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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Chirag Field, located offshore in the Caspian Sea of Azerbaijan, uses permanent downhole gauges to record continuous pressure and temperature in the active producers. Bottom-hole pressure data is used extensively to understand interwell communication and reservoir properties, but bottomhole temperature data had seen little use. However, we now find that flowing bottom-hole temperature detects interwell communication -with interference delay times consistent with pressure transient analysis -and can be used to estimate interwell permeability. To explain our observations we propose that FBHT responds to the impact of pressure changes. The principal result is a change in the producing GOR, which in turn depends on the speed and magnitude at which a pressure change is transmitted through the reservoir. The effect is pronounced when flowing pressures are below bubble-point and compounded by Chirag's steeply dipping reservoir having gradients versus depth in saturation, temperature, bubble-point, and solution-GOR. Field examples highlight the strong cause-effect relationship between producer-injector and producer-producer pairs, giving evidence of a new interference testing method with wide potential application. Chirag FieldThe Chirag Field in Azerbaijan (Fig-1 and 2) is located offshore in the Caspian Sea. It is part of the Azeri-Chirag-Guneshli (ACG) development and the principal production zone is the Middle Pliocene Pereriv sand. There are currently ten producers and six peripheral water injectors active in Chirag. Production, exported through the Baku-Tblisi-Ceyhan (BTC) pipeline, is 140 Mstb/D with 900 GOR (scf/stb) and less than 1% watercut; water injection is 140 Mbw/D. The structure is an elongated anticline with dips of up to 45 degrees, an overall hydrocarbon column height of up to 1000 meters, and an average stratigraphic thickness of 130 meters in the Pereriv. The two most permeable intervals, the Pereriv-B and Pereriv-D, have a total thickness of 80 meters with 20% porosity and 200 md permeability.

Sand production remains a key technical challenge in the ACG (Azeri-Chirag-Gunashli) field as the target formation is comprised of weakly consolidated sandstone. Although sand control completions (such as open hole gravel pack) are used to limit sand entry into the well, water breakthrough, increased fines production, high flux across completed intervals amongst other factors may negatively impact on their effectiveness as well as stability of reservoir rocks, resulting in high sand production, consequently requiring choking back of wells. This, at times, leads to significant production deferrals, which are attributed to the impact on entire production system: completion, wellbore, chokes, flow lines and production vessels. Therefore, improving techniques and developing technologies for downhole diagnostic and remediation to restore production will be of value throughout the ACG field life. An effective remediation requires an understanding of the sand entry points. Over the last 24 months, BP has developed a new real-time technology solution that employs novel signal processing techniques using Distributed Acoustic Sensing (DAS) systems to detect sand entry points along the wellbore during production. The technology solution has been employed to the interpretation of over 30 conducted surveys to identify sand entry zones in real time. In some instances, the results have also been used to inform targeted remediation using expandable patches. This paper summarizes the results from some of the DAS sand detection surveillance data acquired (in integration with other relevant dataset) and its use in remediation of compromised completion intervals. The authors will also share examples of drawdown optimization and risk management of wells with sand production based on acquired DAS data. This paper will cover a few examples of DAS survey data acquired both for wells with pre-installed fibre (25 wells) and those without it where the technology was deployed via wireline intervention (5 wells). The application of DAS technology in ACG has provided substantial value to date (both in terms of production and safety) and has much more value to be realized as the technology continues to mature.

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Integration of field surveillance data is important to understand reservoir description and dynamics particularly for waterflood schemes in which injector-producer connectivity is necessary for the expected oil recovery improvement. This paper shows an example of integration of DTS with other surveillance data to optimise the placement of a water injector in the complex northern part of the Deep Water Gunashli (DWG) field, Azerbaijan. Some of the dynamic data responses and trends were inconclusive but Distributed Temperature Sensor (DTS) evidence from two wells were instrumental in showing good pressure communication within the complex north-flank area, and water injection in the lower sands only.