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Home My WebLink About2017 Schrader Bluff Oil Poolcn� us ®perrafing 2ni March 21, 2018 VIA HAND DELIVERY Commissioner Cathy Foerster Alaska Oil and Gas Conservation Commission 333 West 7"' Avenue, Suite 100 Anchorage, Alaska 99501 Re: 2017 Annual Reservoir Surveillance Report Nikaitchuq Schrader Bluff Oil Pool Nikaitchuq Unit, North Slope Alaska Dear Commissioner Foerster: eni us operating co. Inc. 3800 Centerpoint Dr., Suite 300 Anchorage, AK 99503 - U.S.A. Tel. 907-865-3300 Fax 907-865-3380 MAR 21 2018 AOGCC The Alaska Oil and Gas Conservation Commission approved pool rules for the Schrader Bluff oil pool within the Nikaitchuq Unit as Conservation Order 639. Rule number 12 of the order requires the filing of annual surveillance report, which is enclosed hereto. Should you have any questions, require additional information or wish to schedule a meeting to discuss the report, please contact me. Sincerely, Ro ert Province Manager — Land, Public Relations & Alaska Representative Enclosures: 2017 Annual Reservoir Surveillance Report Schrader Bluff Pool — Nikaitchuq Field RECEIVED MAR 21 2018 #, A®GCC 2nn ass operrMc ng 2017 Annual Reservoir Surveillance Report Schrader Bluff Pool Nikaitchuq Field Eni Petroleum—Alaska Development Page I i Table of Contents 1. 2017 Development Activity Summary...................................................................................................3 2. Reservoir Pressure Surveys in the Nikaitchuq Schrader Bluff Pool.......................................................6 3. Pool Allocation Factors over the Year 2017........................................................................................11 4. Reservoir Management Summary.......................................................................................................12 4.1 Voidage Balance by Month of Produced Fluids and Injected Fluids on a Standard and Reservoir Volume Basis with Yearly and Cumulative Volumes...................................................................................14 Page I ii Eni Petroleum—Alaska Development 1. 2017 Development Activity Summary The remaining development drilling at SID (Spy Island Drilling site) has been placed on hold for rig preparation regarding the extended reach drilling exploratory well NNO1 in Harrison Bay Block Unit 6423 Unit, North of the Nikaitchuq Unit area. The drilling plan is to continue development drilling activity for the Nikaitchuq field after the culmination of the exploratory well and with improved economic conditions. Table 1 below summarizes the well work over activities performed during the year 2017: Well Name Well Type WO Completion Date Drilling Path SP22-FN1 Oil Producer 4/15/2017 Spy Island SP12-SE3 Oil Producer 3/17/2017 Spy Island SP28-NW3 Oil Producer 3/27/2017 Spy Island SP16-FN3 Oil Producer 4/4/2017 Spy Island SP22-FN1 Oil Producer 4/15/2017 Spy Island OP16-03 Oil Producer 11/25/2017 Oliktok Point OP03-P05 Oil Producer 12/29/2017 Oliktok Point Table 1. 2017 Well Workover summary for Nikaitchug Field Page 13 Eni Petroleum—Alaska Development Figure 1 below shows the completed well paths and the OA reservoir, in the Nikaitchuq Unit through December 2017: Nikaitchuq Development Pattern - Dec 2017 Y, .I. Yr � ,6.D. w.D ` r t `\ �s OF 0 200 4000 6ODD 8NO I000GR , aso6o .mom am am svw mm mmo Schrader Bluff OA Sand-Deveb ment DeY Blpnabe eni Figure 1. Nikaitchug Development Map. Green = producer, Blue = infector, = Dual lateral producer, Purple = N Sand Appraisal well, dashed lines (----) planned development wells. Page 14 Eni Petroleum —Alaska Development The total well count in 2009 was 51 wells. The total well count at the end of 2017 was 55 wells (not including the dual lateral well paths) and is summarized in Table 2 below: OPP = Oliktok point development path (onshore) SID =Spy Island Development path (offshore) Table 2. Total well count for Nikaitchua Development Oil production in the Nikaitchuq field has been and continues to respond positively to waterflood. The field water injection