ERIC ROP RESERVOIR ENGINEER KENGEN, KENYA

Transcription

1 ERIC ROP RESERVOIR ENGINEER KENGEN, KENYA

2 INVESTIGATION OF THE POSSIBILITY OF USING HYDRAULIC FRACTURING AS A METHOD OF ENHANCING WELL PRODUCTIVITY AND INJECTIVITY IN OLKARIA, KENYA.

3 INTRODUCTION Geothermal prospect areas in Kenya Located within the Kenyan Rift system 1st power plant of 45 MWe ( ) Field size about 204 km 2 Divided into seven (7) sectors Total installed capacity 212 Mwe Present assessment-additional 900 Mwe Implementation phase of 280 mwe

4 LOCATION OF OLKARIA GEOTHERMAL AREA

5 OLKARIA DIVIDED TO 7 SECTORS

6 OLKARIA 280MW PROJECT Total of 66 wells drilled; both injection and production Costs 2.7 Million Dollars in Olkaria per well Average power per well of 7 Mwe Target average was 5 Mwe Some wells are dry or poor producers but with temps above 300 c 0 Tight with poor permeability Failure to strike natural fractures

7 WELL PRODUCTVITY AND INJECTIVITY IMPROVEMENT Three possible ways of improving well permeability: 1. Hydraulic fracturing-pumping water propant mix at high pressures to break rocks 2. Explosive fracturing use of explosives to break rock 3. High energy gas fracturing-propellants burn more slowly and push fractures some distance from the well bore

8 HYDRAULIC FRACTURING First treatment was pumped in 1947 on a gas well operated by Pan American Petroleum Corporation in the Hugoton field To compare with acidizing successfully used well stimulation method in petroleum industry Involves pumping propant water mix at high pressures enough to fracture formation

9 HYDRAULIC FRACTURING CONTD Propant not commonly used in geothermal applications expensive Improves permeability on damaged wells during drilling Increases injectivity index or productivity index Economic viability of EGS projects critically dependant on the method

10 HYDRAULIC FRACTURING JOB DESIGN LAYOUT

11 WELL STIMULATION IN OLKARIA Step pumping done at 1000 lpm,1300 lpm,1600 lpm and 1900 lpm Improves well permeability by reducing skin effect Pumping rates too low to cause appreciable fracturing Enables the evaluation of well injection capacities and permeability

12 PRESSURE BUILD IN OW-915

13 PRESSURE BUILD IN OW-907A

14 OLKARIA PUMPING TEST RESULTS sudden decrease in pressure after 2 1/2 hrs pumping in OW- 915 sudden decrease in pressure after 7 1/2 hrs pumping in OW- 907A Indication of improved permeability Possibly through reduced well bore damage or Formation fracturing

15 CASE STUDY 1: WAYANG WINDU GEOTHERMAL FIELD Injection test done on 4 wells, WWQ-2 WWQ-3, WWA-2 and WWQ-4 pumping rate was increased in 8 steps from 22 l/s to 54 l/s Steam production improved by 100% from 4 kg/s up to 8.5 kg/s in WWQ-2 Steam production improved by 50% from 4 kg/s up to 6 kg/s in WWA-2 Open fracture created in WWQ-3, no fracture in WWQ-4 due to insufficient pressure

16 PRODUCTION TEST RESULTS FOR WWQ-2

17 CASE STUDY 2: GEOTHERMAL WELL STIMULATION IN THE US Done under DOE Geothermal Reservoir Well Stimulation Program (GRWSP) in experiments were conducted Experiment 1- Reverse flow technique used Resulted in 5 times productivity improvement Experiment 2-convetional hydraulic fracture treatment used 50000kg/hr flow rate achieved Experiment 3 & 4-planar- type hydraulic fracture

18 CASE STUDY 2: GEOTHERMAL WELL STIMULATION IN THE US Achieved production improvement of 114% yielding commercial flow of 90 tonnes/hour Experiment 5- nonproductive, 70 m isolated using an experimental high temperature Otis packer with EDPM elastomeric elements. Post-stimulation tests indicated a fracture had been successfully created single fracture 100 m high and about 160 m long created Experiment 6 -HCl etching treatment was done

19 CASE STUDY 2: GEOTHERMAL WELL STIMULATION IN THE US No productivity improvement was achieved Experiment 7- high viscosity fracturing fluid with sintered bauxite proppant Tests indicated highly conductive fracture was achieved with a length of over 100 m. Unfortunately poor productivity achieved

20 CASE STUDY 2: GEOTHERMAL WELL STIMULATION IN THE US Fracture treatments in Raft River and those in Baca succeeded in getting significant production from previously non-productive intervals In fractured systems, new fractures are created or reopened they run parallel to existing permeable fractures and do not connect to them Medium producing wells should also be tested

21 CASE STUDY 3: HYDRAULIC FRACTURING AT THE EUROPEAN HDR/HFR SITE Performed successfully in the Hdr/fr test site in Soultz-SOUS-FORÊTS (France) Underground heat exchanger formed by a hydraulically stimulated fracture system. High injection rates and pressure created large fracture systems in the crystalline basement between 3 and 5 km depth Injectivity and productivity of the boreholes GPK1 and GPK2 enhanced by more than 100%

22 EGS DEVELOPMENT CYCLE

23 CONCLUSION Hydraulic fracturing greatly improves well permeability Well injectivity and productivity index can improve Success of EGS systems depends on hydraulic fracturing technique Investment in hydraulic fracturing should be encouraged by the stakeholders to improve the technology Drilling projects costs can be greatly reduced

24 Thank you for your attention