Wyniki wyszukiwania - BazTech

1

Loss and restoration of water coning control - field case history and prediction

Wojtanowicz A., Jin L.

AGH Drilling, Oil, Gas

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2018

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Vol. 35, no. 1

343--360

EN

It is well known that water coning is a difficult-to-solve problem in heavy oil reservoirs with bottom water. A promising solution is offered by the downhole water sink (DWS) technology – a dual well completion technique for water coning control in reservoirs with bottom aquifer. In the field case addressed in this study, a DWS well was installed in a heavy oil reservoir underlined by thin water zone – notorious for severe water coning problem. Initially, the two well’s completions had no separating packer; Later, the well was recompleted with packer and displayed much improved oil productivity and water coning control. However, after accidental shutdown of the bottom (water sink) completion and continuing production from the top (oil pay) completion the well was rapidly watered out and shut down. In this study, the well’s production history is analyzed to better understand dynamics of water coning control with packer-less DWS and the effect of temporary water sink shut-down. The analysis is performed with a radial grid-based simulation model using the reservoir properties and well production data. An adequate history match is achieved by tweaking reservoir properties within their uncertainty range – mostly the relative permeability and capillary pressure curves. The packer-less completion displays steady invasion of water to the top oil completion through the gravel pack with no separating packer. The analysis also confirms detrimental effect of sole temporary shutdown of the water sink (bottom) production that caused rapid buildup of water saturation in the oil pay zone around the well. This work also evaluates possible restoration of oil productivity by putting the well back on production after a dormant period of time (when water cone might subside) and the contribution of the bottom water drive (aquifer strength) to the restored productivity. A 25-year production performance forecast is performed for three scenarios of well’s operation after the water sink completion’s shut-down for one month: (a) no shut-down and continuing production as DWS well; (b) one-month shut down and conversion to a conventional single-completed well; (c) one-month shut down and continuing production as DWS well. The results reveal that the watered-out well could be revived as an oil producer only by restoring its DWS operation [scenario (c)] as the conventional well operation [scenario (b)] would produce only water. Moreover, detrimental effect of temporary water-sink shut down would irreversibly reduce well's productivity by more than 10 percent. It is also shown that stronger aquifer stimulates DWS well productivity improvement of up to 20 percent in case of strong bottom water drive.

2

Improved recovery of heavy oil with bottom water using downhole water sink (DWS) technology

Wojtanowicz A. K., Qin W.

Wiertnictwo, Nafta, Gaz

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2010

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T. 27, z. 1--2

467-484

EN

The paper presents a worldwide survey of heavy oil reservoirs and their production methods. The survey shows that one of the most important problems in heavy oil recovery is the presence of bottom water. Since the mobility of water drastically exceeds that of heavy oil, water breakthrough to oil wells occur very early causing dramatic loss of the wells' productivity due to rapid increase of the water cut. The study captures some the difference between heavy and light oil production in terms of mobility ratio effect, recovery dynamics prior to and after water breakthrough, and water cut control with production rate. The results also show that the controlling water breakthrough to wells in heavy oil is several-fold more important (in terms of well productivity and recovery rate) than that for conventional oil wells. Most of heavy oils with bottom water cannot be economically recovered using "cold" (non-thermal) method and conventional (single completed) wells. In these wells, operational range of production rates with variable water cut is very small comparing to light oils. Thus, heavy-oil wells would promptly (within days) switch from water free production to "all water" production. The paper also summarizes a feasibility study into potential application of downhole water sink (DWS) technology in shallow sand containing very significant deposit of heavy oil. Downhole water sink is a new technique for minimizing water cut in wells producing hydrocarbons from reservoirs with bottom water and strong tendencies to water coning. DWS technology controls water coning by employing a hydrodynamic mechanism of water drainage in-situ below the well's completion. This localized drainage is generated by a second completion - downhole water sink - installed at, above, or beneath the oil or gas-water contact. For the purpose of this study a DWS well has been modeled and compared with a conventional well using a commercial reservoir simulator. Results show that DWS technology has great potential to improve recovery in the oil sand with bottom water. All simulated predictions of DWS performance indicate a significant improvement of oil production rates and a several-fold increase of recovery factor. Also explained is the physical mechanism of the improvement that is not specific to the reservoir studied but applies to all heavy oil deposits with bottom water problem.