profile below shows how the continuous water injection positively impacts oil production, during the year 2017. Drop in oil production occurred due to ESP / completion failures in some of the wells (see below). Well Name Date SP12-SE3 June 2017 OP03-P05 July 2017 SP05-FN7 August 2017 OP16-03 November 2017 Page 15 Eni Petroleum — Alaska Development Planned Activity (2009) Activity up to date (December 2017) OPP SID Total OPP SID Total a Injector 8 12 20 8 13 21 CL F Producer 11 15 26 11 18 29 a Disposal 1 1 2 1 1 2 3 Water Source 3 0 3 3 0 3 Total 23 28 51 23 32 55 Dual Lateral Well Paths 8 9 17 OPP = Oliktok point development path (onshore) SID =Spy Island Development path (offshore) Table 2. Total well count for Nikaitchua Development Oil production in the Nikaitchuq field has been and continues to respond positively to waterflood. The field water injection profile below shows how the continuous water injection positively impacts oil production, during the year 2017. Drop in oil production occurred due to ESP / completion failures in some of the wells (see below). Well Name Date SP12-SE3 June 2017 OP03-P05 July 2017 SP05-FN7 August 2017 OP16-03 November 2017 Page 15 Eni Petroleum — Alaska Development 9 —Inle<don �Ul Race Figure 2. Nikaitchuq Field Production and Events summary 2015-2017 with 2017 WO (see yellow triangles) Reservoir Pressure Surveys in the Nikaitchuq Schrader Bluff Pool Similar to previous years, reservoir pressure monitoring activities were executed by controlling intake BHP's as shown in Figures 2a & 2b for OPP and SID, respectively. These plots show how intake pressures have been gradually stepped down while Eni monitored signs of sand production, rising water cuts (WC), gas -oil ratios (GOR) and balancing voidage across all sectors in the field. Intake pressure at OPP goes from 450-850 psi (See Figure 2a). However, the pressure spread is larger at SID where some ESPs have reached lift capacity (See Figure 2c). Larger capacity ESP's are planned for future workover opportunities. Monthly and cumulative Voidage Replacement Ratios are monitored to understand whether or not enough water is being injected in the field (See section 4.1). Maps of dynamic pressures are extremely helpful for monitoring activities (see Figure 3). The reservoir pressure measurements were also used to support the Nikaitchuq reservoir model pressure map of 2017 as shown in Figure 3. Page 16 Eni Petroleum—Alaska Development ee imII wraw AA G6 D { Ol�!IMilo i ima ♦ • ♦ ♦ dA C —Inle<don �Ul Race Figure 2. Nikaitchuq Field Production and Events summary 2015-2017 with 2017 WO (see yellow triangles) Reservoir Pressure Surveys in the Nikaitchuq Schrader Bluff Pool Similar to previous years, reservoir pressure monitoring activities were executed by controlling intake BHP's as shown in Figures 2a & 2b for OPP and SID, respectively. These plots show how intake pressures have been gradually stepped down while Eni monitored signs of sand production, rising water cuts (WC), gas -oil ratios (GOR) and balancing voidage across all sectors in the field. Intake pressure at OPP goes from 450-850 psi (See Figure 2a). However, the pressure spread is larger at SID where some ESPs have reached lift capacity (See Figure 2c). Larger capacity ESP's are planned for future workover opportunities. Monthly and cumulative Voidage Replacement Ratios are monitored to understand whether or not enough water is being injected in the field (See section 4.1). Maps of dynamic pressures are extremely helpful for monitoring activities (see Figure 3). The reservoir pressure measurements were also used to support the Nikaitchuq reservoir model pressure map of 2017 as shown in Figure 3. Page 16 Eni Petroleum—Alaska Development imII wraw { Ol�!IMilo i ima .�i��i�iiYli�ii'7�Y3'ai■■li!■� al'f!'lllli� d471■'■Il��ES �� .,,, l�itf l��i1��1�■� ,,, R �i �y71l� �ta►ar:� �el ��1 !!I�!