This paper presents the results of design and field execution of sand control completions for Raven High Pressure High Temperature (HPHT) gas field in Egypt. The reservoir contains stacked channel formation sands, that require sand control completions. The completions design is complicated due to combination of sand control and HPHT environment where industry has limited experience. The selected completions type was an Open Hole Gravel Pack (OHGP) with a pre-drilled liner. A series of lab testing has been conducted to design and qualify completions fluids. The lab test program included formation damage tests, shale stability tests under dynamic and static conditions, materials and fluids compatibility tests and others. The downhole completions hardware was specifically designed to allow effective displacement from oil based mud to completion brine fluid with subsequent gravel pack placement. The circulating gravel pack placement technique was selected using Cesium Formate brine as a gravel carrier fluid. The field installation campaign of the selected completions method is currently underway with 4 wells already successfully being completed. All completed wells demonstrated excellent well performance results with very low completions skin. The well flow-back and test results exceeded expectations, indicating the entire reservoir sand was contributing to flow, demonstrated greater than predicted Productivity Index (PI) with minimal skin damage. Sand control integrity was achieved with full gravel pack efficiency.

The Clair Ridge field development is located in the UK Continental Shelf, 142 miles north of mainland Scotland. This is the second phase of the Clair Field Development involving a subsea pre-drilling campaign and programmed long term well suspensions prior to new platform arrival. Two pre-drilled horizontal wells have been successfully completed with downhole sand screens in a geologically challenging environment, and suspended with cleaned-up hydrocarbons across the reservoir until the wells can be tied back to the platform in 2016. The reservoir drilling and completion design strategy was complicated due to the reservoir section being a naturally fractured sandstone alongside high permeability and weak matrix intervals susceptible to sand production. This presented several challenges to the team: the high risk of losses whilst drilling the reservoir with the probable use of large volumes of lost circulation materials (LCM), the risk of damage to the natural fractures or high permeability zones impacting subsequent well productivity, the need for down hole sand control completions, the ability to run these across a reservoir section containing large amounts of sized calcium carbonate LCM materials and also the mitigation of screen plugging from filter cake and LCM during well start-up. The downhole completion hardware was specifically designed to allow efficient placement of chemical breaker to dissolve LCM and filter cake to reduce the risk of sand screen plugging. The importance of minimising screen plugging and formation damage was also dictated by long term suspension of the pre-drilled wells required for start-up of a new offshore platform. This paper details the reservoir sand control completion design philosophy, the drilling and completion fluid system design and assurance testing in readiness for the technical challenges to be faced and the overall operational practices used in the field execution. The well flow-back and test results exceeded expectations, indicating good flowing length, greater than predicted Productivity Index (PI) and absence of skin damage, which creates significant benefit for the Clair Ridge project.

Shunt tube deployed Open Hole Gravel Pack (OHGP) completions have been installed in the industry for about 25 years and have become widely recognized as a very reliable sand control completion technique. Some of these shunt tube gravel pack operations, are pumped with no positive surface treating pressure for a long duration of the packing operation. This paper will discuss in detail the system hydraulics and shunt tube packing process in these types of operation. The paper will review the surface and down hole gauge pumping data from a suite of shunt tube gravel packs which were pumped for sustained periods with no positive surface treating pressure. It will identify and discuss gravel packing signatures and trends that are unique to these types of operations including detailed analysis of down hole gauge data. Additionally, the paper will discuss the challenges and potential issues that can occur when executing this type of gravel pack and potential mitigation measures. Shunt tube deployed OHGP systems are designed to function in wells with small fluid weight to fracture pressure windows and as such are pumped at low rate with a viscous carrier fluid. Consequently, many of these gravel packs are pumped with no positive pump pressure as the positive u-tube pressure of the additional hydrostatic weight of the slurry in the work string is higher than the overall friction pressure in the system. This effect can have a significant impact on the job execution in several ways if not fully understood and appropriately incorporated into the pumping plan. The potential impacts which are discussed in the paper, include: Inability to monitor the downhole packing process and bottom hole circulating pressure which can result in fracturing the formation while still with no positive surface pressure. Apparent increases and decreases to the return rate which can potentially be misinterpreted as losses or gains and subsequently drive detrimental changes to the execution plan including early termination of the operation and large reductions in pump rate. Stalling of the down hole packing process when there is inadequate pressure differential to drive flow through the shunt tubes The mechanics of pumping shunt tube OHGPs without positive surface pressure has not been previously studied in depth or documented. Given the challenges with real time pumping diagnostics and post job analysis of the packing process of these jobs and the potential for misinterpretation of the data, the paper will provide a comprehensive review of this issue that can be used as a basis for designing and executed future operations.