The URL can be used to link to this page

Home My WebLink About2018 Schrader Bluff Oil Pool#► rym eni March 29, 2019 VIA HAND DELIVERY Commissioner Jessie Chmielowski Alaska Oil and Gas Conservation Commission 333 West 7th Avenue, Suite 100 Anchorage, Alaska 99501 Re: 2018 Annual Reservoir Surveillance Report Nikaitchuq Schrader Bluff Oil Pool Nikaitchuq Unit, North Slope Alaska Dear Commissioner Chmielowski: eni us operating enl us operating co. inc. 3800 Centerpoint Dr., Sulte 300 Anchorage, AK 99503 — U.S.A. Tel. 907-865-3300 Fax 907-865-3380 RECEIVED MAR 2 9 2019 AQGGC 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, 7 -� W� � Robert Province Manager — Land, Public Relations & Alaska Representative Enclosures: 2018 Annual Reservoir Surveillance Report Schrader Bluff Pool — Nikaitchuq Field us operating 2018 Annual Reservoir Surveillance Report Schrader Bluff Pool Nikaitchuq Field Page I i Eni Petroleum — Alaska Development Table of Contents 1. 2018 Development Activity Summary...................................................................................................3 2. Reservoir Pressure Surveys for the Nikaitchuq Schrader Bluff Pool.....................................................6 3. Pool Allocation Factors during the Year 2018.....................................................................................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. 2018 Development Activity Summary For the year 2018, the drilling activity has been focused on carrying out the activities for the exploratory well NNO1 in the Harrison Bay Block Unit 6423, located north of the Nikaitchuq Unit area. The Nikaitchuq Development pattern, as proposed, will be completed upon termination of the exploratory well. In addition to the drilling of NN01 well, a series of workovers and pump upgrades have been carried out to maintain the production of the field during 2018 as shown in Table 1 below: Well Name Well Type WO Completion Date Drilling Path OP12-01 Oil Producer 01/23/2018 Oliktok Point OP17-02 Oil Producer 04/02/2018 Oliktok Point 01310-09 Oil Producer 04/15/2018 Oliktok Point OP22-WW03 Water well 05/17/2018 Oliktok Point OP18-08 Oil Producer 11/27/2018 Oliktok Point OP23- WW02 Water Well 12/25/2018 Oliktok Point SP21-NW1 Oil Producer 10/23/2018 Spy Island SP04-SE4 Oil Producer 09/23/2018 Spy Island SP08-N7 Oil Producer 10/30/2018 Spy Island SP05-FN7 Oil Producer 12/02/2018 Spy Island Table 1. 2018 Well Workover summary for Nikaitchuq Field Figure 1 below shows the completed well paths and the OA reservoir, for the Nikaitchuq Unit through December 2018: Page 13 Eni Petroleum—Alaska Development X88000 Nikaitchuq Development Pattern - Dec 2018 492890 +32«7C EMU 590986 512000 518880 --29986 g 14 R S T $ 9 ffi 116 � } f 2 3 eP7S-nYll] �� E to •� h ilr 1 SP38.48T 5 5P35 ra t SWIi 8 a * P14.83 tDPW DB w � i — a j 4 I � e 'W742 �p V 7h'F.z Ods OPI 0 C PO ~ OP1 Y 0111.0 nlxiar� w�a e Pu ifl I I 09ktvk P990 j 6 2000 4000 BOOR `-JWOR �C.'_.1 5lIe1{r 188899 .. „ 498860 r --64900 508099 512900 5169W T~ 526960 iSchrader Bluff ESASand -DVvelcp^_ rb Figure 1. Nikaitchua 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 2018 is 55 wells (not including the dual lateral well paths) as shown in Table 2 below: Urr = VUKtoK romt aeveiopment patn (onshore) SID = Spy Island development path (offshore) Table 2. Total well count for Nikaitchug Development Waterflood has been the main drive for oil production in the field and its response has been positive through the years. As seen on the field water injection profile, some oil production rate reduction has occurred due to ESP / completion failures in some of the wells, as shown below: Weil Name Date Planned Activity (2009) Activity up to date (December 2018) OPP SID Total OPP SID Total