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1. Overview
Installation of the MxL Induction Heating System in a horizontal well has demonstrated:
robust and durable system, operating from 2001 through 2004, at which time operation ceased due to over temperature in the bunker housing the PCU.
Approximate 10% production decline in heated well very low as compared to adjacent unheated wells.
Modest initial water cut increase then constant compared to adjacent wells
This was accomplished with a tool that heated about 20% of the zone with available power from the grid limited, for the most part, to less than 50% of the system’s power capability.
Third party review has commented favourably on the results.

2. Background
On October 9, 2001 an MxL Induction Heating System was installed in the above referenced well on the Suffield Dieppe Block which had been in production for approximately eight months. The first heated section, Inductor “A”, is 52 m long and commences 25 m beyond the casing shoe then a 27.3 m spacer then a 57 m heater section ”B” followed by a 27.9 m spacer then the last heater section “C” which is 55 m long followed by 510m of unheated hole beyond the tool. The heater is located in the heel of the well and only covers 20% of the production zone.

The Power Conditioning Unit (PCU) was installed in a bunker adjacent to the bunker in which the pump (PCP) hydraulic top drive and flow switch were located. Steel beams, with plywood cover, at grade level protect the equipment and allow military tanks to drive over the oil field equipment during training exercises. No provision for ventilation, other than removing a few sheets of plywood, resulted in equipment overheating when snow accumulated on fully covered bunker. Similar overheating was noted during summer when the plywood was left in place to control blowing dirt.

The well’s horizontal portion is 155 mm diameter uncased 810 m in length at a depth of 955 m, between 0.75 and 1.25 metres below the over-burden in a 14.2 m thick glauconite, 25% porosity, 550 mD, bottom water drive reservoir. Heater location, near the heel and near the top of the reservoir, is not ideal for heating but it is typical of wells in the block. It was scheduled for a workover and was considered suitable for an evaluation of the MxL heater system. Accurate base line production figures were not available as the well produced into a group line and the turbine meters would not maintain calibration. During the latter part of operation a test trailer was used to measure fluid production.
Viscosity values from 11,000 to 16,000 cP at 30 °C were reported. The produced fluid consisted of a foamy water/oil emulsion with free water for a water cut figure in the mid 80% range.

3. Installation
Weather cold and windy, military advisories of limited access time were a concern throughout the installation. Connecting wires at joints in the cold and windy conditions added about six hours to the installation time combined with a damaged instrument cable, requiring a replacement from Calgary, runs the installation procedure into the second day.

At 1040 m into the hole an obstacle is encountered such that the string weight drops from 12 dN to zero and ramming is commenced resulting in slow progress. We attempt to obtain a load of hot water but the military threat of having to clear the site dictates that we use water from a site tank which is at 3 °C. The well is loaded with 4 Cubic M and with continued ramming we cease at 3 joints short of our target. At final depth the static string weight, above the obstruction, at onset of lowering is 9dN and the upward dynamic weight is 20 dN at a total horizontal reach of 650 meters. A drag of 11 dN for 300 meters of horizontal and 350 meters of curvature indicated that without the obstruction the 9 dN available string weight may have allowed us to reach an additional ((300 +(350/2)) x9/11 = approximately 300) meters into the horizontal without snubbing and with hot water that likely could have been increased considerably.

On start-up we were unable to retrieve meaningful data from the downhole sensors. We suspect that the ramming action damaged the instrument interconnections although the inductor winding resistance and inductance was unaffected.

4. Operation
Start-up calibration was completed based on the inductor winding resistance as had been the practice for earlier systems. The downhole data signal envelopes were being transmitted, by the downhole circuit board, but the data was not readable so sensor spot temperatures and bottom hole pressure values were not available. The inductor winding resistance values give an average temperature over each section of the tool and have proven reliable in the past for operation of the closed loop controls and for the operating data log. Had the downhole sensors and instruments functioned they would have provided twelve spot temperatures and two Bottom Hole Pressures (BHP) readings which can be of considerable value in managing the well.

