No abstract

In a deviated well in Caspian Sea gas oil ratio (GOR) increased rapidly in 2017. The result was an oil rate decline with several choke backs to manage GOR build-up. After performing two production-logging jobs, it was confirm that 76% of the gas production was coming from four upper perforations. The main objective was to perform a Gas Shut off (GSO) treatment in two stages to reduce gas production by squeezing polymer into the formation and setting packers at 59° deviation inside 9-5/8 in. casing for temporarily isolation of middle and lower production sands. Fifteen runs were perform with a tube wire-enabled CT telemetry (CTT) system which consists of a customized bottomhole assembly (BHA) that instantaneously transmits differential pressure, temperature, depth data to surface through a non-intrusive tube wire installed inside the CT. For the first time in the region, a tension, compression and torque (TCT) sub-assembly was deploy to control the entire set/retrieve process with accurate downhole upward/downward forces. CTT technology was a key element to successfully set two Thru Tubing Inflatable Retrievable Packers (TTIRP) by doing casing collar locator (CCL) correlations at tubing end which was 133 m and 228 m (MD) shallower from setting depths. In addition, during second GSO operation, polymer crosslink time was modify based on actual bottomhole temperature recorded with CTT system. Finally, during third GSO treatment placement was improve spotting more GSO system in casing section avoiding further treatments. After successful placement of the GSO system, a drop from 15.5 to 4.5 MMscf/day in gas production was observed along with GOR reduction from 11,000 to 750 MMscf/bbl and oil rate increment from 1.4 to 6.04 Mbpd. Furthermore, after gas reduction operator was able to produce between 1.5 to 2.0 Mbpd from other wells that were choke back based on gas handling capabilities limitations The novelty of using the CTT system and TCT sub-assembly for real-time monitoring of BHA data was proven for not only positioning two TTIRP, modifying polymers crosslink design, placing polymer precisely across target intervals and retrieve two TTIRP that at the end provide direct and positive financial impact for the operator.

Handil is a mature oil and gas field discovered in 1974 and developed since 1975. The field extends on a 40km2 area and includes hundreds of stacked hydrocarbon accumulations. Firstly produced by natural depletion, water injection was then implemented as an improved oil recovery mechanism to sustain the oil production and enhance the waterflooding.. From 1995 to 2007, tertiary recovery mechanism was implemented with gas injection. In 2007, with increasing oil price it has been decided in 2007 to resume EOR opportunities in Handil, an Alkali-Surfactant-Polymer project has been initiated. A pilot project of Chemical EOR Injection had been initiated in 1980-s but had to be suspended few years later due to technical reasons and low oil price. In order to evaluate this EOR method potential, remaining stake evaluation was done with different residual oil saturation measurements (coring, logging, SWTT). First analysis lead to very low oil residual saturation: Gas effect with possible tertiary flooding and fresh water flooding are the main hypotheses to explain these results. A screening of the EOR techniques applicable in Handil ended up with the suggestion to test surfactant polymer injection into a wareflooded reservoir. Therefore as a first step an assessment of residual oil saturation was critical. To properly evaluate the volume at stake it was first essential to determine range of remaining oil saturation into water flooded reservoirs. It has been decided to use two different approaches: a first one via existing wells based on the technique of Single Well Tracer Test (SWTT), the second one being coring of the reservoir nearby the tested area investigated by the SWTT. Both approaches gave similar results. However preparation of a SWTT campaign in a mature field environment was challenging. Facing the importance of the measurement, long preparation time was taken to ensure that residual oil saturation values found are reliable and representative. Due to field maturity where most of existing well integrity is questionable, requirement to perform integrity test of the well candidate was compulsory. A hydraulic test and a mutifinger imaging tubing run were done ending with what was assumed to be the qualification of 4 wells out of 5 initial candidates. Indeed SWTT have been successfully performed into reservoirs accessible via the some qualified existing old producers. However interpretation of the data raised several questions. Consequently it has been decided to investigate whether tracers had been placed into the right reservoir. Investigation was performed using Water Flow Log technique that helped understanding where the tracers went and also the well integrity status behind casing. Three (3) Water Flow Logs have been run into the wells with uncertainties. Combination of the hydraulic test, multiimaging tool and water flow log, helped discarding 1 (one) out the 4 (four) wells due to unexpected communications behind casing. Thanks to these operations EOR project could go forward with reliable remaining oil saturation measurement, key value for project design, and with a certified qualifying procedure to be applied on any future existing old well susceptible to be used by the project.

Summary In a deviated well in the Caspian Sea, the gas/oil ratio (GOR) increased rapidly in 2017. The result was an oil rate decline with several choke backs to manage GOR buildup. After performing two production-logging jobs, it was confirmed that 76% of the gas production was coming from four upper perforations. The main objective was to perform a gas shutoff (GSO) treatment in two stages to reduce gas production by squeezing polymer into the formation and setting packers at a 59° deviation inside a 9⅝-in. casing for temporary isolation of the middle and lower production sands. Fifteen runs were performed with a tube wire-enabled coiled tubing (CT) telemetry (CTT) system that consists of a customized bottomhole assembly (BHA) that instantaneously transmits differential pressure (DP), temperature, and depth data to the surface through a nonintrusive tube wire installed inside the CT. For the first time in the region, a tension, compression, and torque (TCT) subassembly was deployed to control the entire setting/retrieval process with accurate downhole upward/downward forces. CTT technology was a key element to successfully set two through-tubing inflatable retrievable packers (TTIRPs) by performing casing collar locator correlations at the tubing end, which was 133 and 228 m [measured depth (MD)] shallower from the setting depths. In addition, during the second GSO operation, the GSO gel system crosslink time was modified on the basis of the actual bottomhole temperature (BHT) recorded with the CTT system. Finally, during the third GSO operation, treatment placement was improved, spotting more GSO gel system inside the casing section and avoiding further treatments. After successful placement of the GSO gel system, a drop from 15.5 to 4.5 MMscf/D in gas production was observed (GOR reduction from 11,000 to 750 MMscf/bbl) with an oil rate increment from 1.4 to 6.04 Mbbl/D. Furthermore, after the gas reduction, the operator was able to produce between 1.5 and 2.0 Mbbl/D from other wells that were choked back on the basis of gas handling capabilities limitations. In the short term, GOR reduction sustained at 3,000 MMscf/bbl and 3.0 Mbb/D oil rate. The novelty of using the CTT system and TCT subassembly for real-time monitoring of BHA data proved to be beneficial for positioning two TTIRP, modifying GSO gel system design, placing it precisely across target intervals, and retrieving two TTIRPs that in the end provided direct and positive financial impact for the operator.

The Handil field is a giant mature oil field in Indonesia. It has been producing since 1975 with current recovery factor for oil is 49% and gas is 57%. Cumulatively, oil had been produced around 855 MMstb and gas around 1.68 Tcf. Now, from this field, oil is being produced at 20,000 bopd, gas at 75 mmscfd and water at 130,000 bwpd. One of the feasible and economic ways to recover the remaining oil at this late stage of field production is by doing a Light Workover technique. This technique aims to change the well status without pulling out the existing completion. This technique is considered the optimum way to maintain the field production performance up to now. One of Light Workover technique is to do re-completion by inserting smaller completion inside existing completion. An innovative spool adapter was utilized to be able to run smaller completion and sit above existing wellhead. Hence, from three (3) depleted gas wells that were converted into oil wells, all wells are still producing and economically had been paid out the intervention cost. This technique is considered applicable for a mature oil field where some gas wells had been depleted and oil layers are exist.