeding the fracturing pressure of the reservoir, which in turn causes a premature screenout and an incomplete gravel pack. This is a well known problem, which in the past often limited the horizontal well length that can be gravel packed in many deepwater developments, due to narrow operating window. Today, various solutions are available to solve this problem, including mechanical solutions that create a short cut for fluid returns, and the use of light weight gravel which allows pumping at lower rates without having to worry about gravel settling in the work string but still have a α-wave height that will cover the screens.In this paper, we present an alternative method of dealing with the pressure rise during the β-wave, reducing the friction pressures through addition of a friction reducer to brine carrier fluid. We first detail the laboratory scale experiments used for screening of many additives considered, including laboratory scale friction pressure measurements, compatibility with high density brines, gravel settling, formation and gravel pack damage. We then discuss the results from full scale friction tests conducted in pipe and annular geometries, using the best candidate friction reducer selected based on laboratory tests. The results indicate that a drag reduction of 40 to 50% is attained with an environmentally friendly friction reducer, with retained permeability of about 90%, and with minimal to no impact on gravel settling and thus α-wave height.