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Water production has always afflicted mature fields due to the uneconomical nature of high water cut (WC) wells and the high cost of water management. Rigless coiled tubing (CT) interventions with increasingly articulated operating procedures are the key to a successful water reduction. In the scenario presented in this paper, high technological through tubing water shut off (WSO) for a long horizontal open hole (OH) well in a naturally fractured carbonate reservoir leads the way to new opportunities of production optimization. Engineering phase included sealant fluid re-design: the peculiar well architecture and fracture systems led to the customization of a sealant gel by modifying its rheological properties through laboratory tests, to improve effectiveness of worksite operations. A new ad-hoc procedure was defined, with a new selective pumping and testing technique tailored to each drain fracture. The use of Real-Time Hybrid Coiled Tubing Services (CT with fiber optic system coupled with real time capabilities of an electric cable) made it possible to optimize intervention reliability. Details of the operating procedure are given, with the aim of ensuring a successful outcome of the overall treatment Sealing gels are effective in plugging the formation, but in fractured environments the risk of losing the product before it starts to build viscosity is high. The success of the water shut off job has been obtained by using specific gel with thixotropic properties for an effective placement. In addition, the pumping has been performed in steps, each followed by a pressure test to assess the effectiveness of the plugging. Results are compared to two past interventions with equal scope in the same well: a first one with high volume of gel and an unoptimized pumping technique through CT and a second where a water reactive product was pumped by bullheading. The selective and repetitive approach pumping multiple batches of sealant system with CT stationary in front of a single fracture provided the best results from all three techniques. The real-time bottom hole data reading capability provided by hybrid CT allowed the placement of thru tubing bridge plugs (BP) with high accuracy and confidence with the ability to set electrically, therefore reducing risks related to hydraulic setting tools (i.e. premature setting). This also allows continual pumping during the run in hole (RIH) to clean up the zone prior to setting the BP. The combination of this innovative pumping technique and customization of the sealant fluid made it possible to achieve unprecedented water reduction in the field. The high technology CT supported the operation by providing continuous power and telemetry to the bottom hole assembly (BHA) for real time (RT) downhole diagnostics. Moreover, the operating procedures offer basic guidelines to successfully perform water shut off jobs in any other reservoir independent of its geological nature and structure.
Water production has always afflicted mature fields due to the uneconomical nature of high water cut (WC) wells and the high cost of water management. Rigless coiled tubing (CT) interventions with increasingly articulated operating procedures are the key to a successful water reduction. In the scenario presented in this paper, high technological through tubing water shut off (WSO) for a long horizontal open hole (OH) well in a naturally fractured carbonate reservoir leads the way to new opportunities of production optimization. Engineering phase included sealant fluid re-design: the peculiar well architecture and fracture systems led to the customization of a sealant gel by modifying its rheological properties through laboratory tests, to improve effectiveness of worksite operations. A new ad-hoc procedure was defined, with a new selective pumping and testing technique tailored to each drain fracture. The use of Real-Time Hybrid Coiled Tubing Services (CT with fiber optic system coupled with real time capabilities of an electric cable) made it possible to optimize intervention reliability. Details of the operating procedure are given, with the aim of ensuring a successful outcome of the overall treatment Sealing gels are effective in plugging the formation, but in fractured environments the risk of losing the product before it starts to build viscosity is high. The success of the water shut off job has been obtained by using specific gel with thixotropic properties for an effective placement. In addition, the pumping has been performed in steps, each followed by a pressure test to assess the effectiveness of the plugging. Results are compared to two past interventions with equal scope in the same well: a first one with high volume of gel and an unoptimized pumping technique through CT and a second where a water reactive product was pumped by bullheading. The selective and repetitive approach pumping multiple batches of sealant system with CT stationary in front of a single fracture provided the best results from all three techniques. The real-time bottom hole data reading capability provided by hybrid CT allowed the placement of thru tubing bridge plugs (BP) with high accuracy and confidence with the ability to set electrically, therefore reducing risks related to hydraulic setting tools (i.e. premature setting). This also allows continual pumping during the run in hole (RIH) to clean up the zone prior to setting the BP. The combination of this innovative pumping technique and customization of the sealant fluid made it possible to achieve unprecedented water reduction in the field. The high technology CT supported the operation by providing continuous power and telemetry to the bottom hole assembly (BHA) for real time (RT) downhole diagnostics. Moreover, the operating procedures offer basic guidelines to successfully perform water shut off jobs in any other reservoir independent of its geological nature and structure.
Inflatable packers have been the preferred technique for the selective placement of chemical treatments in a wellbore with Coiled Tubing (CT). Traditionally, these have come with some limitations, such as power supply, Real-Time (RT) positioning, surface control, differential pressure activation, ball drop setting, tension, reciprocating set systems, and the ability to quickly change the tool flow path based on treatment response. This paper discusses the first electrically controlled packer implementation that drastically improved operational efficiency in Iraq. This case relates to a mature field in Iraq where precise selective acidization of vuggy carbonate zones with high permeability contrasts was required. The operation was carried out successfully with an electrically controlled packer suitable for acid that provided real-time downhole insight to improve the decision-making process and a precise, flawless acidizing operation. Additionally, the electric actuation system enabled independent control of the flow path position throughout the operation, allowing fluid injection above or below the element to suit the requirements of the operation as needed. The unique solution provided in this paper confirms the benefits of customizing fiber optic and electric technology with an inflatable packer to accurately place the element and selectively stimulate zones with high permeability contrast. A RT downhole sensor module also provides critical information to ensure the operation is carried out as intended. The particular sensors that helped carry out this operation included the Casing Collar Locator (CCL) and Gamma-Ray (GR) to correlate depth, internal and external temperatures, a load module, and internal and external pressure measurements to precisely position the packer in between two layers of a narrow interval without exceeding either the reservoir frac pressure or the packer element differential pressure. This revolutionary technique was successfully implemented on an injection well, saving more than 24 hours of intervention time and allowing early injection to reduce costs for the customer. The CT Electric Inflatable Packer (EIP) enabled the splitting of the operation into two treatments, above and below the packer, during the same run. The approach to this intervention increased operational efficiency while reducing waste to optimize the overall well intervention cost with RT data. This paper describes how a new versatile EIP technology can improve operational efficiency and reduce non-productive time on various applications, such as selective treatments, multiple selective acidizing of sleeves, clusters, intervals, water shut off with sealant fluids, or chemical sand consolation with resins.
The well (Figure 1) of the case study presented in this paper is an oil producer from carbonate reservoir located in Southern Europe. Reservoir is characterized by a complex fracture network that increases the difficulties of production optimization actions, as for example water shut off interventions. This well is completed with a 4-1/2" liner extending to a 4-1/2" slotted liner inside a 6" open hole (OH). During the production time, the Water Cut (WC) has increased steadily finally reaching 94%, preventing the well from producing naturally. Log acquisition and interpretation, with Production Logging Tool (PLT) and Spectral Noise Logging (SNL), have shown that the water was coming from a fractures network laying behind the liner, to enter the top of the slotted liner despite swellable packers A and B. The lack of accessibility to this fractures network was therefore posing a challenge for an effective placement of a sealant gel.
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