Minimising or eliminating completely the flaring of hydrocarbons during well clean-up and early production testing is an increasing challenge for the oil and gas industry and an important issue for Karachaganak Petroleum Operating b.v. (KPO). KPO operates the giant Karachaganak gas-condensate carbonate reservoir located in north-western Kazakhstan. To improve reservoir management and field recovery, KPO drills long horizontal wells and then stimulates them with acid. KPO has used a variety of different acid stimulation techniques, progressing from simple acid washes to high rate matrix acid treatments and hydraulic fracturing with gelled acid. With the advent of mechanical downhole diversion equipment, KPO can now perform Multi-Stage Selective Acid Stimulation treatments. However, as the complexity of the stimulation techniques has increased, so has the volume of fluid injected into the wells, most of which is recovered to surface during the subsequent clean-up and well testing. The processing facilities at Karachaganak are not designed to handle large quantities of water. A traditional approach to dealing with this problem would be to flare all the produced fluids from the wells until an acceptable water-cut of 1% is achieved. KPO recognised that it had to adopt a different methodology in order to reduce the volume of hydrocarbons flared during well clean-ups and testing. A new approach to well clean-ups was sought that would be capable of efficiently separating the fluids and measuring the flow-rates from high productivity wells and would: Reduce or eliminate flaring. Reduce the environmental impact of well clean-up operations. Dispose of unwanted fluids in a safe and environmentally friendly manner. Recover additional hydrocarbons that would otherwise be flared. This paper describes the evolution and application of a new approach to performing well testing, clean-up and water separation and treatment in the Karachaganak field. It describes the methodology, challenges and strategies that were adopted to manage the liquids produced during the clean-up and early testing of new Karachaganak wells. It focuses on the value brought to both the environment and the field by the deployment of an advanced, integrated 3 Phase High Pressure Separator (3P-HPS) spread with associated water treatment concept.
The objective of this article is to demonstrate recent results of a water cut measurement campaign in the Karachaganak oil and gas condensate field. Historical, inaccurate well water cut assessment was due to the limitations of well test facilities which led to uncertainty in short- and long-term production forecasts. Several approaches were conducted to eliminate uncertainties in water cut measurements and to evaluate and define adequate tools to use for future water cut analysis. The use of a mobile sampling flow loop installed at the well head, where turbulent multiphase flow is guaranteed, was a safe and reliable approach to measure the water cut of the producing low and high productivity wells. Sampling and analyzing the fluid at the well site at various operating well head pressures, frequently and for long periods of time, resulted in better understanding of water cut dependence with changes in drawdown. In addition to the use of sampling on site, the optical sensor (OS) technology was a trial tested on two wells along with the sampling flow loop to confirm the accuracy of the technology. The existing test separators were not designed to handle high water rates; moreover, due to the complexity of the produced hydrocarbon, multiphase flowmeters are not able to accurately measure the correct fluid phase contribution and, as a result, inaccurately estimate phase rates. The OS tool demonstrated accurate real-time water cut readings in the liquid phase, when compared with the flow loop samples, as long as a turbulent flow is guaranteed during measurement. Thus, this technology can be considered as an accurate tool for water cut measurements. The possibility of temporary and permanent installation of the optical sensor tool at the well site or test lines is under evaluation. The current field development focuses on improved recovery from the oil rim which is above a weak aquifer. In the historically developed areas of the field this aquifer is separated from the hydrocarbons by impermeable shale and therefore water production has been minimal. Current and future development requires the drilling of new wells in areas not protected by barriers; this has led to a number of recent wells having a relatively early water breakthrough. As a result of accurate water cut measurements, unallocated water in the field was well defined and led to better control of water producing wells to maintain stability of process facilities. This application confirmed the limitations and low level of accuracy of the existing well test separators. The successful campaign to improve water cut assessment was critical to update and re-evaluate production wells’ operating philosophy, reservoir management, and the future development strategy of the carbonate reservoir.
Сокращение выбросов углеводородов в атмосферу: применение комплексного решения по сепарации технологической жидкости и пластовой воды из скважинного флюида при освоении скважин на месторождении Карачаганак, Республика Казахстан Индира Казиева (КПО), Тамер Саада, Питер Хатсон (SPE/КПО/Би Джи Групп), Симоне Андреа Фрау, Энцо Вильянте (КПО/Эни), Лео Донохью, Разия Шектебаева, Арман Избассов (КПО) Авторское право 2014 г., Общество инженеров нефтегазовой промышленности Этот доклад был подготовлен для презентации на Ежегодной Каспийской технической конференции и выставке SPE, 12 -14 ноября, 2014, Астана, Казахстан.Данный доклад был выбран для проведения презентации Программным комитетом SPE по результатам экспертизы информации, содержащейся в представленном авторами реферате. Экспертиза содержания доклада Обществом инженеров нефтегазовой промышленности не выполнялась, и внесение исправлений и изменений является обязанностью авторов. Материал в том виде, в котором он представлен, не обязательно отражает точку зрения SPE, его должностных лиц или участников. Электронное копирование, распространение или хранение любой части данного доклада без предварительного письменного согласия SPE запрещается. Разрешение на воспроизведение в печатном виде распространяется только на реферат объемом не более 300 слов; при этом копировать иллюстрации не разрешается. Реферат должен содержать явно выраженную ссылку на авторское право SPE.
The objective of this paper is to demonstrate multiple application of multi-energy gamma ray venture type multiphase flowmeter (MPFM) trial campaign in Karachaganak gas condensate giant carbonate field, operated by KPO B.V. The results of MPFM that was included into surface well test spread, to verify its performance, was compared against portable test separator and plant production testing facilities (control separator, flowmeters) and manual sampling results. MPFM from other vendors historically failed to deliver accurate production measurement mainly due to complexity of reservoir fluid in Karachaganak field. To ensure the MPFM considers this complexity, PVT samples were taken to provide laboratory data for PVT model of the MPFM to ensure sufficient quality of PVT data and compare against PVT model inside MPFM. First application of MPFM was during clean-up of the well prior handover well to production. Using MPFM helped to improve the quality during data acquisition. This information was critical for the well to be accepted by processing facility it is hooked-up to and to define optimal operating regime. Validation of BS&W, GOR and rates in unstable (foaming, carry over) and transient phase of production using MPFM has shown practical advantages. Another application was for water sampling loops to measure water cut and production rates. KPO has had challenges with inaccurate water cut measurement due to the limitations of existing test separators. A recent approach of performing fluid sampling (sampling loop) at the well head proved to be reliable source of measurements. In addition, the MPFM in combination with the test separator has been used to further improve the quality of the measurements of each phase. The third MPFM application had been with high gas-volume-fraction (HGVF) pumps, that helped to produce from low reservoir pressure, low GOR and high water cut wells. The operational range of HGVF pump was limited to maximum 75-80% of gas-volume-fraction (GVF). MPFM measures GVF in real-time to ensure HGVF pump operates in optimum operational range by managing the surface flow conditions. With current limitations of test separators in Karachaganak field and due to complexity of the gas-condensate fluid, the use of MPFM brings additional quality in the measurements (rates, water cut and GOR) which is crucial for field production optimization, reservoir management and short and long term forecasting.
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