spe papers_well deliverability

Download Spe Papers_well Deliverability

Post on 21-Oct-2015

213 views

Category:

Documents

25 download

Embed Size (px)

TRANSCRIPT

NotesNov-09NOTES:The papers listed here have been obtained by search SPE and IPTC papers post 2005 on the SPE's OnePetroThe papers relating to reservoir engineering have been catergorised for inclusion on the reservoirengineering.org.uk websiteThe affiiations searched were;

Total No PapersReservoir Engineering RelatedBP551175Shell575279Chevron482238ConocoPhillips19168Marathon5537Total255129Schlumberger1130563Imperial College, London9553Heriot Watt University, Edinburgh 235175(Anywhere in Article)Total35691717Total number of papers published post 2005 =10,00035% of papers published categorised

Well DeliverabilityOrganisationSourcePaper No.ChapterSectionSubjectTitleAuthorAbstractSHELLSPE101038Well DeliverabilityAcid TreatmentsCase StudyA High-Success-Rate Acid Stimulation CampaignA Case HistoryN. Al-Araimi, SPE, Brunei Shell Petroleum Co. Sdn. Bhd. and L. Jin, SPE, Shell Intl. E&PAbstract A successful acid stimulation campaign was conducted in 2004 in Brunei Shell Petroleum (BSP). This paper discusses what have been done differently best practices and learning. What is different in this campaign from previous ones? Detailed design Detailed well-by-well review for first round candidate selection. Fundamental data collection (well data pressure formation fluids - water and oil mineralogy data and lab tests). Data management system allowing for quick access to well production history data. A design tool (Stim2001) for detailed candidate selection damage diagnosis fluid system selection and job design. QA/QC and compatibility tests aiming to obtain high success rate. In Brunei Shell a self-raising rig (BIMA) with a coil-tubing unit on board is used to overcome the limitations due to weather. A combined pumping procedure (coiled tubing and bull-heading) was implemented to best-fit individual well condition. Close cooperation among different parties (Well services Subsurface technology teams Operation services and Service providers etc.) 6000 bpdoe of initial gain was achieved by this campaign in Brunei with high success rate (no failure on single well was recorded). Confidence level of acid stimulation in Shell Asia Pacific region has been elevated through this stimulation campaign. Lessons learnt and best practices established will be passed to future campaigns. We would like share our belief that acidization is still a good means for stimulating well productivity but it has to be carried our properly. Introduction Stimulating of existing oil and gas producing wells and of new wells is one of the means to maximizing production potentials without requiring extra facilities and drilling new wells. A synergized stimulation process among a geographical region would benefit each individual asset in the organizational structure that was introduced to the region in Late 2003. Acid stimulation in Shell Asia Pacific region has not been very active compared to other regions. The cause of the relatively low stimulation activity varies. Major factors that limit the stimulation activity include: Various success rate Fewer non-stimulated wells from which stimulation candidates could be selected Operational difficulties (as conventional offshore CT operations normally it is time consuming especially rigging time crane usage boat/vessel availabilities and weather down time) Cost structure: coil tubing cost overruns overall stimulation cost Weather conditions make stimulation operation in conflict with other operations in a limited weather window. And added cost due to waiting for weather time. Contractual limitations An initiative of conducting stimulation campaigns in the region was started in early 2004. It was hoped that under the new business structure some syndication among the region during the stimulation campaign would overcome some of the difficulties listed above and benefit each operation unit (OU) and asset. In Asia Pacific region various reservoir types exist. In this paper we will discuss an acid stimulation campaign in high permeability oil bearing sand stone reservoirs in Brunei.TOTALSPE107760Well DeliverabilityAcid TreatmentsERWAcid Stimulation of Extended Reach Wells: Lessons Learnt From N'Kossa FieldJ.M. Mazel and H. Poitrenaud, Total E&P, and P. MBouyou, Total E&P CongoAbstract NKossa is an offshore field located 60 km west of the coasts of Congo in water depths of 170 m. The field is producing light sweet oil from an Albian age reservoir buried between 3100m and 3400m TVD. In order to access reserves located in the southernmost compartments of the reservoir Extended Reach Drilling (ERD) was implemented. Six ERD wells have been drilled to date with lateral extensions close to 6500 m leading to total depths sometimes in excess of 8600m. In addition to the challenges pertaining to the drilling itself the completion also carried its own ones as the formation would require