Many applications for Inflow Control Devices (ICDs) are designed to delay water breakthrough in new wells and for remediating wells shut-in because of water encroachment. The ICDs for carbonate reservoirs typically are combined with wire-wrapped screen (WWS) strainers on 13-ft basepipe. Many wells also have been compartmentalized with swellable packers. Passive inflow control technology has been used extensively in horizontal wells in the Norwegian section of the North Sea and in the Middle East for approximately a decade. This paper discusses first usage of a new tube-type ICD combined with swellable packers to control water in fractured carbonate reservoirs in Asia. Traditionally, horizontal wells in the Poleng field in East Java, Indonesia were completed with slotted liners and struggled with early water breakthrough and high water-cut production. Since highly productive fractures are thought to be the main conduit for water, and slotted liners do not provide control for fluid inflow to the wellbore, resolving high water cut has challenged offshore production significantly.To combat these challenges, a new completion strategy using ICDs and swellable packers for both delaying and minimizing water breakthrough has been developed.Production performance of 5 horizontal wells completed with the ICD/swellable packer concept will be compared to production of 8 wells completed traditionally. This project marks several world firsts in tube-type ICD technology with its first installation in Indonesia.

In many cases, carbonate oil wells are stimulated with open hole acid flush or acid fracturing treatments to increase productivity. Some of the challenges with fracturing stimulation are reservoir related, such as consistently stimulating all targeted intervals and intersecting the natural fracture network. The growth of hydraulic fractures in the vertical direction is difficult to predict, leading to the risk for entering unsought gas or water-bearing formation. Operations can be complex, costly and pose environmental challenges. A multilaterals stimulation technology (MST) has been developed and field tested to be a simple, efficient and more controllable method of stimulation with less environmental impact. The method uses less fluid, reduces the risk of groundwater contamination and eliminates stimulation fluid flowback disposal. This paper discusses the evolution of the technology, leading to the first pilot installation in a horizontal well in the Austin Chalk carbonate reservoir in Texas, during April of 2014. The pilot installation proved the stimulation technology's efficiency by creating 60 laterals, each 40 feet long, in a few hours pumping time. This installation is believed to be a world record for creating 60 laterals in less than 5 hours. The well's production response was significant, and productivity index was increased by 30 times compared to before the stimulation.

The Valhall field has been producing oil for 25 years. The completion strategy of the field has continuously been developed over the years, with cased hole completions with multiple propped fractures as main completion strategy since the mid 1990s. This completion technique was also chosen for the Valhall Flank Project initiated in 2001. The later stages of the project several of the well targets were located on the borders of the field, where the reservoir formation is considerably thinner and has a lower porosity and higher reservoir pressure than in the centre of the field. Using multiple propped fracture completion technique for these targets was not regarded attractive, and to access the reserves in these targets in a cost effective manner it was decided that the optimal design for the "thin pay" targets was a concept with pre-perforated liner in open hole. This paper describes the completion design evolution on Valhall and the considerations made for choice of completion method for the later stages of the Valhall Flank Project. An overview of the swell packer technology, in addition to the specific packer design for Valhall, is given and it is discussed how this technology provided opportunities to isolate several parts of the well if excessive water production occurred. Future applications for swell packer technology are also discussed. Introduction One of the main concerns with the pre-perforated liner concept versus cased hole completions was the lack of zonal isolation. As the well targets on the Valhall Flanks moved further towards the boundaries of the reservoir, it was an increasing risk of excessive water cuts. Means providing opportunity to isolate parts of the well were evaluated, and it was decided to include swell packers in the well S-8, drilled and completed as an open hole dual lateral with pre-perforated liner. The Valhall field The Valhall field is located in the North Sea approximately 290 km offshore southern Norway in 69m of water. The field is located in the southwestern corner of the Norwegian continental shelf. The field was discovered in 1975. Decision to develop the field was made in 1978 and the field started producing in October 1982. The initial development consisted of a 3-platform complex (quarters, drilling and process/compression platforms). In 1996, a fourth platform was added (wellhead platform) to provide additional slots for infill drilling. In 2000, a water injection program from an additional injection platform was approved. To provide efficient access to the flank areas in the North and the South, installation of two new wellhead platforms was approved in 2001. The Valhall field is an over-pressured, under-saturated Upper Cretaceous chalk reservoir and is a NNW-SSE trending anticline. The primary reservoir is the Tor Formation with secondary reservoir from a unit within the Hod Formation. The thickness of the Tor formation varies abruptly ranging from 0 to 80m. The reservoir quality varies considerably with some of the best porosities (up to 50%) and permeability (1 to 10 mD) developed in the thickest areas [1]. Completion design evolution Initial testing at Valhall gave experiences with severe chalk production and casing deformations due to the weakness of the Tor formation. It was apparent that completion design would be a critical factor to successfully produce the field. The completion strategy has continuously been developed over the years with focus on limiting solids production and wellfailures. Details of the completion history can be found in Barkved, O. et al [1]. In short terms, the completion designs have evolved from "Up and Under Fracturing" in the early 80s and "Propped Fractured Gravel packs" in the late 80s, to horizontally drilled wells in the early 90s (Acid Fractured, Acid Matrix Stimulated, Direct Perforated Unstimulated, Cased-off Openhole with inflatable packers). From 1995 to date, the main completion strategy on Valhall has been horizontal cased hole completions with multiple propped fractures. The strategy was developed due to the relatively disappointing performance of the earlier horizontal wells. The multiple propped fracture wells have been completed with 3 to 12 zones, with the number of zones in a well depending principally on the length of reservoir section. The benefits from these completions have been high and sustained rates, typically producing 5,000 to 8,000 BOPD the first year1.

