Summary The productive formation in the Kern River field is a sequence of sands designated as the Kern River series. These fine to very coarse sands, each averaging 60 ft (18.3 m) in thickness, are separated by silt and clay interbeds. They are steam-displaced sequentially from the bottom up, one zone at a time. Since steam drive became a viable recovery technique in the early 1960's, all Kern River field steamdrive design and planning was based on the use of a reservoir temperature of 85 to 90°F (29 to 32°C). It was recognized that zones immediately above a previously displaced interval eventually will become heated by the zone below through heat conduction. To a lesser degree, this also occurs in zones below the active drive. With sufficient preheating, very thin sands, previously calculated to be uneconomical and scheduled to be deferred in favor of thicker sands, have proved very productive. The preheating of thicker sands also has resulted in significantly higher production rates than the non heated equivalent sands. This paper discusses the numerical modeling work completed to evaluate the effects of preheating. Field results, including temperature surveys and production data, also are presented to substantiate the theoretical work and prove that preheating effects are an important consideration in a steamdrive operation. Introduction The Kern River field is a large, shallow, heavy-oil deposit located 5 miles (8 km) northeast of Bakersfield, CA. The reservoir is a sequence of up to seven sands designated as the Kern River series. These sands are separated by silt and clay interbeds. Both reservoir and fluid characteristics are very favorable for steamflood methods. The unconsolidated sands have high permeabilities of 1 to 5 darcies and porosities of 28 to 33 %. The average oil viscosity and reservoir temperature are 4,000 cp (4 Pa · s) and 85°F (29°C).
Summary. An infill well program involving 574 wells in previously steamflooded idle reservoirs proved to be economical and increased recovery in some areas from 50 to 58%. These wells were recompleted to zones under active steam drive and showed similar recovery increases in addition to acceleration of reserves. These increases in recovery were attained without additional fuel. Introduction The Kern River field is a large, shallow, heavy-oil deposit located 5 miles [8 km] northeast of Bakersfield, CA. The productive formation is a sequence of sands called the productive formation is a sequence of sands called the Kern River series. The structure is a simple homocline, dipping southwest at 5 deg. [0.09 rad]. The updip sands pinch out, and downdip is bounded by an oil/water contact. These fine-to-very-coarse sands, averaging 60 ft [18.3 m] in thickness, are separated by silt and clay interbeds. The unconsolidated sands have high permeabilities of 1 to 5 darcies and porosities of 28 to 33 %. The average oil viscosity and reservoir temperature are 4,000 cp and 85 deg. F [4 Pa.s and 29 deg. C], although viscosities vary between sands from 2,000 to 40,000 cp [2 to 40 Pa.s]. Texaco Inc.'s Kern River field steamflood involved more than 3,640 producing wells and 1,875 injection wells before infill drilling. The field had been developed on 2 1/2-acre [10 100-m2] five-spot patterns. Up to seven sands are swept, one at a time, usually beginning in the lowest sand. These sands range in depth from 300 ft [91.4 m] in the northeast section of the field to 1,200 ft [366 m] in the southwest. The reported Kern River steamflood oil recovery ranges from 42 to 73% of presteam oil in place (OIP), with an average of 50% a generally place (OIP), with an average of 50% a generally accepted recovery efficiency. We have completed steamfloods in 1,500 pattern sands. Some of the techniques for improving steamflood recovery were summarized by Bursell. They include infill wells, partial or limited perforation of producers, variable steam quality and rate, injection diverting, crossflooding, and injector-to-producer conversion. Before infill wells were drilled, numerical simulation work indicated several attractive benefits from infill wells:recovery increases from 50 to 60% of OIP even with well spacing as small as 0.625 acre [2530 m2],possible similar recovery increase from the 1,500 completed and idle pattern sands, andaccelerated recovery and fuel pattern sands, andaccelerated recovery and fuel reduction. These results have been proved. The following review of four projects will compare theoretical to actual results. The 574-infill-well program was unusual in that most of the wells were first completed in idle sands and were subsequently perforated in upper active steamfloods and the well spacing was reduced to only 0.625 acre [2530 m2] per well. The patterns went from 1.25- to 0.625-acre [5060- to 25 30-m2] well spacing by conversion of a 2 1/2 -acre [10 100-m2] five-spot into a 2 1/2-acre [10 100-m2] nine-spot pattern. 