a, Injector 8 OP22-WW03 12 20 8 11/27/2018 13 21 CL Producer 11 10/23/2018 15 26 11 Electrical failure 18 29 3 Disposal 1 Tubing Hole 1 2 1 1 2 Water Source 1 3 1 0 j 3 3 0 j 3 Total 1 23 28 51 23 32 55 Dual Lateral Well Paths 8 9 17 Urr = VUKtoK romt aeveiopment patn (onshore) SID = Spy Island development path (offshore) Table 2. Total well count for Nikaitchug Development Waterflood has been the main drive for oil production in the field and its response has been positive through the years. As seen on the field water injection profile, some oil production rate reduction has occurred due to ESP / completion failures in some of the wells, as shown below: Weil Name Date RWO lob description OP12-01 01/23/2018 ESP Pump upgrade OP17-02 04/02/2018 ESP Pump upgrade OP10-09 04/15/2018 ESP Pump upgrade OP22-WW03 05/17/2018 Electrical failure OP18-08 11/27/2018 Tubing hole OP23-WW02 12/25/2018 Electrical failure SP21-NWI 10/23/2018 Electrical Failure SP04-SE4 09/23/2018 Electrical failure SP08-N7 10/30/2018 Tubing hole SP05-FN7 12/02/2018 Tubing Hole Page 15 Eni Petroleum — Alaska Development AA aA A A DA Ss t 60,000 ---.—...--- — 40.x00 scow %000 38•M KOM 96.000 52,000 90,000 ? i34,000 n,0W r ti 921000 444,000 30,M 42,000 WM 26.000 36.00e 1 r ° r ,1t 0 24.080 r '34,000 32,OW �.r° h' p a 22,000 a0 t, ti 20.000 a L 28.000- }} kiE 244 .i:°tl �, 60060 20, I� db S 38,000 , �Q00 16,000 i 10-000 14,000 .: v 10 om InjeCti[ n 8 m0 s,aaaGma :ice—QilRate + 6,000 4'W0 .. - - _ 7. -. _ _ _ .. _ _ _ - _ - 0 r, t c t i 2 3 Figure 2. Nikaitchuq Field Production and Events summary 2015-2018 (workover events in yellow) 2. Reservoir Pressure Surveys for the Nikaitchuq Schrader Bluff Pool Continuous reservoir pressure monitoring activities were executed by controlling intake BHP's as shown in Figures 2a & 2b for OPP and SID, respectively. On those plots we illustrate how the 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 wells has been stable in 2018, ranging from 400-650 psi, with the only exceptions due to failed ESPs/tubing leaks in the wells before being workovered (see Figure 2a). Bottom hole pressure for SID wells have been between 350-1100 psi. In October 2018, all SID wells were shut down until December 2018 during the SID pipeline workover activities. Page 16 En! Petroleum —Alaska Development Monthly and cumulative Voidage Replacement Ratios are monitored to understand whether 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 2018 as shown in Figure 3. OPP BHP at Depth of Heel 1950 e 1756 - — --- - — - 1550 1350 e. d 1150 x m 950 750 550 350--- axl —4Pf.2.-01.—i3N7-02• OP1643---v+-0P05-06- OPOR-04 --- OP03-05 —.rPa-07 (]P7,9- M --. -9P10-09 RP09-Si - OP14-53 Figure 2a. Intake BHP measurements in 2018 for active wells at OPP Page 17 Eni Petroleum —Alaska Development 2300 2100 1900 1700 1500 a x 1100 700 S00 300 s: BHP @ Heel X C �i SP16-FN3—SP10-FNS —SPO$ -N7 —SP31-W7 SM-NW1—SP04-SE5 SP;'8 FiM . .SM—WS---SP24-M----SM"N7 —SP27441 —SP23-N3 SPl2.5E3 sP18-F 5 SPSO•Wi—SP33-W3 SP31-W7 O —SP01-SE7 —SP22,FNI Figure 2b. Intake BHP measurements in 2018 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 En! Petroleum —Alaska Development O —5111-FN6 —SI13-FP14 — idh-58 ]dlr-E8 M-18 Nei 1 ".r r4 1[it=ts .q.. Ai: Sep,18 Ott 18 NW,13 I++ Figure 2c. Wellhead pressure measurements in 2018 for injectors at OPP 1000 I 9011 800 700 600 a. 500 400 300 200 100 0 —SI07-SE4 —5111-FN6 —SI13-FP14 —SI14-N6 —SI17-SEZ SII9--FN2 —SI20-N4 —51;5-N2 - 5126-Ntil2 —5129-52 5132-W2 5134•W6 5135-W4 yam: Figure 2d. Wellhead pressure measurements in 2018 for injectors at SID Page 19 Eni Petroleum —Alaska Development Nikaitchuq Pressure Map Up to December 2018 Figure 3. Pressure map of Nikaitchug Field as of December 2018 Page 110 Eni Petroleum —Alaska Development 3. Pool