A mature well in a carbonate reservoir in Saudi Arabia was no longer producing and was sidetracked in a workover operation to regain production. This paper describes the usage of swellable packers to isolate a detrimentally water producing fracture encountered during drilling of a 3–7/8" slim hole horizontal in a naturally fractured carbonate reservoir. No means of open hole/slim hole isolation were available prior to the introduction of swellable packers. The packers were successfully run and the well was brought into production at good rates and low water cut. Introduction Natural fracturing is believed to pervade most of the carbonate reservoir due to the brittle nature of these rocks. Today most production wells are drilled as 6–1/8" horizontals and completed with 4–1/2" inflow control devices and open hole packers to delay and manage water production. A number of workover wells are drilled with smaller bit sizes. Consequently, this requires slimmer completion equipment to complete the wells in an optimum manner. Well history Well A was drilled in 1999 as a 6–1/8" open hole high slanted (83°) producer and completed with 7" packer and 4–1/2" tubing. In 2005 the first workover operation was carried out to revive the well that was dead as a result of excessive water production. A window in the 7" liner was cut after decompleting the well and setting a whipstock. A 2,200ft 6–1/8" horizontal sidetrack was drilled in the formation and the well was completed with 7" packer and 4–1/2" tubing. The well was found dead after only one month of production. An acid job was subsequently carried out in an attempt to restart the productive life of the well; however it did not prove successful. Surface and downhole bailer samples were collected and lab tests suggested that an adjacent reservoir was dumping water into the formation. Another workover operation was planned and carried out in 2007. A balanced cement plug was set to abandon the existing lateral. A window in the 7" liner above the reservoir was cut, new 6–1/8" curve section to the top of the formation was drilled, an expandable liner run and set and a 5–1/2" horizontal hole was drilled. If needed, the well would be completed with inflow control devices and open hole packers. After the 5–1/2" shoe was milled out and a negative test was performed after displacing the well to water the well flowed water from the reservoir. A 4–1/2" scab liner was run to isolate the leak in the 5–1/2" liner from 6,598 to 6,720ft. A 3–7/8" open hole was drilled to TD at 8,800ft. A fracture was encountered at 7,586ft with total losses. The remainder of the lateral was drilled with water with no returns. The well was not logged since no caliper was available at that time for this hole size. Slim hole well design Saudi Aramco typically complete the 6–1/8" horizontal open holes in the carbonate reservoirs with inflow control devices to even out the inflow profile along the wellbore and to delay water break-through. Open hole packers are used to compartmentalize the open hole, to isolate fractures and hence manage water production in combination with the inflow control devices. No open hole packer technology was available or approved by Saudi Aramco for such slim holes prior to the introduction of swellable packers; i.e., there was no mechanical means of isolation of fractures or of compartmentalization. The potential consequence was excessive water production and loss of the lateral, resulting in a costly workover operation.

Preventing water or gas breakthrough and equalizing flow is one of the primary challenges of producing from horizontal slimhole wells. This paper will present a "first-of-its-kind" concept in which swellable packers were used to isolate a waterproducing fracture to prevent/delay water/gas breakthrough and equalize flow across a 3-7/8-in. horizontal open hole. The water-producing fracture was encountered during drilling of the slimhole horizontal in a naturally fractured carbonate reservoir. Prior to the introduction of swellable technology to the oilfield, satisfactory solutions for isolation in open hole slimhole wells had not been available. Although swellable technology was new to the area, after careful analysis of the situation, the operator and the service company decided to use four swellable packers to compartmentalize the hole.The completion configuration was successfully run, and the well was brought into production at good rates and with a low water cut.