>i�1■�I�iit1Y foil Nikaitchuq Production —Inle<don �Ul Race Figure 2. Nikaitchuq Field Production and Events summary 2015-2017 with 2017 WO (see yellow triangles) Reservoir Pressure Surveys in the Nikaitchuq Schrader Bluff Pool Similar to previous years, reservoir pressure monitoring activities were executed by controlling intake BHP's as shown in Figures 2a & 2b for OPP and SID, respectively. These plots show how intake pressures have been gradually stepped down while Eni monitored signs of sand production, rising water cuts (WC), gas -oil ratios (GOR) and balancing voidage across all sectors in the field. Intake pressure at OPP goes from 450-850 psi (See Figure 2a). However, the pressure spread is larger at SID where some ESPs have reached lift capacity (See Figure 2c). Larger capacity ESP's are planned for future workover opportunities. Monthly and cumulative Voidage Replacement Ratios are monitored to understand whether or not enough water is being injected in the field (See section 4.1). Maps of dynamic pressures are extremely helpful for monitoring activities (see Figure 3). The reservoir pressure measurements were also used to support the Nikaitchuq reservoir model pressure map of 2017 as shown in Figure 3. Page 16 Eni Petroleum—Alaska Development 950 850 750 2 m 650 550 450 350 BHP at Depth of Heel Figure 2a. Intake BHP measurements in year 2017 for active wells at OPP —OP32-01 —OP17-02 —OP16-03 —OPM-06 —OP&04 —OP3-05 —OP4-07 —OPIO-W ---OP10-09 oP451 --OP34-53 Page 17 Eni Petroleum—Alaska Development 1200 1100 1000 900 a 800 6 G_ m 6W 500 400 300 BHP @ Heel Figure 2b. Intake BHP measurements in year 2017 for active wells at SID On the injector side, wellhead pressure limits are defined based on an equivalent gradient of 0.60 psi/ft to avoid injection at pressures that can fracture the reservoir and preserve the wellbore integrity. Page 18 Eni Petroleum—Alaska Development >. 6m Im —Qro6. —0102A3 —dll-01 —011303 -42454 —013P0) -- 0124.. —0112 0 Q J I . . lan 11 1— 1] Mar. 17 Apr 17 MaV'11 May t! Jun 17 Jul, 12 Aug, 12 ", 12 0c112 Nov -12 Dr,11 Figure 2c. Wellhead pressure measurements in year 2017 for injectors at OPP 10m 9m Nm 7m 600 �£ Sm 4m 3m 2m lm —502-SE4 —5111 FN6 —5113F1M —$NO Nfi —SII) SE2 —5114FN2 —$I2SN2 —SQ6NW2 —SR452 —432 W2 5134..6 505 W4 Page 19 Eni Petroleum—Alaska Development Q r- V1 r 111 U I l land) 1..17Mail] Apr17 May 17 May 17 lunl2 Jul17 Aug 17 MP 17 O[I-12 Nov -1] O -12 Figure 2d. Wellhead pressure measurements in year 2017 for injectors at SID Page 19 Eni Petroleum—Alaska Development Figure 3. Pressure map of Nikaitchug Field in 2017 Page 1 10 Eni Petroleum—Alaska Development 3. Pool Allocation Factors over the Year 2017 Production from all wells producing from the Schrader Bluff pool is commingled at the surface into a common production line. Theoretical production for individual wells from the pool is calculated on a daily basis by using well test allocation. Wells are tested, at least twice per month for a minimum of 24 times per year per well. For the year 2017, 998 well tests were performed. Measurements are performed on a multiphase meter. Daily theoretical production for a well is calculated using the last valid well test and the amount of time a well was on production for a given day. For example, if there is a valid well test on the first of the month and another on the fifth of the month, the allocation factor for that well would be calculated on the first through the fourth of the month using the test on the first of the month. Subsequently, the allocation factor will be recalculated on the fifth of the month using the new valid test measured on the fifth. On the monthly level, our AVOCET Manager Production software sums up the allocated volumes from each time period between valid well tests. (Minutes on production/1440 min utes/day)*Daily Rate (stb/d) well test=Theoretical Daily Production) The daily allocation factor for the field is calculated by dividing the actual total production for the day by the sum of the theoretical daily production for each individual well. Daily allocated production is assigned to each well by multiplying its theoretical daily production by the daily allocation factor. The average allocation factor for 2017 has been 1.12 1.1900 1.1700 1.1500 1.1300 