PL

W artykule omówiono rozmieszczenie i wielkość zasobów ciężkiej ropy naftowej na świecie, oraz typowe metody jej eksploatacji, która jest szczególnie trudna przy występowaniu wód podścielających. Trudność spowodowana jest dużą różnicą mobilności wody i ciężkiej ropy, co prowadzi do wczesnego przebicia się wody do otworów i gwałtowny spadek ich produkywności. Prezentowane badania symulacyjne pokazują różnice mechanizmów otworowej produkcji ropy ciężkiej i wyjaśniają dlaczego metody termiczne wydają się jedynym sposobem produkcji i dlaczego te metody także zawodzą w obecności wód podścielających. Omówiono także wyniki badań symulacyjnych użycia technologii otworów z wgłębnym upustem wody do nietermicznej eksploatacji ciężkiej ropy z wodą podścielającą na konkretnym polu naftowym. Wyniki pokazują wielokrotne zwiększenie stopnia sczerpania złoża w okresie 17 lat oraz znaczny wzrost dziennej wydajności otworu. Zidentyfikowano także mechanizm hydrauliczny, który daje otworom z dolnym upustem wody zdecydowaną wyższość nad konwencjonalną technologią w zastosowaniu do ciężkiej ropy z wodą podścielającą.

3

A study of water coning control in oil well by injected barrier and downhole water sink technology

Bekbauov B., Kaltayev A.

Zeszyty Naukowe. Górnictwo / Politechnika Śląska

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2009

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z. 287

19-26

EN

A numerical simulation of heavy oil recovery process developed in this work to investigate the time dependent development and dynamic shape of the water-oil interface around the well producing from a bottom-water-drive homogenous reservoir. The objectives of this study: developing a numerical model demonstrating water coning; placement of a drainage completion under the barrier, and perform a parametric study of a combined gel barrier placement with water drainage; ascertainment of the ability of a horizontal gel barrier to prevent water breakthrough; investigation of the performance of the gel barrier shut off technology associated with the Downhole Water Sink (DWS) technology; investigation the impermeable manmade barrier shut off and DWS methods' impact on the breakthrough time, and the critical rate; investigation of the effect of barrier radial size; demonstration of barrier-drainage system efficiency etc.

PL

Przedstawiono numeryczny model procesu pozyskiwania ropy z jednorodnego złoża z wodą denną. Pozwala on prześledzić zmiany i rozwój granicy woda-ropa wokół otworu eksploatacyjnego. Uzyskane rezultaty potwierdzają przydatność modelu do analizy wpływu zastosowania bariery iniekcyjnej i technologii odwadniania dna otworu (DWS) na ograniczenie tendencji do tworzenia się stożków nawodnieniowych.

4

Down-hole water sink technology for water coning control in wells

Wojtanowicz A.K.

Wiertnictwo, Nafta, Gaz

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2006

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R. 23/1

575-586

EN

Downhole Water Sink (DWS) technology has been developed from a new well completion and production method for enhancing productivity of wells in petroleum reservoirs with bottom water drive and strong tendency to water coning. DWS minimizes water invasion to the well's completion by employing hydrodynamic mechanism of coning control in-situ at the oil-water or gas-water contact. The mechanism is based upon a localized water drainage generated by another well completion (downhole water sink) installed in the aquifer beneath the oil-water or gas-water contact. The paper summarizes the development and state-of-the-art at DWS technology. Presented are results from theoretical studies, physical and numerical experiments, and field projects to date. It is demonstrated that DWS could increase recovery and control water production in vertical and horizontal oil wells - with natural flow, downhole pumps or gas lift, and in the gas wells from low-pressure tight gas reservoirs. Although by now DWS has been used in reservoirs with bottom water, theoretically the technology is also applicable in dipping structures with encroaching side-water

PL

Technologię odwadniania dna otworu opracowano na podstawie nowych otworów oraz zastosowanych metod zwiększania produkcji ropy w warunkach silnej tendencji do tworzenia się stożków zawodnieniowych. Przedstawiona metoda ogranicza napływ wody do otworu dzięki kontroli mechanizmu tworzenia się stożków nawodnieniowych na granicy gaz-woda i woda-gaz. Mechanizm polega na zlokalizowaniu wycieku wód za pomocą innego udostępnianego otworu odwierconego poniżej strefy kontaktu ropa-woda lub gaz-woda. W artykule podsumowano rozwój i obecny stan technologii odwodnieniowej. Przedstawiono wyniki prac teoretycznych badawczych, doświadczeń fizycznych i numerycznych oraz bieżących projektów. Wykazano, że zastosowanie technologii odwodnieniowej przyczynia się do poprawy wydobycia i kontroli produkcji wody w pionowych i horyzontalnych otworach naftowych, przy wykorzystaniu mechanizmu naturalnego przepływu, pomp wgłębnych i airliftu; w przypadku otworów gazowych - do niskociśnieniowych szczelnych złóż gazu. Chociaż technologię odwodnieniową stosuje się w przypadku złóż z wodą denną, teoretycznie technologia ta może być zastosowana także w przypadku wód okalających