The graph “Oil, Water, Gas and Temperature vs. Power Consumption from Dec. 2001 to Oct 2005” shows power (KVA), oil in bbl/d, % water cut, Gas oil ratio and temperatures for heater sections A, B and C from start-up in the fall of 2001 to September of 2004. There was an interruption in operation during April and May of 2002 due to flooding of the Motor Control Bunker, then during December the power was turned off to establish a base line for the flow meter. In early February 2004 the bunker overheated damaging the control transformer and because of limited site access, due to military training, it could not be replaced until April 18th, 2004. We had increased the output power to 60 KVA in January and since ventilation in the bunker is accomplished by removing plywood covers it is likely that they were left in place to prevent snow from filling the bunker. The PCU log showed a bunker temperature of 55 °C before the system stopped so when the transformer was replaced we added a 115 Volt outlet and thermostatic switch so that the operator could install a powered ventilation fan to ensure that the bunker would not overheat. At that time the system was given a thorough check and the SCR modules were replaced as a precautionary measure.
The MxL system is rated for 100 KVA but most of the time the system was operated between 30 and 50KVA because of limited power supply capability from the MCC bunker. During the summer of 2004 there were several opportunities to increase the MxL output power to approximately 70 KVA which raised the average wellbore temperature from 60 to 80 °C. The bunker ventilation fan had not been installed and in August of 2004 the bunker temperatures climbed above 55 °C on several occasions and the system shut down. Activities were suspended pending the disposition of production properties on the Suffield Block. Several unsuccessful attempts were made to interest the new owners in continuing the evaluation.

5. Observations
Accurate production information could not be obtained until the portable test trailer was made operational in January of 2003. Prior to that the turbine meter feeding into group lines was calibrated several times but in heavy oil their operation is quite erratic when handling oil and water slugs. In a similar manner wellhead samples drawn from a valve at the wellhead are not representative of the daily production. Therefore an accurate baseline of production before the heater was installed, and for the first fifteen months, is not available and as such the production figures prior to 2003, as given in the graph, should be considered as approximations.

With only 20% of the horizontal heated, near the heel, the fluid from beyond the tool combined with the inflow at inductor “C” (furthest from the heel) caused a mixed temperature about 10 °C cooler than “A” while “B” generally was only a few degrees cooler than “A”. During May 2003 reservoir temperatures averaged around 50 to 600 °C for power input of 15 KVA per phase which is 45% of system capacity. About the middle of May, 2004 we were able to increase power to 24 KVA per phase (70% of capacity) which increased inductor section A to 82 °C, B to 90 °C and section C to 68 °C. We expect that at 100% capacity temperature would have exceeded 100 °C.
MxL systems have shown a fifty to two hundred percent production increase (full zone is heated) and similar results might be expected, in the heated section, which should result in a 20 to 40% increase. We are encouraged by the results especially in view of the limited power and mixed flow which resulted in lower than optimum temperatures. The tool position, in close proximity to the overburden, is also a detrimental factor with respect to production but it is much harder to quantify. The completion arrangement showing location of the tool is given in “HORIZONTAL SUFFIELD BLOCK”.

The five fold increase in GOR following cessation of heating is interesting and leads to the question of gas migration to the upper part of the reservoir as a result of several years of increased reservoir temperature in the vicinity of the wellbore. Since the tool is within a metre of the cap rock the gas could readily cone back to the wellbore once heating ceased, oil cooled and the viscosity increased.

It would appear that application of the MxL Induction Heater allowed production to be sustained for a considerably longer time than adjacent wells that were not heated. Since no production base line is available prior to 2003 an assessment of production increase is not possible.

6. Third Party Comments
A major service company in evaluating our MxL technology made the following comments with respect to this installation:

• “ Oil rate of the heated well is significantly higher than most offsets and the watercut is definitely better than provided offsets.”
• “Near constant watercut is atypical of an aquifer fed water displacement. Water breakthrough has probably occurred at one place in the completed section, typical of this and other offset wells. The difference is this well’s deliverability is not adversely affected by the water breakthrough. The mobility enhancement afforded by heating probably supports the oil inflow characteristics and the near constant fluid rate mitigates water influx due to coning”

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