1.1100 1.0900 1.0700 1.0500 ,ao°a� `Jaci a�� Qin �aJ ice �o�A oJy� ��ac ��ac ��ac Fie` dee P > P Qtia O` oe e`e January 1.1238 February 1.1223 March 1.1172 April 1.1662 May 1.1200 June 1.1066 July 1.1199 August 1.1060 September 1.1068 October 1.0951 November 1.1179 December 1.1320 Figure 4. Average field allocation factor trend for 2017 Page 111 Eni Petroleum —Alaska Development 4. Reservoir Management Summary For the year 2017, the Nikaitchuq OA reservoir monitoring activities have supported the aiming of replenish reservoir energy by replacing the voidage created with water injection and optimizing the field production performance through workover activities. Reservoir energy is evaluated by monitoring surface and bottom -hole pressures. In addition to surface gauges measuring tubing pressures, Nikaitchuq oil producers are equipped with downhole gauges which allow real-time bottom -hole pressure monitoring. Eight injector wells (See Figure 5), four in Spy Island (5111-FN6, 5119-FN2, 5113-FN4, S125 -N2) and four in Oliktok Point (0111-01, OP -12, 0113-03, 0124-08) have also been treated with unique Tracerco tracers in 2015 in order to evaluate the water flow patterns, the breakthrough time and the sweep efficiency of the water injection. During the year 2017 the tracer sampling was carried out regularly. Resman tracers deployed in some of the Nikaitchuq oil producers are now expired and no longer useful for hydrocarbon inflow evaluations. Three OPP injectors (0106-05, 0107-04 & 0111-01) and two SID injectors (SI14-N6 & 5120-N4) are equipped with DTS fiber optics which helps to determine the level of injectivity along the horizontal injection intervals of the injectors. Figure 5 below, shows the Nikaitchuq field map with Resman, Tracerco tracers and the wells injector with DTS fiber optic. Page 112 Eni Petroleum —Alaska Development Figure 5. Nikaitchug map showing wells with Resman, Tracerco tracers and DTS Fibers Page 1 13 En! Petroleum — Alaska Development Nikaitchuq Field - Reservoir Monitoring Map If LEGEND Water njemwith D -S Schrader Bluff OA Send -Development 7 7- eni Figure 5. Nikaitchug map showing wells with Resman, Tracerco tracers and DTS Fibers Page 1 13 En! Petroleum — Alaska Development 4.1 Voidage Balance by Month of Produced Fluids and Injected Fluids on a Standard and Reservoir Volume Basis with Yearly and Cumulative Volumes Approximately 7.5 million barrels of oil was produced from the Nikaitchuq field during the year 2017, at an average daily production of 20,600 bopd. Injected volumes of water during this time was about 16.5 million barrels at an average daily rate of 45,300 bwpd. Table 5 below summarizes the entire voidage replacement for the Nikaitchuq field in 2017. The spikes in the graph are typically associated with Alyeska proration days. 1.15 1.10 - - 1.05 - \ - -f-- 1.00-- 0.95 0.90 - - 0.85 Jan -17 Feb -17 Mar -17 Apr -17 May -17 Jun -17 Jul -17 Aug -17 Sep -17 Oct -17 Nov -17 Dec -17 Table 5. 2017 Nikaitchug Field Monthly Production/Infection Volumes and Voidage Replacement Ratio graph Page 1 14 Eni Petroleum -Alaska Development Production Injection Monthly Oil Water Gas Water VRR BBL BBL MCF BBL BBL Jan -17 632,550 579,882 102,268 1,317,437 1.07 Feb -17 . 575,900 542,891 83,035 1,171,950 1.03 Mar -17 644,176 619,523 93,762 1,226,676 0.95 Apr -17 685,074 625,689 100,235 1,333,360 1.00 May -17 730,625 710,201 100,988 1,409,149 0.96 Jun -17 578,106 1 609,531 80,550 1,313,014 1.09 Jul -17 653,170 731,237 90,954 1,454,488 1.03 Aug -17 632,132 728,788 92,695 1,471,665 1.06 Sep -17 596,018 702,561 90,473 1,414,997 1.07 Oct -17 612,731 747,008 88,334 1,468,356 1.06 Nov -17 570,528 717,726 80,166 1,437,611 1.10 Dec -17 599,796 829,602 86,247 1,530,042 1.05 Total 7,510,806 8,144,639 1,089,707 16,548,745 1.04 1.15 1.10 - - 1.05 - \ - -f-- 1.00-- 0.95 0.90 - - 0.85 Jan -17 Feb -17 Mar -17 Apr -17 May -17 Jun -17 Jul -17 Aug -17 Sep -17 Oct -17 Nov -17 Dec -17 Table 5. 2017 Nikaitchug Field Monthly Production/Infection Volumes and Voidage Replacement Ratio graph Page 1 14 Eni Petroleum -Alaska Development