1970 Canfield Project The 1970 Canfield project covers 148 acres [599×103 m2] in the updip portion of the Kern River field, as shown in Fig. 1. A cross section through the project (Fig. 2) shows the steamflood intervals. Table 1 shows reservoir properties. Steam injection in the first displacement sand, Sand R1, began in July 1970. Injection was ended at the steamflood economic limit in Sept. 1977. Fig. 3 shows project performance history. Cumulative steamflood oil recovery performance history. Cumulative steamflood oil recovery from the project was 147,000 STB [23 400 stock-tank m3] per pattern, or 57% of the predisplacement OIP, as shown in Table 2. In Feb, 1978, the project was recompleted upward to Sand R. Conduction heating from the Sand R1 displacement raised Sand R temperature from 85 to 165 and 92 deg. F [29 to 74 and 33 deg. C] at the base and top of Sand R, respectively (Fig. 4). Previous work 4 reported the beneficial effects of this preheating. Steam injection in Sand R was terminated in the 55 patterns during the period from Oct. 1982 to June 1984. Again, injection was ended in these patterns at the steamflood economic limit. Steamflood oil recovery was 97,200 STB [15 450 stock-tank m3] per pattern, or 49%, as shown in Table 2. During this same 1982–84 period, recompletion and injection into Sand K (above Sand R) was started. Concurrently, 80 infill wells were drilled and initially completed in the idle Sand R1. As shown in Fig. 5, these wells were drilled at midpoints of the pattern boundaries. The average production rates for these infill wells are shown in Fig. 6. SPERE P. 243
From October 1973 to June 1976 a caustic steamfloodpilot test projectwas operatad in the Kern River Field of California. The test was conductedin nine adjscent five-spot patternsand utilized Sodium Hydroxideas an additive to the injected steam.The purpose of this paper :[sto present and discuss the operationand rasults of the pilot project. Initial researchand planning processesare descrtbed in addition to comparison of the pilot productionresponsewith other similar patterns in the same area of the field.Tracer and testing programswere initiated in the later stages of the pilot to provide additiGzaldata for analysis of the projecc response. This informationIs presented along with discussionswhich Referencesand illustrationsat end of paper describe the bchavf.or and movement of the Ssdium Hydroxide through the reservotr.From the results of this pilot, recommendat
SPE Member Abstract Since the early 1960's, steamflooding has been completed in 1,600 five-spot 2-1/2 acre (10,000 m2) pattern zones in the Kern River Field. The data from 61 completed projects (averaging 25.8 patterns per project) and 91 cored postflood zones has been used to develop a correlation to predict oil recovery for a given gross sand thickness, oil viscosity, and initial oil saturation. This correlation to predict oil recovery is based on the injection and operating strategies in past use, and changes that have been made in those strategies may result in higher recoveries. In several Projects, average pattern size 4.0 acres (16,000 m2) and 50 feet (15 m) thickness, initial injection rates of 500 BWPD (3.3 m3/hr) were sustained past steam breakthrough. These initial past steam breakthrough. These initial injection rates may have been too high and perhaps should have been reduced at steam perhaps should have been reduced at steam breakthrough. Introduction The Kern River Field 1-12 is a large, shallow, heavy-oil deposit located five miles (8 km) northeast of Bakersfield, California. The productive formation is a sequence of sands designated as the Kern River Series. The structure is a simple homocline, dipping southwest at 5 degrees. The updip sands pinch-out and downdip is bounded by an oil-water contact. These fine to very coarse sands, each averaging 60 feet (18.3 m) in thickness, are separated by silt and clay interbeds. The unconsolidated sands have high permeabilities of 1 to 5 darcies and porosities of 28% to 33%. The average oil viscosity and reservoir temperature are 7,000 cp (7 Pa's) and 85 degrees F (29 degrees C), although viscosities vary between sands from 1,000 cp (1 Pa) to 40,000 cp (40 Pa's). In addition to the viscosity variation, sand thickness and pre-steamflood oil saturation range from zero to 200 feet (61.0 m) and 65%, respectively. Up to seven sands are swept, usually beginning in the lowest sand. These sands range in depth from 300 feet (91.4 m) to 1,200 feet (366 m). Seven thousand pattern-zones will ultimately be steamflooded. For reserve and performance predictions, numerical simulation would be very costly because of the wide range of reservoir parameters in the large number of remaining parameters in the large number of remaining pattern-zones. The problem then was to pattern-zones. The problem then was to develop predictive tools using the significant amount of postflood core and completed project data. Therefore, reservoir data was assembled for 61 completed projects and 91 cored postflood zones. This data was large enough postflood zones. This data was large enough to prepare correlation curves to predict oil recovery for a given gross sand thickness, oil viscosity, and initial oil saturation. To put the correlation in proper perspective, some discussion is needed perspective, some discussion is needed explaining past steam injection strategies and what period in the thermal EOR process the correlation represents. STEAM INJECTION RATES Prior to 1983, selection of initial injection rates for the 70% quality steam was based on pattern area or bulk volume 1. For patterns with less than 80 feet (24.4 m) sand patterns with less than 80 feet (24.4 m) sand thickness, 130 BWPD/acre (59.1 nm/s) was specified. P. 49
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.