Allocation Factors during the Year 2018 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 2018, 1,021 well tests were performed. Measurements were performed on a multiphase meter. Daily theoretical production per well is calculated based on the last valid well test and the amount of time that the 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 first of the month test results. Subsequently, the allocation factor will be recalculated on the fifth of the month using the new valid test measured on the fifth. Looking at the monthly level data, our AVOCET Manager Production software sums up the allocated volumes from each time period between valid well tests. (Minutes on production/1440 minutes/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. Subsequently, daily allocated production is assigned to each well by multiplying its theoretical daily production by the daily allocation factor. The average allocation factor for 2018 has been 1.1373 1.2 1.18 1.16 1.14 1.12 1.1 1.08 1.06 1.04 1.02 1 January 1,1483 February 1.1494 March 1.1432 April 1.1530 May 1.1480 June 1.1406 July 1.1372 August 1.1328 September 1.1178 October 1.1652 November 1.0045 December 1.1216 Figure 4. Average field allocation factor trend for 2018 Page 1 11 En! Petroleum—Alaska Development 4. Reservoir Management Summary For 2018, the Nikaitchuq OA reservoir monitoring activities have supported the aiming to 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 (Sill-FN6, S119-FN2, 5113-FN4, 5125-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. Resman tracers deployed in some of the Nikaitchuq oil producers are now expired and are no longer useful for hydrocarbon inflow evaluations. Three OPP injectors (0106-05, 0107-04 & 0111-01) and two SID injectors (5114-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 : 12 Eni Petroleum —Alaska Development Nikaitchuq Meld - Resen,�anr Monitoring Map Schrader Bluff OA Sand • Developmenr 1'.ax•f ��r.T� eni Figure 5. Nikaitchu ma showing wells with Resman Tracerco tracers and QTS Fibers Page 113 Eni Petroleum —Alaska Development 4.2 Voidage Balance by Month of Produced Fluids and Injected Fluids on a Standard and Reservoir Volume Basis with Yearly and Cumulative Volumes Approximately 6.0 million barrels of oil produced from the Nikaitchuq field during 2018, at an average daily production of 16,533 bopd. Injected volumes of water during this time was approximately 17.1 million barrels at an average daily rate of 46,830 bwpd. Table 3 below summarizes the entire voidage replacement for the Nikaitchuq field in 2018. 0.80 0.60 0.40 0.20 4.00 Jan -18 Feb -18 Mar -18 Apr -18 May -18 Jun -18 Ju�-18 Aug -18 Selz -18 Oct -18 Nov -18 Dec -18 Table 3. 2018 Nikaitchuo Field Monthly Production/Infection Volumes and Vofda a Replacement Ratio graph En! Petroleum -Alaska Development I Page 1 14 Production Injection Monthly Oil Water Gas Water VRR BBL BBL MCF BBL 8BL Jan -18 592,617 825,539 82,699 1,529,390 1.02 Feb -18 543,279 792,766 71,091 1,390,699 0.99 Mar -18 587,956 868,264 1. 77,646 1,545,772 1.01 Apr -1 535,585 820,128 62,903 1,472,299 1.03 May -181 602,650 920,906 74,472 1,521,925 0.95 Jun -18 575,085 895,954 82,282 1,527,912 0.99 Jul -18 572,089 934,358 74,365 1,595,623 1.01 Aug -18 555,913 937,277 72,688 1,615,248 1.03 Sep- 8 487,584 867,218 60,596 1,557,2041 1.1 Oct -181 498,834 894,921 62,089 1,597,722 1.09 N ov-18 196,584 380, 507 14,751 707,023 1.17 Dec -1 285,360 499,2201 29,858 1,032,206 1.25 Total 6,033,536 9,637,058 765,440 1 17,093,023 1.04 0.80 0.60 0.40 0.20 4.00 Jan -18 Feb -18 Mar -18 Apr -18 May -18 Jun -18 Ju�-18 Aug -18 Selz -18 Oct -18 Nov -18 Dec -18 Table 3. 2018 Nikaitchuo Field Monthly Production/Infection Volumes and Vofda a Replacement Ratio graph En! Petroleum -Alaska Development I Page 1 14