effective acid-stimulation (not only an acid wash) to reach the desired levels of productivity. Stimulation of long intervals and how to ensure full coverage of treatments is a recurrent topic of debate several approaches have been discussed in the literature. In the particular case of NKossa this issue was not only rendered difficult by the length of the perforated intervals (up to 1200m) but also derived from the combination of lithology and permeability contrasts existing in the formation: indeed the reservoir is an alternation of rather tight carbonates (with permeabilities as low as 1 mD) and porous sandstones (which permabilities sometimes reach up to 400mD). The contrast in permeability is unfavorable as the high permeability layers are often encountered at the heel of the drains. Finally the reservoir temperature is 150C (300F) leading to the need for retarded acid systems. Building on the experience acquired from the successive treatments performed on NKossa the methodology and treatment design fluids and diversion have been continuously evolved. The treatments currently involves two phases: An injectivity initiation is performed via Coiled-Tubing creating an artificial thief zone at the toe of the well; then a massive treatment based on emulsified acid and ball-sealer diversion is bullheaded from a stimulation vessel. This paper will discuss design considerations and operational aspects of the acid treatments performed of these ERD wells. We will discuss some of the observations made and present lessons learnt from such treatments. Introduction Located 60 Km offshore from the Congolese coast the NKossa field was discovered in 1984 and put on production in 1996. The current installation includes two wellhead platforms a floating production facility and two hydrocarbons storage floating facilities (one for oil one for LPG). The water depth varies between 150 m to 300 m in the field. Gas and water injection are used for pressure support in the field. The general set-up is showed on fig 1. The reservoir is of Albian age (Senji formation) and is located between 3100 m and 3400 m in TVD; it consists in a succession of carbonated layers and sandstones sometimes silts. The carbonates occur as silto-sandy calcites or and silty dolomites. The calcites are usually of relatively low permeability: 1 to 50 mD and the dolomites have better petrophysical properties with porosities between 15 to 27% and permeabilities between 10 and 100 mD. The natural fracturing is poor the production is from the matrix porosity. The sandstones are fine to very fine with porosities values between 8 and 20% and permeability between 50 and 200 mD sometimes up to 400mD. The sandstone mineralogy can vary from relatively clean to quite carbonated as the carbonate content can often vary between 10 to 30%. Fig 2 gives an illustration of poro-perm data. The bottom hole temperature (BHT) encountered on the wells discussed in the article is 150C. The hydrocarbon quality encountered in the reservoir varies with the depth from a light sweet oil at the base of the reservoir to condensate gas at the top. The need to access the southernmost compartment of the reservoir from the existing facilities lead to the drilling of wells with significant lateral extension (ERD) (see fig 3) and due to the layered nature of the reservoir the drains usually intercept the layers initially at 70 and then levels-off to horizontal or sub-horizontal (88 up to 92); faulting can lead the drain to intercept twice some of the flow-units. Need for stimulation / Rationale As we saw in the previous paragraph the architecture of the NKossa-South wells as ERDs is directly deriving from the important distance between the production platform and the southern compartment of the NKossa field. The drain intercepts the reservoir initially with a high slant and lands horizontally with lengths varying from 600 to 1500m.SCHLUMBERGERIPTC12368Well DeliverabilityAcid TreatmentsProduction OptimisationOptimizing Well Productivity by Controlling Acid Dissolution Pattern During Matrix Acidizing of Carbonate ReservoirsF.F. Chang, SPE, and M. Abbad, SchlumbergerAbstract The chemical nature of carbonate rocks makes acidizing an effective matrix stimulation technique. Acid dissolves carbonates at high reaction rate to create flow channels (wormholes"). The high reaction rate often needs to be reduced to allow wormholes to penetrate deep into the reservoir hence extending the effective wellbore drainage radius. The wormholes created by a retarded acid are deep but thin. During production the flux through the thin wormholes can be so high that high pressure gradient occurs. Therefore the optimized wormhole geometry should be functions of reservoir properties such as permeability and pressure as well as fluid types such as oil or gas. To generate wormholes of various diameters and penetration depths different acid types and volumes have to be used. Acidizing for optimized productivity requires first determining what is desired